Late-Season drought tolerance in maize and sorghum
The ability of a plant to postpone senescence under late-season drought is commonly defined as 'stay-green'. Stay-green is correlated with enhanced crop productivity, grain quality, and lodging resistance in many crops. Retention of green leaf tissue is known as visual stay-green, whereas functional stay-green is defined by maintenance of photosynthetically active tissue. The goal of our research is to characterize the expression and genetic architecture of stay-green in maize and sorghum. This knowledge will be applied to improving drought tolerance of these and other crops through marker-assisted selection and potentially transgenic approaches.
Maize exhibits substantial genetic variation for stay-green. Joint linkage mapping has been used to identify multiple QTL for stay-green across several linkage groups with sources of stay-green alleles coming from diverse genetic backgrounds. Comparisons between maize and sorghum for map positions of stay-green QTL indicate that two of the major loci occur in syntenous regions. Identification and integration of stay-green genes into commercial programs provides the opportunity to sustainably enhance the productivity of maize and sorghum in drought environments.
Heat tolerant maize for Asia
Climate change is forcing changes in agriculture and food production. Increasing temperatures are one of the prominent problems associated with climate change. Heat stress in maize can influence the overall health and production of the crop with yield losses realized through premature senescence of vegetative and reproductive structures. The Heat Tolerant Maize for Asia (HTMA) project is a Global Development Alliance to increase our understanding of heat stress tolerance in maize with partners including CIMMYT, Purdue University, and Pioneer Hi-Bred was well as partners in the National Agricultural Research Systems (NARS) and seed companies from South Asia through the support of USAID. The partners are collaborating in research to understand heat stress tolerance at the physiological and genetic level and to create superior maize hybrids that thrive under these conditions.
Developing a functional gene discovery platform for sorghum improvement
Tremendous gaps remain in our understanding of the valuable traits contained in sorghum genetic resources. Advances in genomics, targeted mutagenesis, reverse genetics and whole-genome DNA sequencing can enable efficient gene discovery and germplasm mining for crop improvement. With support of the BMGF, we are developing genetic and genomic resources that can be used to leverage the phenotypic variation in sorghum. By developing tools in the genome-sequenced variety BTx623 and elite germplasm adapted for Africa, this project accelerates the ability of sorghum researchers to translate knowledge into practical applications in sorghum improvement.
Using this resource, African breeding programs will identify candidate genes impacting traits of value to them, easily survey alleles of those genes in sequence-indexed collections of EMS mutants and diversity panels of local and globally important lines and landraces. The best alleles for improving their target trait can then be crossed into locally adapted breeding stocks. In addition, African laboratories and breeding programs will be trained in the informatics tools needed to use rapidly expanding and available genomics databases to enable more rapid and more effective sorghum breeding.
Modifying dhurrin metabolism in sorghum
Dhurrin accumulation in sorghum plant tissues negatively impacts forage quality for animal production. A genetic mutant of sorghum that does not accumulate dhurrin was reported by Blomstedt et al. (2012). This mutant was described as a P414L mutation in CYP79A1 but the mutant was reported to grow more slowly than wild-type plants. We have conducted forward genetic screens of a chemically mutagenized sorghum population and identified several new genetic variants that disrupt dhurrin metabolism. Whole genome resequencing experiments demonstrated that one of these variants harbored a C493Y mutation in CYP79A1 that disrupts dhurrin biosynthesis. Plants with this mutation do not exhibit a slow-growth phenotype. This mutation may provide a new genetic resource for eliminating dhurrin production in sorghum to improve feed, forage, and bioenergy feedstock value.
Use of seed treatment and acetolactate synthase herbicide tolerance traits for managing witchweed (Striga spp.) infestations in sorghum
Weed management is one of the most important considerations impacting sorghum production today. In Africa, witchweed (Striga spp.) infestations are a growing menace for cereal crop producers across the continent. One new and very promising Striga management technology involves use of herbicide tolerance traits for managing this weed. Low-dose imazapyr or metsulfuron seed coatings applied to herbicide tolerant varieties have been shown to be highly effective in controlling Striga infestation in field and greenhouse trials. Locally-adapted varieties that couple host-plant resistance to Striga with herbicide seed treatments are being developed to identify the combination of traits that maximizes the efficacy of control.
New stable-dwarf sorghum varieties
Sorghum plant height is a quantitative trait controlled by four major genes (Dw1:Dw2:Dw3:Dw4). Nearly all of the grain sorghum grown in the developed world is produced using semi-dwarf cultivars. These cultivars commonly are called "3-dwarf" sorghum since they utilize recessive dwarfing alleles at three of the four major dwarfing genes (dw1:Dw2:dw3:dw4). Karper (1932) was the first to note that the dw3 mutation produced a useful dwarf phenotype, but also noted that dw3 was unstable and frequently reverted to wild-type Dw3. These plants are tall and generally referred to as "height mutants". Farmers dislike height mutants because these off-types are unsightly in commercial grain production fields. Commercial seed producers do not like height mutants because of the effort and cost required to rogue these plants from seed production fields. These management efforts increase the "cost-of-goods" and, in some cases, seed lots must be destroyed if the frequency of off-types is too high. A novel dw3 allele (dw3-sd2) with a 6-bp deletion in the coding region of gene has been identified. This new allele is being incorporated into elite sorghum parent lines for deployment in commercial hybrids.
2007 – present Wickersham Chair of Excellence in Agricultural Research, Department of Agronomy, Purdue University
2007 – present Professor, Department of Agronomy, Purdue University
2006-2007 Professor, Department of Agronomy, Kansas State University
2001-2005 Associate Professor, Department of Agronomy, Kansas State University
1997-2001 Assistant Professor, Department of Agronomy, Kansas State University
1997 Post-Doctoral Fellow, Department of Agronomy, Purdue University
1991-1996 Research and Teaching Assistant, Purdue University
AGRY285: World Crop Adaptation and Distribution
AGRY550: Field Crops Breeding Techniques
AGRY611: Quantitative Genetics
Honors and Awards
Seeds for Success, Purdue University, 2009, 2013
Wickersham Chair of Excellence in Agricultural Research, Purdue University, 2007
Gamma Sigma Delta – Early Career Award, 2001
Student Travel Award, International Society of Plant Molecular Biology, 1996
Excellence in Biological Research Graduate Scholarship, Dow Elanco, 1995
Fellow, Gamma Sigma Delta – The Honor Society of Agriculture, 1994
McKnight Doctoral Fellowship, McKnight Foundation, 1994
Krothapalli K, Buescher EM, Li X, Brown E, Chapple C, Dilkes BP, Tuinstra MR. 2013. Dhurrinase2 is required for cyanide release from Sorghum bicolor. Genetics 195: 309–318.
Ciampitti IA, Murrell T, Camberato J, Tuinstra MR, Friedemann P, Vyn T. 2013. Physiological Dynamics of Maize Nitrogen Uptake and Partitioning in Response to Plant Density and N Stress Factors: II. Reproductive Phase. Crop Science 53: 2588-2602.
Ciampitti IA, Murrell T, Camberato J, Tuinstra MR, Friedemann P, Vyn T. 2013. Physiological processes governing nitrogen uptake dynamics of maize plant components in response to plant density and N stress factors: I. Vegetative phase. Crop Science 53: 2105-2119.
Kaufman RC, Herald TJ, Bean SR, Wilson JD, Tuinstra MR. 2013. Variability in tannin content, chemistry and activity in a diverse group of tannin containing sorghum cultivars. Journal of the Science of Food and Agriculture 93: 1233-1241.
Pontieri P, Mamone G, De Caro S, Tuinstra MR, Roemer E, Okot J, De Vita P, Ficco DBM, Alifano P, Pignone D, Massardo DR, Del Giudice L. 2013. Sorghum, a healthy and gluten-free food for celiac patients as demonstrated by genome, biochemical, and immunochemical analyses. Journal of Agricultural and Food Chemistry 61: 2565-2571.
Torres-Avila M, Davis ALE, Tuinstra MR, Unruh Snyder LJ. 2013. Student perceptions and performance of an online teaching tool: Introduction the concepts of plant breeding. NACTA Journal 57(1): 41-46.
Sukumaran S, Xiang W, Bean SR, Pedersen JF, Tuinstra MR, Tesso TT, Hamblin MT, Yu J. 2012. Association mapping for grain quality in a diverse Sorghum collection. Plant Genome 5: 126-135. doi: 10.3835/plantgenome2012.07.0016.
Barrero Farfan ID, Johal G, Tuinstra MR. 2012. A stable dw3 allele in sorghum and a molecular marker to facilitate selection. Crop Science 52: 2063-2069. doi:10.2135/cropsci2011.12.0631.
Pontieri P, De Vita P, Boffa A, Tuinstra MR, Bean S, Krishnamoorthy G, Miller C, Roemer E, Alifano P, Pignone D, Massardo D, Del Giudice L. 2012. Yield and morpho-agronomical evaluation of food-grade white sorghum hybrids grown in Southern Italy. Journal of Plant Interactions 7 (4): 341-347. DOI: 10.1080/17429145.2012.705340.
Wu Y, Xianran L, Xiang W, Zhu C, Lin Z, Wu Y, Li J, Pandravada S, Ridder DD, Bai G, Wang M, Trick H, Bean S, Tuinstra MR, Tesso T, Yu J. 2012. Presence of tannins in sorghum grains is conditioned by different natural alleles of Tan1. Proceedings of the National Academy of Sciences. 109: 10281–10286. doi: 10.1073/pnas.1201700109.
Lin Z, Li X, Wang ML, Bai G, Li J, Clemente TE, Trick HN, Tuinstra MR, Tesso TT, White F, Yu J. 2012. Parallel domestication of SHATTERING1 gene in crops. Nature Genetics 44: 720-724. doi:10.1038/ng.2281.
Kershner KS, Al-Khatib K, Krothapalli K, Tuinstra MR. 2012. Genetic resistance to acetyl-coenzyme A carboxylase-inhibiting herbicides in grain sorghum. Crop Science 52: 64-73.