@article{carbajal_ma_zuleta_reynolds_arellano_tredway_milla-lewis_2021, title={Identification of sources of resistance to gray leaf spot in Stenotaphrum germplasm}, volume={61}, ISSN={["1435-0653"]}, url={https://doi.org/10.1002/csc2.20371}, DOI={10.1002/csc2.20371}, abstractNote={AbstractSt. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a popular warm‐season turfgrass in the southern United States. Gray leaf spot (GLS), caused by the fungal pathogen Pyricularia oryzae Cavara, is one of the major diseases in St. Augustinegrass. Although previous studies have reported polyploid lines with resistance to GLS, no comprehensive evaluations of sources of resistance have been performed in the genus. Such evaluations will enable breeders to identify resistant parents for cultivar development. In this study, 58 genotypes of St. Augustinegrass and two genotypes of pembagrass [Stenotaphrum dimidiatum (L.) Brongn.] were screened for resistance to three different P. oryzae sources of inoculum under controlled environmental conditions. The parameters evaluated were incubation period, number of leaves with lesions, mean lesion length, area under the disease progress curve (AUDPC), and area under the lesion expansion curve (AULEC). Significant differences among genotypes were identified. Polyploid genotypes PI 365031, PI 290888, PI 300129, PI 300130, and cultivar ‘FX‐10’ and diploid genotype PI 410353 consistently showed high levels of resistance across trials, inoculum sources, and parameters. The identification of resistance genes in diploid genotypes is of great importance for future St. Augustinegrass breeding efforts, as this germplasm pool can be more readily exploited because of the lack of reproductive barriers with most commercial cultivars and plant introductions.}, number={5}, journal={CROP SCIENCE}, publisher={Wiley}, author={Carbajal, Esdras M. and Ma, Bangya and Zuleta, M. Carolina and Reynolds, W. Casey and Arellano, Consuelo and Tredway, Lane P. and Milla-Lewis, Susana R.}, year={2021}, month={Sep}, pages={3069–3079} }
 @article{yu_mulkey_zuleta_arellano_ma_milla-lewis_2020, title={Quantitative Trait Loci Associated with Gray Leaf Spot Resistance in St. Augustinegrass}, volume={104}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-04-20-0905-RE}, abstractNote={ Gray leaf spot (GLS), caused by Magnaporthe grisea, is a major fungal disease of St. Augustinegrass (Stenotaphrum secundatum), causing widespread blighting of the foliage under warm, humid conditions. To identify quantitative trait loci (QTL) controlling GLS resistance, an F1 mapping population consisting of 153 hybrids was developed from crosses between cultivar Raleigh (susceptible parent) and plant introduction PI 410353 (resistant parent). Single-nucleotide polymorphism (SNP) markers generated from genotyping-by-sequencing constituted nine linkage groups for each parental linkage map. The Raleigh map consisted of 2,257 SNP markers and spanned 916.63 centimorgans (cM), while the PI 410353 map comprised 511 SNP markers and covered 804.27 cM. GLS resistance was evaluated under controlled environmental conditions with measurements of final disease incidence and lesion length. Additionally, two derived traits, area under the disease progress curve and area under the lesion expansion curve, were calculated for QTL analysis. Twenty QTL were identified as being associated with these GLS resistance traits, which explained 7.6 to 37.2% of the total phenotypic variation. Three potential GLS QTL “hotspots” were identified on two linkage groups: P2 (106.26 to 110.36 cM and 113.15 to 116.67 cM) and P5 (17.74 to 19.28 cM). The two major effect QTL glsp2.3 and glsp5.2 together reduced 20.2% of disease incidence in this study. Sequence analysis showed that two candidate genes encoding β-1,3-glucanases were found in the intervals of two QTL, which might function in GLS resistance response. These QTL and linked markers can be potentially used to assist the transfer of GLS resistance genes to elite St. Augustinegrass breeding lines. }, number={11}, journal={PLANT DISEASE}, author={Yu, Xingwang and Mulkey, Steve E. and Zuleta, Maria C. and Arellano, Consuelo and Ma, Bangya and Milla-Lewis, Susana R.}, year={2020}, month={Nov}, pages={2799–2806} }
 @article{yu_brown_graham_carbajal_zuleta_milla-lewis_2019, title={Detection of quantitative trait loci associated with drought tolerance in St. Augustinegrass}, volume={14}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0224620}, abstractNote={St. Augustinegrass (Stenotaphrum secundatum) is a warm-season grass species commonly utilized as turf in the southeastern US. Improvement in the drought tolerance of St. Augustinegrass has significant value within the turfgrass industry. Detecting quantitative trait loci (QTL) associated with drought tolerance will allow for advanced breeding strategies to identify St. Augustinegrass germplasm with improved performance for this trait. A multi-year and multi-environment study was performed to identify QTL in a ‘Raleigh’ x ‘Seville’ mapping population segregating for phenotypic traits associated with drought tolerance. Phenotypic data was collected from a field trial and a two-year greenhouse study, which included relative water content (RWC), chlorophyll content (CHC), leaf firing (LF), leaf wilting (LW), green cover (GC) and normalized difference vegetative index (NDVI). Significant phenotypic variance was observed and a total of 70 QTL were detected for all traits. A genomic region on linkage group R6 simultaneously harbored QTL for RWC, LF and LW in different experiments. In addition, overlapping QTL for GC, LF, LW and NDVI were found on linkage groups R1, R5, R7 and S2. Sequence alignment analysis revealed several drought response genes within these regions. The QTL identified in this study have potential to be used in the future to identify genes associated with drought tolerance and for use in marker-assisted breeding.}, number={10}, journal={PLOS ONE}, author={Yu, Xingwang and Brown, Jessica M. and Graham, Sydney E. and Carbajal, Esdras M. and Zuleta, Maria C. and Milla-Lewis, Susana R.}, year={2019}, month={Oct} }
 @article{kimball_isleib_reynolds_zuleta_milla-lewis_2016, title={Combining ability for winter survival and turf quality traits in st. augustinegrass}, volume={51}, number={7}, journal={HortScience}, author={Kimball, J. A. and Isleib, T. G. and Reynolds, W. C. and Zuleta, M. C. and Milla-Lewis, S. R.}, year={2016}, pages={810–815} }
 @article{patel_milla-lewis_zhang_templeton_reynolds_richardson_biswas_zuleta_dewey_qu_et al._2015, title={Overexpression of ubiquitin-like LpHUB1 gene confers drought tolerance in perennial ryegrass}, volume={13}, ISSN={["1467-7652"]}, DOI={10.1111/pbi.12291}, abstractNote={SummaryHUB1, also known as Ubl5, is a member of the subfamily of ubiquitin‐like post‐translational modifiers. HUB1 exerts its role by conjugating with protein targets. The function of this protein has not been studied in plants. A HUB1 gene, LpHUB1, was identified from serial analysis of gene expression data and cloned from perennial ryegrass. The expression of this gene was reported previously to be elevated in pastures during the summer and by drought stress in climate‐controlled growth chambers. Here, pasture‐type and turf‐type transgenic perennial ryegrass plants overexpressing LpHUB1 showed improved drought tolerance, as evidenced by improved turf quality, maintenance of turgor and increased growth. Additional analyses revealed that the transgenic plants generally displayed higher relative water content, leaf water potential, and chlorophyll content and increased photosynthetic rate when subjected to drought stress. These results suggest HUB1 may play an important role in the tolerance of perennial ryegrass to abiotic stresses.}, number={5}, journal={PLANT BIOTECHNOLOGY JOURNAL}, publisher={Wiley-Blackwell}, author={Patel, Minesh and Milla-Lewis, Susana and Zhang, Wanjun and Templeton, Kerry and Reynolds, William C. and Richardson, Kim and Biswas, Margaret and Zuleta, Maria C. and Dewey, Ralph E. and Qu, Rongda and et al.}, year={2015}, month={Jun}, pages={689–699} }
 @article{isleib_milla-lewis_pattee_copeland_zuleta_shew_hollowell_sanders_dean_hendrix_et al._2015, title={Registration of ‘Sugg’ peanut}, volume={9}, ISSN={["1940-3496"]}, DOI={10.3198/jpr2013.09.0059crc}, abstractNote={‘Sugg’ (Reg. No. CV-125, PI 666112) is a large-seeded virginia-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar with partial resistance to four diseases that occur commonly in the Virginia–Carolina production area: early leafspot caused by Cercospora arachidicola S. Hori, Cylindrocladium black rot caused by Cylindrocladium parasiticum Crous, Wingfield & Alfenas, Sclerotinia blight caused by Sclerotinia minor Jagger, and tomato spotted wilt caused by the Tomato spotted wilt tospovirus. Sugg was developed as part of a program of selection for multiple disease resistance funded by growers, seed dealers, shellers, and processors. Sugg was tested under the experimental designation N03091T and released by the North Carolina Agricultural Research Service (NCARS) in 2009. Sugg was tested by the NCARS, the Virginia Agricultural Experiment Station, and five other state agricultural experiment stations and the USDA–ARS units participating in the Uniform Peanut Performance Tests. Sugg has alternate branching pattern, intermediate runner growth habit, medium green foliage, and high contents of fancy pods and medium virginia-type seeds. It has seeds with pink testa averaging 957 mg seed−1, approximately 40% jumbo and 46% fancy pods, and extra-large kernel content of ∼47%. Sugg is named in honor of Norfleet “Fleet” Sugg and the late Joseph “Joe” Sugg, cousins who served consecutively as executive directors of the North Carolina Peanut Growers Association from 1966 through 1993.}, number={1}, journal={J. Plant Reg.}, publisher={American Society of Agronomy}, author={Isleib, T.G. and Milla-Lewis, S.R. and Pattee, H.E. and Copeland, S.C. and Zuleta, M.C. and Shew, B.B. and Hollowell, J.E. and Sanders, T.H. and Dean, L.O. and Hendrix, K.W. and et al.}, year={2015}, pages={44–52} }
 @article{chandi_milla-lewis_jordan_york_burton_zuleta_whitaker_culpepper_2013, title={Use of AFLP Markers to Assess Genetic Diversity in Palmer Amaranth (Amaranthus palmeri) Populations from North Carolina and Georgia}, volume={61}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-12-00053.1}, abstractNote={Glyphosate-resistant Palmer amaranth is a serious problem in southern cropping systems. Much phenotypic variation is observed in Palmer amaranth populations with respect to plant growth and development and susceptibility to herbicides. This may be related to levels of genetic diversity existing in populations. Knowledge of genetic diversity in populations of Palmer amaranth may be useful in understanding distribution and development of herbicide resistance. Research was conducted to assess genetic diversity among and within eight Palmer amaranth populations collected from North Carolina and Georgia using amplified fragment length polymorphism (AFLP) markers. Pair-wise genetic similarity (GS) values were found to be relatively low, averaging 0.34. The highest and the lowest GS between populations were 0.49 and 0.24, respectively, while the highest and the lowest GS within populations were 0.56 and 0.36, respectively. Cluster and principal coordinate (PCO) analyses grouped individuals mostly by population (localized geographic region) irrespective of response to glyphosate or gender of individuals. Analysis of molecular variance (AMOVA) results when populations were nested within states revealed significant variation among and within populations within states while variation among states was not significant. Variation among and within populations within state accounted for 19 and 77% of the total variation, respectively, while variation among states accounted for only 3% of the total variation. The within population contribution towards total variation was always higher than among states and among populations within states irrespective of response to glyphosate or gender of individuals. These results are significant in terms of efficacy of similar management approaches both in terms of chemical and biological control in different areas infested with Palmer amaranth.}, number={1}, journal={WEED SCIENCE}, publisher={Weed Science Society}, author={Chandi, Aman and Milla-Lewis, Susana R. and Jordan, David L. and York, Alan C. and Burton, James D. and Zuleta, M. Carolina and Whitaker, Jared R. and Culpepper, A. Stanley}, year={2013}, pages={136–145} }
 @article{kimball_zuleta_martin_kenworthy_chandra_milla-lewis_2012, title={Assessment of molecular variation within 'Raleigh' St. Augustinegrass using amplified fragment length polymorphism markers}, volume={47}, DOI={10.21273/hortsci.47.7.839}, abstractNote={St. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a popular turfgrass in the southern United States as a result of its superior shade tolerance and relatively low input requirements. However, it is the least cold-tolerant of commonly used warm-season turfgrass species. ‘Raleigh’, released in 1980, has superior cold tolerance and is adapted and widely used in U.S. Department of Agriculture hardiness zones 8 to 9. More than 25 years after its release, ‘Raleigh’ is still the industry’s standard in terms of cold tolerance. However, the original foundation and breeder stock fields of the cultivar have been lost, placing the integrity of the cultivar at risk. The objectives of this study were to investigate whether current ‘Raleigh’ production fields across the southern United States are true to the original source. In this study, 15 amplified fragment length polymorphism (AFLP) primer combinations were used to assess levels of genetic variability among three original stocks of ‘Raleigh’ and 46 samples obtained from sod farms and universities in six states. Genetic similarities among the original stocks were Sij = 1, whereas similarities between this group and all other samples ranged from 0.24 to 1.0. Results based on cluster analysis, principal coordinate analysis, and analysis of molecular variance (AMOVA) revealed separation between original stocks of ‘Raleigh’ and some commercial samples. Results from this study offer further evidence that molecular markers provide a useful and powerful technique for identity preservation of clonally propagated cultivars and the detection of genetic variants in sod production fields and turfgrass breeding programs.}, number={7}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Kimball, J. A. and Zuleta, M. C. and Martin, M. C. and Kenworthy, K. E. and Chandra, A. and Milla-Lewis, S. R.}, year={2012}, pages={839–844} }
 @article{milla-lewis_zuleta_van esbroeck_quesenberry_kenworthy_2013, title={Cytological and Molecular Characterization of Genetic Diversity in Stenotaphrum}, volume={53}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2012.04.0234}, abstractNote={St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a warm‐season turfgrass broadly distributed across the southern United States. Here, we investigated genetic diversity and ploidy levels in publicly available plant introductions and cultivars of St. Augustinegrass as an aid to more effective use of these materials in breeding programs. Ploidy assignment of genotypes was problematic in some cases because of a lack of agreement between flow cytometry–inferred ploidy level and chromosome counts indicating that DNA content of higher ploidy genotypes was not a simple multiple of the diploid genome. Cytological investigations indicated five different ploidy levels (diploid, triploid, aneuploid, tetraploid, and hexaploid) with chromosome numbers ranging from 2n = 2x = 18 to 2n = 6x = 54. Principal coordinate and cluster analyses separated genotypes into distinct groups that were mostly congruent with ploidy levels. Moreover, analysis of molecular variance results based on amplified fragment length polymorphism genotyping indicated that 46% of the total variation could be explained by differences between ploidy levels. A clear positive correlation was observed between ploidy level and number of scored bands, with polyploids showing an increased number of bands. Variation in chromosome number is an important source of genetic variation in S. secundatum, and knowledge of the genetic relationships among accessions of this species can be an important consideration for the proper utilization of this germplasm in applied cultivar development.}, number={1}, journal={CROP SCIENCE}, publisher={Crop Science Society of America}, author={Milla-Lewis, Susana R. and Zuleta, M. Carolina and Van Esbroeck, George A. and Quesenberry, Kenneth H. and Kenworthy, Kevin E.}, year={2013}, month={Jan}, pages={296–308} }
 @article{harris-shultz_milla-lewis_zuleta_schwartz_hanna_brady_2012, title={Development of SSR markers and the analysis of genetic diversity and ploidy level in a centipedegrass collection}, volume={52}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2011.03.0151}, abstractNote={ABSTRACTLittle is known about the genetic variability of centipedegrass [Eremochloa ophiuroides (Munro) Hack.] and few genetic tools have been available for this species. In this study, 69 unique Eremochloa sequences were generated by using a compound simple sequence repeat (SSR)‐based cloning method. Twenty‐nine of these clones contained an internal SSR and 30 specific primer pairs were developed that produced suitable amplification. The level of genetic diversity was assessed using 55 centipedegrass accessions and one Eremochloa zeylanica Hack. accession using primer pairs developed from the compound SSR‐based cloning technique. Twenty‐four polymorphic fragments could be scored and unweighted pair‐group method using arithmetic averages (UPGMA) cluster analysis showed that the Eremochloa accessions clustered into two groups: a large cluster of E. ophiuroides accessions and a group containing the single E. zeylanica accession. Principle coordinate analysis further divided the centipedegrass accessions into three groups. Ploidy analysis revealed all centipedegrass accessions were diploid while the single E. zeylanica accession was found to be a putative tetraploid. Furthermore, many of these markers can be used for other species belonging to the subfamily Panicoideae. The division of the centipedegrass accessions into groups and analysis of ploidy level provides information that will aid in the effective use of this germplasm in breeding programs.}, number={1}, journal={Crop Science}, publisher={Crop Science Society of America}, author={Harris-Shultz, K.R. and Milla-Lewis, S.R. and Zuleta, M.C. and Schwartz, B.M. and Hanna, W.W. and Brady, J.A.}, year={2012}, pages={360–370} }
 @article{milla-lewis_harris-shultz_zuleta_kimball_schwartz_hanna_2012, title={Use of sequence-related amplified polymorphism (SRAP) markers for comparing levels of genetic diversity in centipedegrass germplasm}, volume={59}, ISSN={["1573-5109"]}, DOI={10.1007/s10722-011-9780-8}, number={7}, journal={Genetic Resources and Crop Evaluation}, publisher={Springer Science \mathplus Business Media}, author={Milla-Lewis, S.R. and Harris-Shultz, K.R. and Zuleta, M.C. and Kimball, J.A. and Schwartz, B.M. and Hanna, W.W.}, year={2012}, pages={1517–1526} }
 @article{milla-lewis_zuleta_isleib_2010, title={Assessment of Genetic Diversity among U.S. Runner-Type Peanut Cultivars Using Simple Sequence Repeat Markers}, volume={50}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2010.04.0223}, abstractNote={The scientific community has long assumed that plant breeding activities decrease genetic diversity in crop species. To determine the influence of plant breeding on peanut, this study was designed to assess allelic diversity changes among peanut (Arachis hypogaea L.) cultivars of the runner market type using simple sequence repeat (SSR) markers. All runner‐type cultivars released to date were included with the exception of ten cultivars released in the 2000s. Thirty‐four SSR primer pairs amplified a total of 154 alleles. The results indicated that (i) at the gene level, allelic diversity has increased significantly through decades of breeding, (ii) at the population level, genetic diversity was at its lowest during the pre‐1980s time period and gradually increased in each subsequent decade, and (iii) most of the observed SSR variation occurred within, rather than among time periods. A principal coordinate analysis (PCO) clearly demonstrated increases in the variation present in each subsequent breeding decade, reaching its maximum in the 2000s. Therefore, it appears that runner‐type peanut breeders have been successful at developing improved peanut cultivars while increasing levels of diversity in the last three decades of breeding. In addition, genetic relationships among cultivars reported in this study might be of use for peanut breeders when selecting parents for establishment of breeding populations.}, number={6}, journal={CROP SCIENCE}, publisher={Crop Science Society of America}, author={Milla-Lewis, Susana R. and Zuleta, M. Carolina and Isleib, T. G.}, year={2010}, pages={2396–2405} }
 @article{isleib_milla-lewis_pattee_copeland_zuleta_shew_hollowell_sanders_dean_hendrix_et al._2010, title={Registration of ‘Bailey’ peanut}, volume={5}, ISSN={["1940-3496"]}, DOI={10.3198/jpr2009.12.0742crc}, abstractNote={‘Bailey’ (Reg. No. CV‐111, PI 659502) is a large‐seeded virginia‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) with partial resistance to five diseases that occur commonly in the Virginia‐Carolina production area: early leaf spot (caused by Cercospora arachidicola Hori), late leaf spot [caused by Cercosporidium personatum (Berk. & M.A. Curtis) Deighton], Cylindrocladium black rot [caused by Cylindrocladium parasiticum Crous, M.J. Wingf. & Alfenas], Sclerotinia blight (caused by Sclerotinia minor Jagger), and tomato spotted wilt (caused by Tomato spotted wilt tospovirus). It also has partial resistance to southern stem rot (caused by Sclerotium rolfsii Sacc.). Bailey was developed as part of a program of selection for multiple‐disease resistance funded by growers, seedsmen, shellers, and processors. Bailey was tested under the experimental designation N03081T and was released by the North Carolina Agricultural Research Service (NCARS) in 2008. Bailey was tested by the NCARS, the Virginia Agricultural Experimental Station, and five other state agricultural experiment stations and the USDA‐ARS units participating in the Uniform Peanut Performance Tests. Bailey has an alternate branching pattern, an intermediate runner growth habit, medium green foliage, and high contents of fancy pods and medium virginia‐type seeds. It has approximately 34% jumbo and 46% fancy pods, seeds with tan testas and an average weight of 823 mg seed−1, and an extra large kernel content of approximately 42%. Bailey is named in honor of the late Dr. Jack E. Bailey, formerly the peanut breeding project's collaborating plant pathologist.}, number={1}, journal={J. Plant Reg.}, publisher={American Society of Agronomy}, author={Isleib, T.G. and Milla-Lewis, S.R. and Pattee, H.E. and Copeland, S.C. and Zuleta, M.C. and Shew, B.B. and Hollowell, J.E. and Sanders, T.H. and Dean, L.O. and Hendrix, K.W. and et al.}, year={2010}, pages={27–39} }
 @article{milla-lewis_zuleta_isleib_2010, title={Simple sequence repeat allelic diversity in virginia-type peanut cultivars released from 1943 to 2006}, volume={50}, DOI={10.2135/cropsci2009.09.0501}, abstractNote={Studies on genetic diversity in Arachis spp. using microsatellite markers have included few or no commercial cultivars among the genotypes analyzed. The primary objective of this investigation was to evaluate the utility of simple sequence repeat (SSR) markers for detecting molecular polymorphism among elite virginia‐type peanut germplasm. Within that context, we had a secondary objective of assessing the impact of decades of plant breeding on allelic diversity levels among virginia‐type peanut cultivars. All U.S. virginia‐type cultivated varieties (except four) released between 1943 and 2006 were genotyped at 39 microsatellite loci. A total of 171 alleles were amplified. Allelic frequencies ranged from 0.02 to 0.97, with an average of 0.27. Although no significant difference was observed for the number of alleles present between the initial and the most recent time periods, our results indicate that levels of diversity present in virginia‐type peanuts have fluctuated significantly since the 1940s and peaked during the 1970s. Our study demonstrates that microsatellite markers may be useful for detecting molecular variation among peanut cultivars. Moreover, this is the first report of using microsatellite markers to describe genetic diversity in a collection of cultivated varieties of peanut.}, number={4}, journal={Crop Science}, publisher={Crop Science Society of America}, author={Milla-Lewis, S. R. and Zuleta, M. C. and Isleib, T. G.}, year={2010}, pages={1348–1356} }