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Genetic Analysis of Adult-Plant Resistance to Leaf Rust in Five Spring Wheat Genotypes

December 2003 , Volume 87 , Number  12
Pages  1,522 - 1,529

A. Navabi , Department of Agricultural, Food, and Nutritional Science, 4-10 Agriculture/Forestry Center, University of Alberta, Edmonton, AB, T6G 2P5, Canada ; R. P. Singh , CIMMYT, Apdo, 6-641, 06600 Mexico, DF, Mexico ; and J. P. Tewari and K. G. Briggs , Department of Agricultural, Food, and Nutritional Science, University of Alberta, Canada



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Accepted for publication 22 August 2003.
ABSTRACT

Inheritance of adult-plant resistance to leaf rust, caused by Puccinia triticina, was studied in the progeny of a one-way diallel cross involving five CIMMYT-derived adult-plant resistant wheat (Triticum aestivum) genotypes and a susceptible wheat ‘Avocet-YrA’. F1 progenies, F2 populations, F2-derived F3, and F4-derived F5 lines were field evaluated under artificial epidemics with leaf rust race MCJ/SP. Adult-plant resistance to leaf rust was incompletely dominant in crosses with the susceptible parent and was found to be controlled by additive interactions of Lr34 with at least two to three additional genes. Transgressive segregation giving rise to plants or lines with higher and lower levels of resistance than the parents was observed in all F2 and F5 derivatives of the resistant-parent intercrosses and suggested that, apart from Lr34, some of the other additive genes were nonallelic. Although specific combining ability was significant in some generations, general combining ability was found to be the major component of variation. Among generations, the estimates of the narrow-sense heritability of adult-plant resistance to leaf rust ranged from 0.67 to 0.97.


Additional keywords: diallel analysis

© 2003 The American Phytopathological Society