@article{ho_blackburn_goshe_williamson_2021, title={Identification of multiple proteins whose interaction with mannitol dehydrogenase is induced by salicylic acid: Implications for unconventional secretion}, ISSN={["1615-9861"]}, DOI={10.1002/pmic.202100091}, abstractNote={Abstract}, journal={PROTEOMICS}, author={Ho, Tricia C. and Blackburn, R. Kevin and Goshe, Michael B. and Williamson, John D.}, year={2021}, month={Sep} }
 @article{bhattarai_louws_williamson_panthee_2017, title={Resistance to Xanthomonas perforans
 race T4 causing bacterial spot in tomato breeding lines}, volume={66}, ISSN={0032-0862}, url={http://dx.doi.org/10.1111/ppa.12656}, DOI={10.1111/ppa.12656}, abstractNote={Tomato (Solanum lycopersicum) is the second most important vegetable crop in the world. Bacterial spot (BS) of tomato, caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans and X. gardneri, results in severe loss in yield and quality due to defoliation and formation of lesions on fruits, respectively. Currently management practices do not offer effective control under conditions of high disease pressure. Thus, developing BS resistance is a critical priority for tomato growers in order to minimize crop losses. Sixty‐three advanced tomato breeding lines, heirlooms and wild tomato lines with diverse genetic backgrounds were screened under greenhouse and field conditions for BS resistance using X. perforans race T4, which was found to be a prevalent race in North Carolina. Race T4 isolate 9 was used to inoculate the plants by spraying, and disease severity was measured using the Horsfall–Barratt scale. Tomato lines 74L‐1W(2008), NC2CELBR, 081‐12‐1X‐gsms, NC22L‐1 (2008) and 52LB‐1 showed resistance to BS in the field and/or greenhouse trials. These lines were derived from S. pimpinellifolium L3707. Screening L3707 followed by development of a mapping population and mapping resistance genes might be useful for breeding resistance against BS in future breeding programmes.}, number={7}, journal={Plant Pathology}, publisher={Wiley}, author={Bhattarai, K. and Louws, F. J. and Williamson, J. D. and Panthee, D. R.}, year={2017}, month={Jan}, pages={1103–1109} }
 @article{bhattarai_louws_williamson_panthee_2016, title={Differential response of tomato genotypes to Xanthomonas-specific pathogen-associated molecular patterns and correlation with bacterial spot (Xanthomonas perforans) resistance}, volume={3}, DOI={10.1038/hortres.2016.35}, abstractNote={Plants depend on innate immune responses to retard the initial spread of pathogens entering through stomata, hydathodes or injuries. These responses are triggered by conserved patterns in pathogen-encoded molecules known as pathogen-associated molecular patterns (PAMPs). Production of reactive oxygen species (ROS) is one of the first responses, and the resulting ‘oxidative burst’ is considered to be a first line of defense. In this study, we conducted association analyses between ROS production and bacterial spot (BS; Xanthomonas spp.) resistance in 63 genotypes of tomato (Solanum lycopersicum L.). A luminol-based assay was performed on leaf tissues that had been treated with a flagellin 22 (flg22), flagellin 28 and a Xanthomonas-specific flg22 (flg22-Xac) peptide, to measure PAMP-induced ROS production in each genotype. These genotypes were also assessed for BS disease response by inoculation with Xanthomonas perforans, race T4. Although there was no consistent relationship between peptides used and host response to the BS, there was a significant negative correlation (r=−0.25, P<0.05) between foliar disease severity and ROS production, when flg22-Xac was used. This response could potentially be used to identify the Xanthomonas-specific PRR allele in tomato, and eventually PAMP-triggered immunity loci could be mapped in a segregating population. This has potential significance in tomato improvement.}, journal={Horticulture Research}, author={Bhattarai, K. and Louws, F. J. and Williamson, J. D. and Panthee, Dilip}, year={2016} }
 @misc{patel_williamson_2016, title={Mannitol in Plants, Fungi, and Plant-Fungal Interactions}, volume={21}, ISSN={["1878-4372"]}, DOI={10.1016/j.tplants.2016.01.006}, abstractNote={Although the presence of mannitol in organisms as diverse as plants and fungi clearly suggests that this compound has important roles, our understanding of fungal mannitol metabolism and its interaction with mannitol metabolism in plants is far from complete. Despite recent inroads into understanding the importance of mannitol and its metabolic roles in salt, osmotic, and oxidative stress tolerance in plants and fungi, our current understanding of exactly how mannitol protects against reactive oxygen is also still incomplete. In this opinion, we propose a new model of the interface between mannitol metabolism in plants and fungi and how it impacts plant-pathogen interactions.}, number={6}, journal={TRENDS IN PLANT SCIENCE}, author={Patel, Takshay K. and Williamson, John D.}, year={2016}, month={Jun}, pages={486–497} }
 @article{la hovary_danehower_ma_reberg-horton_williamson_baerson_burton_2016, title={Phytotoxicity and Benzoxazinone Concentration in Field Grown Cereal Rye (Secale cereale L.)}, volume={2016}, ISSN={["1687-8167"]}, url={https://www.hindawi.com/journals/ija/2016/6463826/}, DOI={10.1155/2016/6463826}, abstractNote={Winter rye (Secale cerealeL.) is used as a cover crop because of the weed suppression potential of its mulch. To gain insight into the more effective use of rye as a cover crop we assessed changes in benzoxazinone (BX) levels in rye shoot tissue over the growing season. Four rye varieties were planted in the fall and samples harvested at intervals the following spring. Two different measures of phytotoxic compound content were taken. Seed germination bioassays were used as an estimate of total phytotoxic potential. Dilutions of shoot extracts were tested using two indicator species to compare the relative toxicity of tissue. In addition, BX (DIBOA, DIBOA-glycoside, and BOA) levels were directly determined using gas chromatography. Results showed that rye tissue harvested in March was the most toxic to indicator species, with toxicity decreasing thereafter. Likewise the BX concentration in rye shoot tissue increased early in the season and then decreased over time. Thus, phytotoxicity measured by bioassay and BX levels measured by GC have a similar but not identical temporal profile. The observed decrease in phytotoxic potential and plant BX levels in rye later in the season appears to correlate with the transition from vegetative to reproductive growth.}, journal={International Journal of Agronomy}, author={La Hovary, C. and Danehower, D. A. and Ma, G. and Reberg-Horton, C. and Williamson, J. D. and Baerson, S. R. and Burton, J. D.}, year={2016} }
 @article{williamson_desai_krasnyanski_ding_guo_nguyen_olson_dole_allen_2013, title={Overexpression of mannitol dehydrogenase in zonal geranium confers increased resistance to the mannitol secreting fungal pathogen Botrytis cinerea}, volume={115}, DOI={10.1007/s11240-013-0368-1}, number={3}, journal={Plant Cell, Tissue and Organ Culture}, author={Williamson, J. D. and Desai, A. and Krasnyanski, S. F. and Ding, F. and Guo, W. W. and Nguyen, T. T. and Olson, H. A. and Dole, J. M. and Allen, G. C.}, year={2013}, pages={367–375} }
 @article{blackburn_cheng_williamson_goshe_2010, title={Data-independent liquid chromatography/mass spectrometry (LC/MSE) detection and quantification of the secreted Apium graveolens pathogen defense protein mannitol dehydrogenase}, volume={24}, DOI={10.1002/rcm.4476}, abstractNote={Abstract}, number={7}, journal={Rapid Communications in Mass Spectrometry}, author={Blackburn, K. and Cheng, F. Y. and Williamson, J. D. and Goshe, M. B.}, year={2010}, pages={1009–1016} }
 @article{cheng_blackburn_lin_goshe_williamson_2009, title={Absolute Protein Quantification by LC/MSE for Global Analysis of Salicylic Acid-induced Plant Protein Secretion Responses}, volume={8}, ISSN={["1535-3907"]}, DOI={10.1021/pr800649s}, abstractNote={The plant cell wall is a dynamic cellular compartment consisting of a complex matrix of components that can change dramatically in response to environmental stresses. During pathogen attack, for instance, a wide spectrum of proteins that participate in various sequential processes involved in plant defense is secreted into the cell wall. In this study, a mass spectrometry, data-independent acquisition approach known as LC/MS (E) was used to assess temporal changes in the cell wall proteome in response to different levels of an endogenous inducer of plant disease defense responses, salicylic acid (SA). LC/MS (E) was used as a label-free method that enabled simultaneous protein identification and absolute femtomole quantification of each protein secreted into the extracellular matrix. A total of 74 secreted proteins were identified, 63 of which showed increased specific secretion in response to SA. A majority of this induced secretion occurred within 2 h of treatment, indicating that many proteins are involved in the early stages of plant defenses. We also identified a number of apparently nonclassically secreted proteins, suggesting that, as in many nonplant systems, Golgi/ER-independent mechanisms exist for plant protein secretion. These results provide new insight into plant apoplastic defense mechanisms and demonstrate that LC/MS (E) is a powerful tool for obtaining both relative and absolute proteome-scale quantification that can be applied to complex, time- and dose-dependent experimental designs.}, number={1}, journal={JOURNAL OF PROTEOME RESEARCH}, author={Cheng, Fang-yi and Blackburn, Kevin and Lin, Yu-min and Goshe, Michael B. and Williamson, John D.}, year={2009}, month={Jan}, pages={82–93} }
 @article{cheng_zamski_guo_pharr_williamson_2009, title={Salicylic acid stimulates secretion of the normally symplastic enzyme mannitol dehydrogenase: a possible defense against mannitol-secreting fungal pathogens}, volume={230}, ISSN={["1432-2048"]}, DOI={10.1007/s00425-009-1006-3}, abstractNote={The sugar alcohol mannitol is an important carbohydrate with well-documented roles in both metabolism and osmoprotection in many plants and fungi. In addition to these traditionally recognized roles, mannitol is reported to be an antioxidant and as such may play a role in host-pathogen interactions. Current research suggests that pathogenic fungi can secrete mannitol into the apoplast to suppress reactive oxygen-mediated host defenses. Immunoelectron microscopy, immunoblot, and biochemical data reported here show that the normally symplastic plant enzyme, mannitol dehydrogenase (MTD), is secreted into the apoplast after treatment with the endogenous inducer of plant defense responses salicylic acid (SA). In contrast, a cytoplasmic marker protein, hexokinase, remained cytoplasmic after SA-treatment. Secreted MTD retained activity after export to the apoplast. Given that MTD converts mannitol to the sugar mannose, MTD secretion may be an important component of plant defense against mannitol-secreting fungal pathogens such as Alternaria. After SA treatment, MTD was not detected in the Golgi apparatus, and its SA-induced secretion was resistant to brefeldin A, an inhibitor of Golgi-mediated protein transport. Together with the absence of a known extracellular targeting sequence on the MTD protein, these data suggest that a plant's response to pathogen challenge may include secretion of selected defensive proteins by as yet uncharacterized, non-Golgi mechanisms.}, number={6}, journal={PLANTA}, author={Cheng, Fang-yi and Zamski, Eli and Guo, Wei-wen and Pharr, D. Mason and Williamson, John D.}, year={2009}, month={Nov}, pages={1093–1103} }
 @article{cheng_locke_williamson_2008, title={Polyols in plants and pathogens: An integration of transport and function}, volume={9}, journal={Current Topics in Plant Biology}, author={Cheng, F.-Y and Locke, E. and Williamson, J. D.}, year={2008}, pages={101–114} }
 @article{leatherwood_pharr_dean_williamson_2007, title={Carbohydrate content and root growth in seeds germinated under salt stress}, volume={132}, number={6}, journal={Journal of the American Society for Horticultural Science}, author={Leatherwood, W. R. and Pharr, D. M. and Dean, L. O. and Williamson, J. D.}, year={2007}, pages={876–882} }
 @article{reberg-horton_burton_danehower_ma_monks_murphy_ranells_williamson_creamer_2005, title={Changes over time in the allelochemical content of ten cultivars of rye (Secale cereale L.)}, volume={31}, ISSN={["1573-1561"]}, DOI={10.1007/s10886-005-0983-3}, abstractNote={Published studies focused on characterizing the allelopathy-based weed suppression by rye cover crop mulch have provided varying and inconsistent estimates of weed suppression. Studies were initiated to examine several factors that could influence the weed suppressiveness of rye: kill date, cultivar, and soil fertility. Ten cultivars of rye were planted with four rates of nitrogen fertilization, and tissue from each of these treatment combinations was harvested three times during the growing season. Concentrations of a known rye allelochemical DIBOA (2,4-dihydroxy-1,4-(2H)benzoxazine-3-one) were quantified from the harvested rye tissue using high performance liquid chromatography (HPLC). Phytotoxicity observed from aqueous extracts of the harvested rye tissue correlated with the levels of DIBOA recovered in harvested tissue. The amount of DIBOA in rye tissue varied depending on harvest date and rye cultivar, but was generally lower with all cultivars when rye was harvested later in the season. However, the late maturing variety 'Wheeler' retained greater concentrations of DIBOA in comparison to other rye cultivars when harvested later in the season. The decline in DIBOA concentrations as rye matures, and the fact that many rye cultivars mature at different rates may help explain why estimates of weed suppression from allelopathic agents in rye have varied so widely in the literature.}, number={1}, journal={JOURNAL OF CHEMICAL ECOLOGY}, publisher={Springer Nature}, author={Reberg-Horton, SC and Burton, JD and Danehower, DA and Ma, GY and Monks, DW and Murphy, JP and Ranells, NN and Williamson, JD and Creamer, NG}, year={2005}, month={Jan}, pages={179–193} }
 @article{barb_pharr_williamson_2003, title={A Nicotiana tabacum cell culture selected for accelerated growth on mannose has increased expression of phosphomannose isomerase}, volume={165}, ISSN={["0168-9452"]}, DOI={10.1016/S0168-9452(03)00250-4}, abstractNote={Phosphomannose isomerase (PMI), a key enzyme in mannose (Man) metabolism, is expressed at very low levels in many plant species. For example, measured PMI activity in Nicotiana tabacum (NT1) suspension cells is relatively low, resulting in slow metabolism of Man. Not surprisingly then, NT1 cultures were observed to grow six times faster on glucose (Glc) than on Man as sole carbon source. We report here the selection of a mutant NT1 cell line that grows four times faster on Man than the parental culture from which it was derived. This cell line had fivefold greater PMI activity than the parental culture, which likely contributes to the increased growth rate on Man. The selected line continued to express elevated PMI activity after transfer to Glc, suggesting a stable genetic change. However, the selected line grew more slowly than the wild type on Glc. This was likely due to a more than 50% reduction in hexokinase (HK) activity, an enzyme that is required for the phosphorylation and subsequent metabolism of Glc. Unlike HK, fructokinase activity was essentially unchanged in the mutant cell lines. However, activities of the carbohydrate metabolic enzymes phosphoglucose isomerase and 6-phosphogluconate dehydrogenase were also higher in mutant cells.}, number={3}, journal={PLANT SCIENCE}, author={Barb, AW and Pharr, DM and Williamson, JD}, year={2003}, month={Sep}, pages={639–648} }
 @article{jennings_daub_pharr_williamson_2002, title={Constitutive expression of a celery mannitol dehydrogenase in tobacco enhances resistance to the mannitol-secreting fungal pathogen Alternaria alternata}, volume={32}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313X.2001.01399.x}, abstractNote={Summary}, number={1}, journal={PLANT JOURNAL}, author={Jennings, DB and Daub, ME and Pharr, DM and Williamson, JD}, year={2002}, month={Oct}, pages={41–49} }
 @article{williamson_2002, title={Plant biotechnology: Past, present, and future}, volume={127}, ISSN={["0003-1062"]}, DOI={10.21273/jashs.127.4.462}, abstractNote={and nontranslated RNAs (Beachy, 1997; Fitchen and Beachy, 1993). The effectiveness and range of PDR vary widely, and present data are inadequate to establish the precise molecular mechanisms of resistance for most. Nonetheless, in addition to developing disease-resistant plant varieties for agriculture (e.g., Asgrow’s Freedom II squash), PDR has increased our understanding of viral pathogenesis and disease. These advances in understanding the fundamental principles underlying resistance and pathogenicity, in turn, will likely lead to second generation genes that confer increased levels of sustainable resistance.}, number={4}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE}, author={Williamson, JD}, year={2002}, month={Jul}, pages={462–466} }
 @article{williamson_jennings_guo_pharr_ehrenshaft_2002, title={Sugar alcohols, salt stress, and fungal resistance: Polyols - Multifunctional plant protection?}, volume={127}, number={4}, journal={Journal of the American Society for Horticultural Science}, author={Williamson, J. D. and Jennings, D. B. and Guo, W. W. and Pharr, D. M. and Ehrenshaft, M.}, year={2002}, pages={467–473} }
 @article{zamski_guo_yamamoto_pharr_williamson_2001, title={Analysis of celery (Apium graveolens) mannitol dehydrogenase (Mtd) promoter regulation in Arabidopsis suggests roles for MTD in key environmental and metabolic responses}, volume={47}, ISSN={["0167-4412"]}, DOI={10.1023/A:1012395121920}, abstractNote={Of the growing list of promising genes for plant improvement, some of the most versatile appear to be those involved in sugar alcohol metabolism. Mannitol, one of the best characterized sugar alcohols, is a significant photosynthetic product in many higher plants. The roles of mannitol as both a metabolite and an osmoprotectant in celery (Apium graveolens) are well documented. However, there is growing evidence that 'metabolites' can also have key roles in other environmental and developmental responses in plants. For instance, in addition to its other properties, mannitol is an antioxidant and may have significant roles in plant-pathogen interactions. The mannitol catabolic enzyme mannitol dehydrogenase (MTD) is a prime modulator of mannitol accumulation in plants. Because the complex regulation of MTD is central to the balanced integration of mannitol metabolism in celery, its study is crucial in clarifying the physiological role(s) of mannitol metabolism in environmental and metabolic responses. In this study we used transformed Arabidopsis to analyze the multiple environmental and metabolic responses of the Mtd promoter. Our data show that all previously described changes in Mtd RNA accumulation in celery cells mirrored changes in Mtd transcription in Arabidopsis. These include up-regulation by salicylic acid, hexokinase-mediated sugar down-regulation, and down-regulation by salt, osmotic stress and ABA. In contrast, the massive up-regulation of Mtd expression in the vascular tissues of salt-stressed Arabidopsis roots suggests a possible role for MTD in mannitol translocation and unloading and its interrelation with sugar metabolism.}, number={5}, journal={PLANT MOLECULAR BIOLOGY}, author={Zamski, E and Guo, WW and Yamamoto, YT and Pharr, DM and Williamson, JD}, year={2001}, pages={621–631} }
 @inbook{pharr_williamson_2000, title={Carbohydrates}, booktitle={Plant sciences: Vol. 1}, publisher={New York: Macmillan Reference USA}, author={Pharr, D. M. and Williamson, J. D.}, year={2000}, pages={120–122} }
 @article{yamamoto_prata_williamson_weddington_pharr_2000, title={Formation of a hexokinase complex is associated with changes in energy utilization in celery organs and cells}, volume={110}, ISSN={["0031-9317"]}, DOI={10.1034/j.1399-3054.2000.110104.x}, abstractNote={We previously presented evidence that the hexose‐regulated repression of the mannitol catabolic enzyme mannitol dehydrogenase (MTD) in celery (Apium graveolens L.) may be mediated by hexokinase (EC 2.7.1.1) (HK) [Prata et al. (1997) Plant Physiol 114: 307–314]. To see if differential regulation of HK forms might be involved in the sugar‐regulated repression of MTD we characterized two forms of HK with respect to their expression in various plant organs as well as in celery suspension cell cultures. We found that the vast majority of HK activity was membrane‐associated, whereas fructokinase (EC 2.7.1.4) was found largely in the soluble cell fraction. Gel filtration chromatography further revealed the differential expression of two molecular size classes of HK. One HK (HK‐L) chromatographed at 68 kDa, a typical size for a plant HK, while the second (HK‐H) chromatographed at 280 kDa. This unique 280 kDa HK was shown to be composed of a 50 kDa HK protein, possibly complexed with other, as yet unidentified, components. The HK‐L was present in all cells and organs analyzed, and thus may be a likely candidate for mediation of sugar repression. In contrast, the presence of the HK‐H complex was specific to certain organs and cells grown under certain conditions. Our analyses here showed no correlation between the presence of the HK‐H and MTD repression or derepression in celery cells. Instead, the HK‐H complex was present exclusively in rapidly growing organs and cells, but not in non‐growing celery storage tissues or in carbon‐depleted celery suspension‐cultured cells. Furthermore, the HK‐H complex was present when Glc in the growth media was replaced with 2‐deoxy Glc, a HK substrate that does not provide energy for growth and metabolism. These results imply that the HK‐H complex may have a potentially unique role in the metabolism of rapidly growing celery cells, in particular, in hexose phosphorylation. We also found that mitochondria prepared from Glc‐grown celery suspension‐cultured cells contained substantial HK activity, and that oxygen uptake of these mitochondria was stimulated by Glc. These results are consistent with the hypothesis that mitochondrial localization of celery HK may play a role in rapid recycling of adenylate.}, number={1}, journal={PHYSIOLOGIA PLANTARUM}, author={Yamamoto, YT and Prata, RTN and Williamson, JD and Weddington, M and Pharr, DM}, year={2000}, month={Sep}, pages={28–37} }
 @article{feusi_burton_williamson_pharr_1999, title={Galactosyl-sucrose metabolism and UDP-galactose pyrophosphorylase from Cucumis melo L-fruit}, volume={106}, DOI={10.1034/j.1399-3054.1999.106102.x}, abstractNote={In muskmelon (Cucumis melo L.), sink tissues receive stachyose, raffinose and sucrose through phloem translocation of carbohydrates that are formed as products of leaf photosynthesis. Melon fruits accumulate sucrose massively during the final stages of maturation. This sucrose is derived partially from the catabolism of raffinose saccharides. Rapid galactose metabolism is required, because liberation of free galactose is the first step in the metabolic utilization of the raffinose sugars. The current study demonstrates that the enzyme UDP‐glucose‐hexose‐1‐P uridylyltransferase (EC 2.7.7.12), the central enzyme in the classical Lelior pathway, is not the central enzyme in galactose metabolism in muskmelon fruit. Rather, a broad substrate specificity UDP‐galactose pyrophosphorylase (PPase) serves the same functional role. This enzyme accepts either UDP‐galactose or UDP‐glucose as a substrate and is different from a UDP‐glucose PPase with more strict substrate specificity for UDP‐glucose that is also present in melon tissue. UDP‐galactose PPase was purified 113‐fold from melon tissue and was shown to be a 54 kDa (size exclusion chromatography) to 68 kDa (SDS‐PAGE) protein that is enzymatically active as a monomer. We also present evidence that the enzyme likely accepts UDP‐galactose and UDP‐glucose at the same catalytic site. Polyclonal antibodies prepared against this protein reacted with numerous other antigens in melon extracts, apparently as a result of the presence of common antigenic epitopes.}, number={1}, journal={Physiologia Plantarum}, author={Feusi, M. E. S. and Burton, J. D. and Williamson, J. D. and Pharr, D. M.}, year={1999}, pages={9–16} }
 @article{pharr_prata_jennings_williamson_zamski_yamamoto_conkling_1999, title={Regulation of mannitol dehydrogenase: Relationship to plant growth and stress tolerance}, volume={34}, number={6}, journal={HortScience}, author={Pharr, D. M. and Prata, R. T. N. and Jennings, D. B. and Williamson, J. D. and Zamski, E. and Yamamoto, Y. T. and Conkling, M. A.}, year={1999}, pages={1027–1032} }
 @article{stoop_williamson_conkling_mackay_pharr_1998, title={Characterization of NAD-dependent mannitol dehydrogenase from celery as affected by ions, chelators, reducing agents and metabolites}, volume={131}, ISSN={["0168-9452"]}, DOI={10.1016/S0168-9452(97)00243-4}, abstractNote={NAD-dependent mannitol dehydrogenase (MTD) from celery (Apium graveolens L. var. dulce (Mill.) Pers.) provides the initial step by which mannitol is committed to central metabolism and plays a critical role in regulating mannitol concentration in the plant. The pH optimum for mannitol oxidation occurs at pH 9.5 whereas the optimum for mannose reduction occurs at pH 6.5. Michaelis–Menten kinetics were exhibited for mannitol and NAD with Km values of 64 and 0.14 mM, respectively at pH 9.5. The Km for mannose and NADH were 745 mM and 1.27 μM, respectively at pH 6.5. The high Km for mannose is consistent with a reaction in situ favoring mannitol oxidation rather than mannose reduction. The observed down-regulation of MTD in salt stressed celery is not due to a direct inhibition by NaCl or macronutrients. Inhibition by the chelator 1,10-phenanthroline suggests that zinc is required for MTD activity. Reducing agents DTT, DTE and β-mercaptoethanol inactivated MTD reversibly. At pH 7.0, ADP and to a lesser extend AMP and ATP were competitive inhibitors, with respect to NAD, having apparent Ki’s of 0.24, 0.64 and 1.10 mM, respectively.}, number={1}, journal={PLANT SCIENCE}, author={Stoop, JMH and Williamson, JD and Conkling, MA and MacKay, JJ and Pharr, DM}, year={1998}, month={Jan}, pages={43–51} }
 @article{williamson_guo_pharr_1998, title={Cloning and characterization of a genomic clone (Accession No. AF067082) encoding mannitol dehydrogenase, a salt, sugar and SA regulated gene from celery (Apium graveolens L.)(#PGR98-137)}, volume={118}, number={1}, journal={Plant Physiology}, author={Williamson, J. D. and Guo, W-W. and Pharr, D. M.}, year={1998}, pages={329} }
 @article{jennings_ehrenshaft_pharr_williamson_1998, title={Roles for mannitol and mannitol dehydrogenase in active oxygen-mediated plant defense}, volume={95}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.95.25.15129}, abstractNote={Reactive oxygen species (ROS) are both signal molecules and direct participants in plant defense against pathogens. Many fungi synthesize mannitol, a potent quencher of ROS, and there is growing evidence that at least some phytopathogenic fungi use mannitol to suppress ROS-mediated plant defenses. Here we show induction of mannitol production and secretion in the phytopathogenic fungusAlternaria alternatain the presence of host-plant extracts. Conversely, we show that the catabolic enzyme mannitol dehydrogenase is induced in a non-mannitol-producing plant in response to both fungal infection and specific inducers of plant defense responses. This provides a mechanism whereby the plant can counteract fungal suppression of ROS-mediated defenses by catabolizing mannitol of fungal origin.}, number={25}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Jennings, DB and Ehrenshaft, M and Pharr, DM and Williamson, JD}, year={1998}, month={Dec}, pages={15129–15133} }
 @article{yamamoto_zamski_williamson_conkling_pharr_1997, title={Subcellular localization of celery mannitol dehydrogenase - A cytosolic metabolic enzyme in nuclei}, volume={115}, ISSN={["0032-0889"]}, DOI={10.1104/pp.115.4.1397}, abstractNote={Abstract}, number={4}, journal={PLANT PHYSIOLOGY}, author={Yamamoto, YT and Zamski, E and Williamson, JD and Conkling, MA and Pharr, DM}, year={1997}, month={Dec}, pages={1397–1403} }
 @article{prata_williamson_conkling_pharr_1997, title={Sugar repression of mannitol dehydrogenase activity in celery cells}, volume={114}, ISSN={["0032-0889"]}, DOI={10.1104/pp.114.1.307}, abstractNote={Abstract}, number={1}, journal={PLANT PHYSIOLOGY}, author={Prata, RTN and Williamson, JD and Conkling, MA and Pharr, DM}, year={1997}, month={May}, pages={307–314} }
 @article{zamski_yamamoto_williamson_conkling_pharr_1996, title={Immunolocalization of mannitol dehydrogenase in celery plants and cells}, volume={112}, ISSN={["0032-0889"]}, DOI={10.1104/pp.112.3.931}, abstractNote={Abstract}, number={3}, journal={PLANT PHYSIOLOGY}, author={Zamski, E and Yamamoto, YT and Williamson, JD and Conkling, MA and Pharr, DM}, year={1996}, month={Nov}, pages={931–938} }
 @misc{stoop_williamson_pharr_1996, title={Mannitol metabolism in plants: A method for coping with stress}, volume={1}, ISSN={["1360-1385"]}, DOI={10.1016/s1360-1385(96)80048-3}, abstractNote={Mannitol, a six carbon sugar alcohol, has heretofore received little attention from plant scientists, despite its wide distribution in nature. However, recent findings concerning the biochemistry and physiology of higher plants indicate that species that metabolize mannitol have several advantages over those that exclusively translocate sugars. One advantage is increased tolerance to salt- and osmotic-stress as a result of mannitol's function as a ‘compatible solute’. Another advantage is a possible role in plant responses to pathogen attack — thus mannitol metabolism may play roles in plant responses to both biotic and abiotic stresses.}, number={5}, journal={TRENDS IN PLANT SCIENCE}, author={Stoop, JMH and Williamson, JD and Pharr, DM}, year={1996}, month={May}, pages={139–144} }
 @inbook{pharr_stoop_studer feusi_williamson_massel_conkling_1995, title={Mannitol catabolism in plant sink tissues}, booktitle={Carbon Partitioning and Source-Sink Interactions in Plants, Current Topics in Plant Physiology, Vol. 13 (Madore, MA and Lucas, WJ, eds.)}, publisher={American Society of Plant Physiologists, Rockville, MD}, author={Pharr, D.M. and Stoop, J.M.H. and Studer Feusi, M.E. and Williamson, J.D. and Massel, M.O. and Conkling, M.A.}, editor={Madore, MA and Lucas, WJEditors}, year={1995}, pages={180–194} }
 @article{stoop_willamson_conkling_pharr_1995, title={PURIFICATION OF NAD-DEPENDENT MANNITOL DEHYDROGENASE FROM CELERY SUSPENSION-CULTURES}, volume={108}, ISSN={["0032-0889"]}, DOI={10.1104/pp.108.3.1219}, abstractNote={Mannitol dehydrogenase, a mannitol:mannose 1-oxidoreductase, constitutes the first enzymatic step in the catabolism of mannitol in nonphotosynthetic tissues of celery (Apium graveolens L.). Endogenous regulation of the enzyme activity in response to environmental cues is critical in modulating tissue concentration of mannitol, which, importantly, contributes to stress tolerance of celery. The enzyme was purified to homogeneity from celery suspension cultures grown on D-mannitol as the carbon source. Mannitol dehydrogenase was purified 589-fold to a specific activity of 365 [mu]mol h-1 mg-1 protein with a 37% yield of enzyme activity present in the crude extract. A highly efficient and simple purification protocol was developed involving polyethylene glycol fractionation, diethylaminoethyl-anion-exchange chromatography, and NAD-agarose affinity chromatography using NAD gradient elution. Sodium dodecyl sulfate gel electrophoresis of the final preparation revealed a single 40-kD protein. The molecular mass of the native protein was determined to be approximately 43 kD, indicating that the enzyme is a monomer. Polyclonal antibodies raised against the enzyme inhibited enzymatic activity of purified mannitol dehydrogenase. Immunoblots of crude protein extracts from mannitol-grown celery cells and sink tissues of celery, celeriac, and parsley subjected to sodium dodecyl sulfate gel electrophoresis showed a single major immunoreactive 40-kD protein.}, number={3}, journal={PLANT PHYSIOLOGY}, author={STOOP, JMH and WILLAMSON, JD and CONKLING, MA and PHARR, DM}, year={1995}, month={Jul}, pages={1219–1225} }
 @article{williamson_stoop_massel_conkling_pharr_1995, title={SEQUENCE-ANALYSIS OF A MANNITOL DEHYDROGENASE CDNA FROM PLANTS REVEALS A FUNCTION FOR THE PATHOGENESIS-RELATED PROTEIN ELI3}, volume={92}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.92.16.7148}, abstractNote={Mannitol is the most abundant sugar alcohol in nature, occurring in bacteria, fungi, lichens, and many species of vascular plants. Celery (Apium graveolens L.), a plant that forms mannitol photosynthetically, has high photosynthetic rates thought to results from intrinsic differences in the biosynthesis of hexitols vs. sugars. Celery also exhibits high salt tolerance due to the function of mannitol as an osmoprotectant. A mannitol catabolic enzyme that oxidizes mannitol to mannose (mannitol dehydrogenase, MTD) has been identified. In celery plants, MTD activity and tissue mannitol concentration are inversely related. MTD provides the initial step by which translocated mannitol is committed to central metabolism and, by regulating mannitol pool size, is important in regulating salt tolerance at the cellular level. We have now isolated, sequenced, and characterized a Mtd cDNA from celery. Analyses showed that Mtd RNA was more abundant in cells grown on mannitol and less abundant in salt-stressed cells. A protein database search revealed that the previously described ELI3 pathogenesis-related proteins from parsley and Arabidopsis are MTDs. Treatment of celery cells with salicylic acid resulted in increased MTD activity and RNA. Increased MTD activity results in an increased ability to utilize mannitol. Among other effects, this may provide an additional source of carbon and energy for response to pathogen attack. These responses of the primary enzyme controlling mannitol pool size reflect the importance of mannitol metabolism in plant responses to divergent types of environmental stress.}, number={16}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={WILLIAMSON, JD and STOOP, JMH and MASSEL, MO and CONKLING, MA and PHARR, DM}, year={1995}, month={Aug}, pages={7148–7152} }
 @article{pharr_stoop_williamson_feusi_massel_conkling_1995, title={The dual role of mannitol as osmoprotectant and photoassimilate in celery}, volume={30}, number={6}, journal={HortScience}, author={Pharr, D. M. and Stoop, J. M. H. and Williamson, J. D. and Feusi, M. E. S. and Massel, M. O. and Conkling, M. A.}, year={1995}, pages={1182–1188} }
 @article{williamson_scandalios_1994, title={THE MAIZE (ZEA-MAYS L) CAT1 CATALASE PROMOTER DISPLAYS DIFFERENTIAL BINDING OF NUCLEAR PROTEINS ISOLATED FROM GERMINATED AND DEVELOPING EMBRYOS AND FROM EMBRYOS GROWN IN THE PRESENCE AND ABSENCE OF ABSCISIC-ACID}, volume={106}, ISSN={["1532-2548"]}, DOI={10.1104/pp.106.4.1373}, abstractNote={We previously demonstrated that amounts of Cat1 RNA in developing immature maize (Zea mays L.) embryos change in parallel with endogenous abscisic acid (ABA) content. In excised immature embryos, addition of ABA leads to a large increase in Cat1 RNA accumulation. The Cat1 transcript, however, also accumulates to high amounts in scutella of germinating embryos, where ABA content is low and decreasing. Here we show that application of ABA to germinated embryos no longer results in the up-regulation of the Cat1 transcript accumulation that is seen during embryogenesis. This suggests that factors other than ABA control Cat1 expression at this developmental stage. Using band-shift and southwestern analyses, we show that the change in sensitivity to ABA is paralleled by changes in nuclear proteins binding to a 28-bp region of the Cat1 promoter in vitro. One protein (CAT1BP-20) shows increased accumulation in the absence of ABA, suggesting that a repressor-mediated mechanism accounts for at least a portion of the ABA regulation of Cat1.}, number={4}, journal={PLANT PHYSIOLOGY}, author={WILLIAMSON, JD and SCANDALIOS, JG}, year={1994}, month={Dec}, pages={1373–1380} }
 @article{williamson_scandalios_1993, title={Plant antioxidant gene response to fungal pathogens}, volume={1}, DOI={10.1016/0966-842x(93)90140-m}, abstractNote={Antioxidant defense systems are a prominent element in plant responses to environmental stress. Activated oxygen species have themselves been implicated as both a part of the plant's defense against pathogen attack as well as the phytotoxic component of photosensitizing fungal toxins. Molecular analyses are just beginning to define how plant oxidant and antioxidant genes might integrate with other defense responses to provide effective protection against pathogen attack.}, number={6}, journal={Soil Science and Plant Nutrition}, author={Williamson, J. D. and Scandalios, J. G.}, year={1993}, pages={239–245} }
 @article{williamson_scandalios_1993, title={Response of the maize catalases and superoxide dismutases to cercosporin-containing fungal extracts: the pattern of catalase response in scutella is stage specific}, volume={88}, DOI={10.1034/j.1399-3054.1993.880122.x}, number={1}, journal={Physiologia Plantarum}, author={Williamson, J. D. and Scandalios, J. G.}, year={1993}, pages={159–166} }
 @article{williamson_scandalios_1992, title={DIFFERENTIAL RESPONSE OF MAIZE CATALASES TO ABSCISIC-ACID - VP1 TRANSCRIPTIONAL ACTIVATOR IS NOT REQUIRED FOR ABSCISIC ACID-REGULATED CAT1 EXPRESSION}, volume={89}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.89.18.8842}, abstractNote={In this paper we describe the distinctive responses of the maize catalases to the plant growth regulator abscisic acid (ABA). We analyzed RNA and enzyme accumulation in excised maize embryos and found that each catalase responded differently to exogenously applied ABA. Levels of Cat1 transcript and enzyme activity rapidly increased. In contrast, levels of Cat2 transcript and protein decreased, while Cat3 transcript levels were not affected. In developing kernels of the ABA-deficient/biosynthetic viviparous mutant vp5, lower levels of Cat1 RNA correlated with lower endogenous ABA levels when compared to measured levels in comparably aged wild-type siblings from the same ear. The maize vp1 mutant line is morphologically insensitive to normal endogenous levels of ABA. Analysis of the response of Cat1 to exogenously applied ABA in mutant and wild-type vp1 sibling embryos suggests that, unlike other ABA-responsive genes analyzed to date, the Vp1 gene product is not essential for the ABA-mediated regulation of Cat1. The significance of these responses to ABA in defining the roles of the various CATs in maize is discussed.}, number={18}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={WILLIAMSON, JD and SCANDALIOS, JG}, year={1992}, month={Sep}, pages={8842–8846} }
 @article{williamson_scandalios_1992, title={Differential response of maize catalase and superoxide dismutase to the photoactivated fungal toxin cercosporin}, volume={2}, DOI={10.1046/j.1365-313x.1992.t01-33-00999.x}, abstractNote={Summary}, number={3}, journal={Plant Journal}, author={Williamson, J. D. and Scandalios, J. G.}, year={1992}, pages={351–358} }
 @article{acevedo_williamson_scandalios_1991, title={Photoregulation of the Cat2 and Cat3 catalase genes in pigmented and pigment-deficient maize - The circadian regulation of Cat3 is superimposed on its quasi-constitutive expression in maize leaves}, volume={127}, number={3}, journal={Genetics}, author={Acevedo, A. and Williamson, J. D. and Scandalios, J. G.}, year={1991}, pages={601–607} }
 @article{williamson_hirschwyncott_larkins_gelvin_1989, title={DIFFERENTIAL ACCUMULATION OF A TRANSCRIPT DRIVEN BY THE CAMV S-35 PROMOTER IN TRANSGENIC TOBACCO}, volume={90}, ISSN={["0032-0889"]}, DOI={10.1104/pp.90.4.1570}, abstractNote={A transcriptional fusion composed of the CaMV 35S promoter, a 19 kD zein cDNA, and the 3' flanking regions from the 0' to 1' T(R) T-DNA genes was introduced into tobacco (Nicotiana tabacum) by Agrobacterium-mediated transformation. The accumulation of RNA generated from this transcriptional fusion varied both temporally and spatially in all tissues examined in greenhouse-grown tobacco plants, suggesting that the CaMV 35S promoter is not constitutive. Younger, actively dividing leaf, stem, root, and flower tissues contained higher steady state levels of zein RNA than did older, more quiescent tissues. Zein RNA levels greatly decreased during seed development and were undetectable in the mature seed. In addition, the two RNA termination or processing signals present in our construct were differentially utilized during seed development.}, number={4}, journal={PLANT PHYSIOLOGY}, author={WILLIAMSON, JD and HIRSCHWYNCOTT, ME and LARKINS, BA and GELVIN, SB}, year={1989}, month={Aug}, pages={1570–1576} }
 @inproceedings{wallace_ohtani_lending_lopes_williamson_shaw_gelvin_larkins_1989, title={Factors affecting physical and structural properties of maize protein bodies}, volume={129}, ISBN={0471567396}, booktitle={Plant gene transfers: Proceedings of a UCLA symposium held at Park City, Utah, April 1-7, 1989}, publisher={New York: A. R. Liss}, author={Wallace, J. C. and Ohtani, T. and Lending, C. R. and Lopes, M. and Williamson, J. D. and Shaw, K. L. and Gelvin, S. B. and Larkins, B. A.}, editor={Lamb, C. and Beachy, R.Editors}, year={1989}, pages={205–216} }
 @article{williamson_quatrano_1988, title={ABA-REGULATION OF 2 CLASSES OF EMBRYO-SPECIFIC SEQUENCES IN MATURE WHEAT EMBRYOS}, volume={86}, ISSN={["0032-0889"]}, DOI={10.1104/pp.86.1.208}, abstractNote={We have previously described the isolation and characterization of ABA-enhanced sequences from developing wheat embryos. Here we use in vivo RNA labeling and the inhibitors alpha-amanitin and cycloheximide to determine the level at which ABA acts to modulate these sequences in cultured mature embryos. Sequences fell into two classes: one, represented by the 7S globulin clone, p511, appears to be regulated at the level of transcription, while the other, represented by the early methionine-labeled polypeptide (E(m))-protein clone, p1015, has an additional posttranscriptional component. In mature embryos cultured in the absence of ABA, mRNA levels of p511 and p1015 declined rapidly until neither was detected at 3 days postimbibition. Levels of p511 increased in mature embryos cultured in the presence of ABA, but remained low in the presence of ABA + alpha-amanitin, suggesting p511 RNA is regulated at the level of transcription. Levels of p1015, in contrast, remained high not only in the presence of ABA, but also in the presence of ABA + alpha-amanitin or alpha-amanitin alone. This suggests p1015 regulation might be at the level of selective RNA stability. Cycloheximide had no detectable effect on ABA-mediated stabilization of p1015, suggesting that newly synthesized proteins are not involved. E(m)-protein synthesis rates closely paralleled E(m) RNA levels, suggesting E(m) expression is not controlled at the level of translation.}, number={1}, journal={PLANT PHYSIOLOGY}, author={WILLIAMSON, JD and QUATRANO, RS}, year={1988}, month={Jan}, pages={208–215} }
 @article{williamson_galili_larkins_gelvin_1988, title={THE SYNTHESIS OF A 19-KILODALTON ZEIN PROTEIN IN TRANSGENIC PETUNIA PLANTS}, volume={88}, ISSN={["0032-0889"]}, DOI={10.1104/pp.88.4.1002}, abstractNote={Transcriptional fusions composed of a 19 kilodalton zein cDNA, the 5' flanking region from a beta-phaseolin gene, and 3' flanking regions from either the phaseolin or a 15-kilodalton zein gene were introduced into Petunia by Agrobacterium-mediated transformation. The expression of both zein mRNA and protein in these transgenic plants was seed-specific and developmentally regulated. Both monocot (zein) and dicot (phaseolin) polyadenylation consensus sequences were recognized in Petunia. Analysis by immunoblotting showed that the M(r) of the zein protein corresponded to that of the mature protein, suggesting that recognition and cleavage of the signal sequence had occurred. While zein mRNA accumulated to approximately 1% of the total poly(A)(+) RNA in seeds of the transformed plants, zein protein was present at a much lower concentration than expected, at most being 0.005% of the total seed protein. These results suggest that the 19 kilodalton zein gene, in addition to lacking specific sequences required for efficient transcription in dicots, might also lack sequences required for the efficient synthesis, targeting, transport, or stabilization of the protein.}, number={4}, journal={PLANT PHYSIOLOGY}, author={WILLIAMSON, JD and GALILI, G and LARKINS, BA and GELVIN, SB}, year={1988}, month={Dec}, pages={1002–1007} }
 @article{williamson_quatrano_cuming_1985, title={EM POLYPEPTIDE AND ITS MESSENGER-RNA LEVELS ARE MODULATED BY ABSCISIC-ACID DURING EMBRYOGENESIS IN WHEAT}, volume={152}, ISSN={["0014-2956"]}, DOI={10.1111/j.1432-1033.1985.tb09224.x}, abstractNote={The effect of abscisic acid (ABA) on the expression of the 'early-methionine-labeled' (Em) polypeptide was examined in cultured, immature wheat (Triticum aestivum, L.) embryos and in developing embryos in planta. A complementary DNA (cDNA) library was constructed from poly(A)-rich RNA from immature embryos cultured in the presence of ABA. ABA-enhanced sequences were first identified by differential colony-blot hybridization, and then verified using RNA slot-blot analysis. Dot-blot hybridization showed that one clone, p1015, was homologous to the previously isolated Em cDNA, pWG432. Electrophoretic analysis of the hybrid-select translation product of p1015 confirmed its identity as an Em sequence. Comparison of the p1015 cDNA insert size and the Em message size, from northern blot analysis, showed that p1015 contained about 87% of the Em sequence. RNA slot-blot analysis and protein electrophoresis showed that Em message, but not Em protein, accumulated at a low, basal level in immature embryos in the absence of ABA. Neither Em message nor Em protein was seen in three-day germinated seedlings. Steady-state levels of Em message and protein increased in immature embryos in the presence of ABA, both in culture and in planta. Regulation appeared to be primarily at the level of transcription or specific message stability. Regulation may also involve specific protein stability, since synthesis of Em protein continued in immature embryos in the absence of ABA, but Em protein did not accumulate in detectable amounts. We conclude that ABA specifically modulates Em message and protein levels in immature embryos, but is probably not responsible for the embryogenic specificity of Em expression.}, number={2}, journal={EUROPEAN JOURNAL OF BIOCHEMISTRY}, author={WILLIAMSON, JD and QUATRANO, RS and CUMING, AC}, year={1985}, pages={501–507} }
 @inproceedings{quatrano_ballo_williamson_hamblin_m._1983, title={ABA controlled expression of embryo-specific genes during wheat grain development}, volume={12}, ISBN={0845126113}, booktitle={Plant molecular biology: Proceedings of the ARCO Solar-UCLA Symposium, held in Keystone, Colorado, April 16-22, 1983}, publisher={New York: A. R. Liss}, author={Quatrano, R. S. and Ballo, B. L. and Williamson, J. D. and Hamblin, M. T. and M., Mansfield.}, year={1983}, pages={343–353} }