2011 Annual Report
We have also fine-mapped a SLB resistance gene on chromosome 6 to a region of about a centiMorgan. We have now identified several plants with transposon insertions which appear to disrupt the function of this gene. Analysis of these plants should lead to identification of the underlying gene.
We have continued with a project to develop a robust gene silencing system in maize in collaboration with a scientist at Nobel Foundation, OK. We have identified several lines of maize which can be used for viral induced gene silencing. However the phenotype is transitory and further work will be required to produce a truly robust system.
In collaboration with scientists at Purdue University, we have identified several more loci that affect the strength of the maize defense response using the maize nested association mapping population. We have investigated the temperature dependent nature of a rust resistance gene and have shown that this gene is entirely non-functional above 30oC.
Using a set of near isogenic lines we developed, we have identified several genome regions that confer resistance to multiple leaf pathogens of maize. We identified several loci from teosinte, the wild progenitor of maize, which are associated with resistance to southern leaf blight and gray leaf spot. We have produced segregating populations in order to verify the effects of these loci.
Millions of deoxyribonucleic acid (DNA) variants were tested to identify 50 - 100 associated with the flowering response of maize to long daylengths. Several of these associated variants are in or adjacent to genes that have been shown to control daylength responses in other crops.
Superior backcross-derived lines combining resistance to Fusarium ear rot and hybrid yield potential were identified. 75 advanced lines from the USDA Germplasm Enhancement of Maize (GEM) project and the North Carolina State University maize inbred development programs were tested for resistance to Fusarium ear rot and fumonisin contamination resistance. 100 GEM lines were tested for resistance to SLB.
Eller, M.S., Payne, G.A., Holland, J.B. 2010. Selection for Reduced Fusarium Ear Rot and Fumonisin Content in Advanced Backcross Maize Lines and Their Topcross Hybrids. Crop Science. 50:2249-2260.
Kump, K., Bradbury, P., Buckler IV, E.S., Belcher, A., Oropeza-Rosas, M., Wisser, R., Zwonitzer, J., Kresovich, S., McMullen, M.D., Ware, D., Balint Kurti, P.J., Holland, J.B. 2011. Genome-wide association study of quantitative resistance to southern leaf blight in the maize nested association mapping population. Nature Genetics. 43:163-168.
Kump, K.L., Holland, J.B., Jung, M.T., Wolters, P., Balint Kurti, P.J. 2010. Joint Analysis of Near Isogenic and Recombinant Inbred Line Populations Yields Precise Positional Estimates for QTL. The Plant Genome. 3:142-153.
Wisser, R., Kolkman, J., Patzoldt, M., Holland, J.B., Jianming, Y., Krakowsky, M.D., Nelson, R., Balint Kurti, P.J. 2011. Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene. Proceedings of the National Academy of Sciences. 108:7339-7344.
Wisser, R., Balint Kurti, P.J., Holland, J.B. 2011. A novel genetic framework for studying response to artificial selection. Plant Genetic Resources. 9:281-283.
Coles, N., Zila, C., Holland, J.B. 2011. Functional Allelic Variation at Key Photoperiod Response QTL in Maize. Crop Science. 51:1036-1049.
Nageri, A., Coles, N., Holland, J.B., Balint Kurti, P.J. 2011. Mapping QTL controlling southern leaf blight resistance by combined analysis of three related recombinant inbred line populations. Crop Science. 51:1571-1579.
Jumbo, M., Weldekidan, T., Holland, J.B., Hawk, J. 2011. Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development Using GEM Breeding Crosses. Crop Science. 51:1534-1543.