GENETICS OF ADULT-PLANT HYPERSENSITIVE LEAF RUST RESISTANCE IN WHEAT
Abstract
Inheritance of resistance of wheat to Puccinia recondita was studied by making crosses between resistant and susceptible wheat breeding lines and inoculating plants in the greenhouse. F$\sb2$ and F$\sb3$ families' infection type data were analyzed for nine Purdue wheat breeding lines. Infection type data of Morocco/P74140, and Morocco/Coker 79 showed that the resistance is conditioned by two genes showing double recessive epistasis or complementary gene action. Two independent genes showing duplicate gene action controlled resistance in the cross of Morocco/P76603. Two genes with no epistatic effects conferred the resistance in the Morocco/P751915 cross. Oligogenic control of leaf rust resistance was also observed in the cross Morocco/P76779. Two genes exhibiting inhibitory gene action controlled resistance. Supplementary gene action of the two dominant genes was observed to control resistance in the cross Morocco/P77121. Two recessive genes controlled resistance in the cross Morocco/P751909, whereas two dominant genes controlled resistance in the cross Morocco/P76905. Mode of inheritance of resistance could not be determined in the cross Morocco/P75438. Effect of temperature on the above lines, as well as on P69195, a sister line of cultivar Auburn, and on the newly released cultivar Compton was studied to determine the range within which the resistance of these lines was effective. Infection types were observed at temperatures from 15 C/12 C to 30 C/21 C (day/night). Major differences in infection types were observed at both extremes in all but four lines: P75438, P76603, and P69195, which showed infection type (IT) 0 or 0c at all temperatures, and cultivar Morocco, which was consistently susceptible (IT, 3$\sp{+}$). None of the lines showed susceptible types (IT, 3$\sp{+}$) at the lower extreme of 15 C/12 C, whereas at least a few IT 3$\sp{+}$ were observed at the upper extreme of 30 C/21 C in all temperature-sensitive lines. P77121 showed a sudden loss of resistance at high temperature. Coker 79, P751909, P76905, and P76779 showed a gradual shift to higher infection types as temperature increased. P751915 remained resistant only over a narrow range. P74140 selections 6 and 7 showed a higher IT at both low and high temperatures. Cultivar Compton showed a few 3$\sp{+}$ IT at 30 C/21 D when grown continuously at that temperature regime. P69195 was crossed with 21 monosomic lines to identify the chromosome(s) responsible for resistance to P. recondita. Chromosomes 2A, 4A, 5A and 5B were identified to have recessive genes for resistance.
Degree
Ph.D.
Subject Area
Plant pathology
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