@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{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{firon_shaked_peet_pharr_zamski_rosenfeld_althan_pressman_2006, title={Pollen grains of heat tolerant tomato cultivars retain higher carbohydrate concentration under heat stress conditions}, volume={109}, ISSN={["0304-4238"]}, DOI={10.1016/j.scienta.2006.03.007}, abstractNote={Exposure to high temperatures (heat stress) causes reduced yield in tomatoes (Lycopersicon esculentum), mainly by affecting male gametophyte development. Two experiments were conducted where several tomato cultivars were grown under heat stress, in growth chambers (day/night temperatures of 31/25 °C) or in greenhouses (day/night temperatures of 32/26 °C), or under control (day/night temperatures of 28/22 °C) conditions. In heat-sensitive cultivars, heat stress caused a reduction in the number of pollen grains, impaired their viability and germinability, caused reduced fruit set and markedly reduced the numbers of seeds per fruit. In the heat-tolerant cultivars, however, the number and quality of pollen grains, the number of fruits and the number of seeds per fruit were less affected by high temperatures. In all the heat-sensitive cultivars, the heat-stress conditions caused a marked reduction in starch concentration in the developing pollen grains at 3 days before anthesis, and a parallel decrease in the total soluble sugar concentration in the mature pollen, whereas in the four heat-tolerant cultivars tested, starch accumulation at 3 days before anthesis and soluble sugar concentration at anthesis were not affected by heat stress. These results indicate that the carbohydrate content of developing and mature tomato pollen grains may be an important factor in determining pollen quality, and suggest that heat-tolerant cultivars have a mechanism for maintaining the appropriate carbohydrate content under heat stress.}, number={3}, journal={SCIENTIA HORTICULTURAE}, author={Firon, N. and Shaked, R. and Peet, M. M. and Pharr, D. M. and Zamski, E. and Rosenfeld, K. and Althan, L. and Pressman, E.}, year={2006}, month={Jul}, pages={212–217} }
 @article{griffin_ranney_pharr_2004, title={Heat and drought influence photosynthesis, water relations, and soluble carbohydrates of two ecotypes of redbud (Cercis canadensis)}, volume={129}, number={4}, journal={Journal of the American Society for Horticultural Science}, author={Griffin, J. J. and Ranney, T. G. and Pharr, D. M.}, year={2004}, pages={497–502} }
 @article{griffin_ranney_pharr_2004, title={Photosynthesis, chlorophyll fluorescence, and carbohydrate content of Illicium taxa grown under varied irradiance}, volume={129}, number={1}, journal={Journal of the American Society for Horticultural Science}, author={Griffin, J. J. and Ranney, T. G. and Pharr, D. M.}, year={2004}, pages={46–53} }
 @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_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{pressman_peet_pharr_2002, title={The effect of heat stress on tomato pollen characteristics is associated with changes in carbohydrate concentration in the developing anthers}, volume={90}, ISSN={["0305-7364"]}, DOI={10.1093/aob/mcf240}, abstractNote={Continuous exposure of tomato 'Trust' to high temperatures (day/night temperatures of 32/26 degrees C) markedly reduced the number of pollen grains per flower and decreased viability. The effect of heat stress on pollen viability was associated with alterations in carbohydrate metabolism in various parts of the anther during its development. Under control, favourable temperature conditions (28/22 degrees C), starch accumulated in the pollen grains, where it reached a maximum value 3 d before anthesis; it then diminished towards anthesis. During anther development, the concentration of total soluble sugars gradually increased in the anther walls and in the pollen grains (but not in the locular fluid), reaching a maximum at anthesis. Continuous exposure of the plants to high temperatures (32/26 degrees C) prevented the transient increase in starch concentration and led to decreases in the concentrations of soluble sugars in the anther walls and the pollen grains. In the locular fluid, however, a higher soluble sugar concentration was detected under the high-temperature regime throughout anther development. These results suggest that a major effect of heat stress on pollen development is a decrease in starch concentration 3 d before anthesis, which results in a decreased sugar concentration in the mature pollen grains. These events possibly contribute to the decreased pollen viability in tomato.}, number={5}, journal={ANNALS OF BOTANY}, author={Pressman, E and Peet, MM and Pharr, DM}, year={2002}, month={Nov}, pages={631–636} }
 @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} }
 @misc{pharr_stoop_1993, title={Mannitol oxidoreductase isolated from vascular plants}, volume={5268288}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Pharr, D. M. and Stoop, J. M. H.}, year={1993} }
 @article{pharr_motomura_1989, title={Anaerobiosis and carbohydrate status of the embryonic axis of germinating cucumber seeds}, volume={24}, number={1}, journal={HortScience}, author={Pharr, D. M. and Motomura, Y.}, year={1989}, pages={120} }
 @article{pharr_hendrix_robbins_gross_sox_1987, title={ISOLATION OF GALACTINOL FROM LEAVES OF CUCUMIS-SATIVUS}, volume={50}, ISSN={["0168-9452"]}, DOI={10.1016/0168-9452(87)90026-4}, abstractNote={A simple procedure for the isolation of galactinol from leaves of Cucumimis sativus L. has been developed. The procedure yielded approx. 60% of the galactinol originally present in leaves with an apparent purity of 97%. Gas chromatographic and mass spectral analysis indicated that the compound was identical to galactinol isolated from sugar beet. The cucumber leaf galactinol was found to be suitable as a substrate for a galactosyl transferase enzyme which catalyses the formation of stachyose.}, number={1}, journal={PLANT SCIENCE}, author={PHARR, DM and HENDRIX, DL and ROBBINS, NS and GROSS, KC and SOX, HN}, year={1987}, pages={21–26} }
 @article{pharr_huber_sox_1985, title={LEAF CARBOHYDRATE STATUS AND ENZYMES OF TRANSLOCATE SYNTHESIS IN FRUITING AND VEGETATIVE PLANTS OF CUCUMIS-SATIVUS L}, volume={77}, ISSN={["0032-0889"]}, DOI={10.1104/pp.77.1.104}, abstractNote={Carbon partitioning in the leaves of Cucumis sativus L., a stachyose translocating plant, was influenced by the presence or absence of a single growing fruit on the plant. Fruit growth was very rapid with rates of fresh weight gain as high as 3.3 grams per hour. Fruit growth was highly competitive with vegetative growth as indicated by lower fresh weights of leaf blades, petioles, stem internodes and root systems on plants bearing a single growing fruit compared to plants not bearing a fruit. Carbon exchange rates, starch accumulation rates and carbon export rates were higher in leaves of plants bearing a fruit. Dry weight loss from leaves was higher at night from fruiting plants, and morning starch levels were consistently lower in leaves of fruiting than in leaves of vegetative plants indicating rapid starch mobilization at night from the leaves of fruiting plants. Galactinol, the galactosyl donor for stachyose biosynthesis, was present in the leaves of fruit-bearing plants at consistently lower concentration than in leaves of vegetative plants. Galactinol synthase, and sucrose phosphate synthase activities were not different on a per gram fresh weight basis in leaves from the two plant types; however, stachyose synthase activity was twice as high in leaves from fruiting plants. Thus, the lower galactinol pools may be associated with an activation of the terminal step in stachyose biosynthesis in leaves in response to the high sink demand of a growing cucumber fruit.}, number={1}, journal={PLANT PHYSIOLOGY}, author={PHARR, DM and HUBER, SC and SOX, HN}, year={1985}, pages={104–108} }
 @article{pharr_sox_1984, title={CHANGES IN CARBOHYDRATE AND ENZYME LEVELS DURING THE SINK TO SOURCE TRANSITION OF LEAVES OF CUCUMIS-SATIVUS L, A STACHYOSE TRANSLOCATOR}, volume={35}, ISSN={["0304-4211"]}, DOI={10.1016/0304-4211(84)90227-X}, abstractNote={The sink to source transition of expanding leaves of cucumber was studied by sampling leaves sequentially from the growing stem apex toward the base of the plant. Leaf fresh weight and photosynthetic rate increased in the progression to lower nodes. Sucrose and raffinose concentrations were higher in sink leaves than in source leaves. Galactinol and stachyose concentrations increased during leaf expansion. Both alkaline and acidic α-galactosidase activity declined during leaf expansion, whereas galactinol synthase activity increased abruptly in leaves beginning in the leaf at the fourth node below the apex. This increase in activity corresponded temporally to marked changes in the oligosaccharide composition of the leaves in favor of galactosyl-saccharides, particularly stachyose. Across all leaf positions, galactinol synthase correlated positively with galactosyl-oligosaccharide concentration (r = 0.90) and correlated negatively with sucrose concentration (r = −0.82). The ratio of stachyose to raffinose correlated positively with the ratio of galactinol synthase to α-galactosidase (r = 0.95). The results point to the importance of changes in enzyme levels per se as determinants of changes in soluble carbohydrate levels associated with acquisition of export capability during leaf expansion.}, number={3}, journal={PLANT SCIENCE LETTERS}, author={PHARR, DM and SOX, HN}, year={1984}, pages={187–193} }
 @misc{fleming_pharr_thompson_1982, title={Altered brining properties of produce by a method of pre-brining exposure of the fresh produce to oxygen or carbon dioxide}, volume={4,352,827}, number={1982 Oct. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Fleming, H. P. and Pharr, D. M. and Thompson, R. L.}, year={1982} }
 @article{pharr_sox_smart_lower_fleming_1977, title={Identification and distribution of soluble saccharides in pickling cucumber plants and their fate in fermentation}, volume={102}, number={4}, journal={Journal of the American Society for Horticultural Science}, author={Pharr, D. M. and Sox, H. N. and Smart, E. L. and Lower, R. L. and Fleming, H. P.}, year={1977}, pages={406} }