Effect of single D-genome chromosome substitutions from bread wheat on spot blotch resistance of hexaploid Triticale
1998
Pfeiffer, W.H. | Duveiller, E. | Lukaszewski, A.J. | Mergoum, M. | Crossa, J.
Spot blotch, caused by Bipolaris sorokiniana, is considered one of the major diseases of triticale (x Triticosecale Wittmack), particularly in more humid agroecological zones with high rainfall. Field experiments were conducted at Poza Rica, Mexico, under natural disease epidemics over three years (1994, 1995, and 1996) to determine the effect of single D-genome chromosome substitutions from several cultivars of hexaploid wheat (Triticum aestivum L.) on spot blotch resistance of the hexaploid triticale Rhino. Coefficient of infection data across scoring dates were adjusted for growth stage and used to estimate disease severity. Substitutions 1D(1A) and 1D(1B), carrying 1D from cv. Grana, significantly contributed to higher susceptibility relative to Rhino; however, at this point it cannot be entirely excluded that 1A and 1B of Rhino both carry loci for resistance with the same level of expression. Chromosome 1 D in substitution for 1R from a hybrid of cultivars Anza and Wheaton, and concomitant absence of 1R, did not affect resistance level; however, when the long arm of 1 D from Wheaton was translocated to 1RS of Rhino, replacing 1RL, the resistance level increased. Disease reaction of recombinant chromosomes 1R.lD with long proximal and short interstitial segments of 1D for Wheaton suggests that the factor responsible for increased resistance levels is located in the distal segment of 1DL. Significantly increased susceptibility levels in substitutions 2D(2R) and 4D(4B) indicate that chromosomes 2R and particularly 4B of Rhino carry factors promoting resistance. Substitution line 6D(6B), on the other hand, was more resistant, suggesting that chromosome 6D from Chinese Spring may carry resistance.
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