1. Combining Genes for Pre-Harvest Sprout Resistance in White Wheat Kirsten Thomas and Herb Ohm #125 Introduction Pre-harvest sprouting (PHS) is a significant problem in white wheat in humid climates globally that leads to severely lowered grain quality and economic loss for producers. Pre-harvest sprouting occurs when the seed germinates before it is harvested. The most effective method for controlling pre-harvest sprouting is through the use of PHS resistant cultivars (cvs.). Resistance genes for the white wheat cultivars Leader, Cayuga, and RioBlanco have been identified and mapped. The objective of this research is to combine the PHS resistance of these three cultivars and determine if PHS resistance is augmented with the combination of the resistance factors. Methods The white wheat cvs. Leader, Cayuga, and RioBlanco have PHS resistance that have been mapped to different chromosomes. The PHS susceptible white wheat line Van98W- 170WS is included here as a negative control. The single crosses Leader x Cayuga (cross ‘A’) and RioBlanco x Cayuga (cross ‘B’) were made, and then F 1 plants from the two single crosses were crossed (cross ‘C’) to combine the respective PHS resistance factors of the three PHS resistance donor cultivars. The three PHS resistance donor parent cultivars and F 1 plants from cross C were screened with the respective markers from published sources (Table 1). Table 1. Published Markers Associated with PHS Resistance CultivarMarkersChromosome Leader barc170 4AL gwm397 gwm637 hbe03 RioBlancobarc123AS barc54 barc321 Cayugabarc552B wmc453 Table 2. Crosses Made to Combine PHS Resistance Factors F 1 Cross (single)Parentage Cross ALeader/Cayuga Cross BRioBlanco/Cayuga F 2 Cross (double)Parentage Cross C Leader/Cayuga// RioBlanco/Cayuga Results To date, the presence of the published markers (Table 1) in the parent cultivars has been confirmed. The following shows the gel images (Figures 2-3) of the parent cultivars and their respective markers (Table 3): Figure 2. Table 3. Location of Parent Cultivars with Respective Markers on the Gels Information for Figure 2: Gel 1Information for Figure 3: Gel 2 CultivarMarkerGel LaneCultivarMarkerGel Lane Controlbarc552Controlbarc542 Cayugabarc553RioBlancobarc543 Cayugabarc554RioBlancobarc544 Cayugabarc555RioBlancobarc545 Controlwmc4536RioBlancobarc546 Cayugawmc4537RioBlancobarc547 Cayugawmc4538RioBlancobarc548 Cayugawmc4539Controlbarc579 Controlgwm39710RioBlancobarc5710 Leadergwm39711RioBlancobarc5711 Leadergwm39712RioBlancobarc5712 Controlbarc17013RioBlancobarc5713 Leaderbarc17014RioBlancobarc5714 Controlhbe0315RioBlancobarc5715 Leaderhbe0316Controlbarc32116 Leaderhbe0317RioBlancobarc32117 Controlgwm63718RioBlancobarc32118 Leadergwm63719RioBlancobarc32119 Leadergwm63720RioBlancobarc32120 Controlbarc1221RioBlancobarc32121 RioBlancobarc1222RioBlancobarc32122 RioBlancobarc1223Controlwmc45323 RioBlancobarc1224Cayugawmc45324 RioBlancobarc1225Cayugawmc45325 RioBlancobarc1226Cayugawmc45326 Figure 3. Conclusion The expected outcome of this research is the identification of a true-breeding white wheat line that has all of the PHS resistance QTLs from all three parents. It is hypothesized that the PHS resistance of lines with multiple resistance QTLs will have more effective PHS resistance (augmented resistance) than the parent cultivars. Research Plans: Current Grow parent cvs. and selected F 2 plants from cross ‘C’ in a greenhouse, August-November 2011 Screen F 2 plants with markers to identify plants that have the PHS resistance factors of all three parents in homozygous state. Figure 1. A continuum of pre- harvest sprouting in wheat. The most resistant plants are shown at right, while the most susceptible are shown at left. Photo courtesy of the University of Minnesota. References 1. Li, C., P. Ni, M. Francki, A. Hunter, Y. Zhang, D. Schibeci, H. Li, A. Tarr, J. Wang, M. Cakir, J. Yu, M. Bellgard, R. Lance, R. Appels. 2004. Genes controlling seed dormancy and pre-harvest sprouting in a rice-wheat-barley comparison. 4:84-93. 2. Lui, S., S. Cai, R. Graybosch, C. Chen, and G. Bai. 2008. Quantitative trait loci resistance to pre- harvest sprouting in US hard white winter wheat Rio Blanco. Theoretical and Applied Genetics. 117:691-699. 3. Munkvold, J.D., J. Tanaka, D. Benscher, and M.E. Sorrels. 2009. Mapping quantitative trait loci for preharvest sprouting resistance in white wheat. Theoretical and Applied Genetics. 119:1223-1235. 4. Torada, A., S. Ikeguchi, and M. Koike. 2005. Mapping and validation of PCR-based markers associated with a major QTL for seed dormancy in wheat. Euphytica. 143:251-255. Future Dec2011-Jan2012: vernalize F 3 progeny families from selected F 2 plants; also vernalize 15 seedlings of Leader, Rio Blanco and Cayuga; and white and red wheat checks, including the PHS susceptible white wheat lines, Van98W-170WS (early maturity) and an additional line to be decided (midseason maturity), and the winter red wheat cvs. Clark (early maturity) and INW1131 (midseason maturity). Late Feb2012: transplant F 3 families and cvs./lines to a field nursery; screen several F 3 plants of each family with markers to verify presence/homozygosity of the PHS resistance factors of all three parents; record data on preharvest sprouting severity of the grain samples. Aug2012 – Nov2012: Determine PHS of F 4 lines, donor parents, and white and red checks under controlled misting system in a greenhouse.