Diallel analysis of the latent period of stripe rust in wheat

Abstract

A half diallel was made amongst five wheat (Triticum aestivum L.) genotypes of which one was susceptible, while the others had adult-plant resistance, to stripe rust (Puccinia striiformis West.). The five parent and ten F1 progeny were grown in the glasshouse and were inoculated with three rust pathotypes at the seedling stage. The latent period was measured on the first leaf. Two procedures were used to analyze the half diallel. Both methods showed that the average effects of alleles were of much greater importance than was dominance in conditioning resistance in response to two of the pathotypes, while for the third pathotype dominance was important. Resistance was conditioned by partial dominance for two pathotypes whereas for the third it was determined by full dominance. Broad-sense heritabilities range from 60-73% and the number of genes involved was different (from 1 to 4), depending on the pathotype.

Genetic Analysis of the Latent Period of Stripe Rust in Wheat Seedlings

“…The broad‐sense heritability estimates were high, indicating that environmental effects were quiet small on the expression of latent period (Roy, 2000). Ghannadha et al. (1995) reported similar results for the latent period of stripe rust.…”

“…On the basis of our knowledge there are, as yet, no known Yr gene(s) in the cultivars under study. Changing the mode of gene action by using different pathotypes, suggests that there is interaction between genes in the cultivars with those in the pathotypes (Ghannadha et al., 1995). Others (Johnson et al., 1986; Chen and Line, 1992a,b,c, 1993a,b; Ghannadha et al., 1995; Dehghani et al., 2002; Moghaddam et al., 2002) have also reported reversal of dominance and changes of gene interaction when different stripe rust pathotypes were used.…”

“…A range of 23–92% for heritability of slow‐rusting in small grain have been reported in the literature (Lee and Shaner, 1985a). Ghannadha et al. (1995) and Dehghani et al.…”

“…One approach towards breeding for durable resistance would be to identify the components of the resistance and use them as characters to be incorporated in a new cultivar (Johnson, 1979). The latent period is one of the most important components of slow‐rusting resistance (Parlevliet, 1975; Johnson and Wilcoxson, 1979; Lee and Shaner, 1985b; Ghannadha et al, 1995; Dehghani et al., 2002) and it can be measured with least error (Shaner et al., 1978; Kuhn et al., 1980; Shaner and Finney, 1980). The variation in latent period in stripe rust has been reported in several studies (Cromey, 1992; Ghannadha et al., 1995; Dehghani et al., 2002).…”

Wind-dispersed diseases

“…For instance, the latent periods observed for different wheat genotype and stripe rust race associations varied between 11.0 and 14.8 days (Ghannadha et al, 1995).…”