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GrainGenes Reference Report: PBR-123-405

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Reference	PBR-123-405
Title	Monosomic analysis of Helminthosporium leaf blight resistance genes in wheat
Journal	Plant Breeding
Year	2004
Volume	123
Pages	405-409
Author	Ragiba M Prabhu KV Singh RB
Abstract	A set of 21 monosomic (2 n - 1) and the disomic (2 n ) lines of the 'Chinese Spring' cultivar were crossed with 'Chirya-3', the CIMMYT synthetic wheat line which has been identified as highly resistant for Helminthosporium leaf blight disease (HLB), in order to locate the genes governing disease resistance. The F SUB 1 and segregating populations were challenged and screened against the most virulent pure monoconidial HLB isolate KL-8 (Karnal, India). The F SUB 1 progenies of the crosses were found to be susceptible because of the recessive nature of resistance. The F SUB 2 progeny of the control cross ('Chinese Spring' x 'Chirya-3'), segregated in the ratio of 1:15 (resistant:susceptible), indicating that resistance to HLB was controlled by a pair of recessive genes. While the F SUB 2 progeny of 19 monosomic crosses segregated in the ratio of 1:15 (resistant:susceptible), the progeny of the remaining two crosses, 7B and 7D, deviated significantly from the ratio, revealing that 7B and 7D were the critical chromosomes for resistance genes that were located one on each chromosome. Moreover, the critical lines, 7B and 7D, confirmed the digenic complementary recessive nature of gene action by fitting well with the overall pooled F SUB 2 segregation ratio of 13:51 (resistant:susceptible) as expected for digenic complementary recessive resistance. The F SUB 3 segregation ratios of the critical crosses, based on their pooled F SUB 2 analysis, was estimated as 19:32:13 (non-segregating susceptible:segregating as susceptible and resistant:non-segregating resistant). F SUB 3 progenies when tested with these ratios showed goodness-of-fit, confirming that the two pairs of recessive resistance genes were located on chromosomes 7B and 7D
Keyword	genes leaves resistance wheat

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