Inheritance of Adult-Plant Resistance to Stripe Rust in Wheat

The present investigation deals with the inheritance of stripe rust resistance in varieties of common wheat. The inheritance of field resistance to races 19 and ‘A’ was studied in five varieties, viz., Cometa Klein, Gometa semiduro, Frondoso, NP 786 and NP 785. Wheat variety Kharchia was used as the susceptible parent. The genetic analysis of the varieties was based on the Fa families from backcrosses to the susceptible variety Kharchia. The data from the F^ generation of the diallel crosses of the resistant parents was utilised to establish the presence or absence of common genes in the varieties studied.

The following genes for yellow rust resistance are present in the varieties studied:

1. Cometa Klein carries two genes, YrCK₁ and YrCK₂, each of which provides resistance to both races 19 and ‘A’.

2. Cometa semiduro carries two linked genes, yrCS₁ and yrCS₂, and the former is closely linked to YrCK₁ in repulsion. Gene yrCS₁ governs resistance to race 19 and the gene yrCS₂ to race ‘A’.

3. NP 786 carries two linked genes. One of them is yrCS₁, which governs resistance to race 19 and the other is yr786₁ carrying resistance to race ‘A’.

4. NP 785 carries three genes, yrCS₁, yr785_l and yr785₂, the former providing resistance to race 19 only and the latter two to race ‘A’, with yr785₁ linked to yrCS₁.

5. Frondoso carries one dominant gene, YrF₁ which is close to the TrCK₁ locus.

A total of eight genes, six of which are in the same linkage group, have thus been identified as governing the mature plant resistance in these varieties. Gene yrCS₁ is present in Cometa Semiduro, NP 786, NP 785. Linked with yrCS₁ are genes yrCK₁, yrCS₂, yr785_1,yr786₁ and YrF₁. The remaining two genes YrCK₂ and Yr785₂ are inherited independently of the linkage group and of one another.