Inheritance of Latent Period of Puccinia recondita in Wheat
- Gregory Shaner ,
- George Buechley and
- Wyman E. Nyquist
Long latent period, a major component of slow leaf-rusting resistance in wheat (Triticum aestivum L.), was studied in the progeny of a cross between cultivars CI 13227 and Suwon 92. F2 plants and F3-and F6-derived F7 families, each derived from a different F2 plant by single-seed descent, were evaluated for latent period of infection by Puccinia recondita Roberge ex Desmaz. There was a wide range in latent period among F2 plants and highly significant differences in latent period among families. The distributions of latent period for F2 plants and F3 and F7 family means were skewed to the right, and population means were significantly below midparental values. The data suggested that four loci with epistatic effects controlled latent period. Because approximately three-fourths of the F7 families had values below the midparental value, it appeared that a gene at one of the four loci exerted a major effect on latent period. Although latent period is a quantitative trait, narrow-sense heritability of an F2 individual was fairly high, ranging from 0.64 to 0.98, and the trait could be measured with acceptable precision by visual estimation of the percentage of infection sites that had erupted into pustules at each day after inoculation. Selection for the trait could begin in the F2 generation, but desirable phenotypes will continue to segregate in later generations from somewhat susceptible plants, so it may be advisable to carry bulk populations for several generations from which fairly homozygous, slow rusting plants may be selected.
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