Detection of responsible resistance genes to stem rust (Puccinia graminis f. sp. tritici)‎ in some Egyptian wheat cultivars

Abstract EN

Genes for resistance to stem rust (Puccinia graminis f.

sp.

tritici) were postulated in eighteen Egyptian wheat cultivars.

The reactions of the tested cultivars were compared to the reactions of 20 monogenic lines (Sr's) against 25 known pathogenic isolates of the causal organism.

Difference and similarity of the reactions in terms of infection types (I T's) between the monogenic lines and the tested cultivars was used to postulated gene (s) responsible for seedling resistance.

Gene postulation showed that no stem rust resistance gene (s) could be detected in the two cultivars; Giza 160 and Sakha 93.while , Misr 1 cv probably has most of the tested genes (18 genes), followed by Gemmeiza 10 and Banisweif 6 (each probably has 16 genes), Sakha 95 (15 genes) and Gemmeiza 7, Gemmeiza 11, Sids 13 and Shandaweal-1 (14 genes probably present in each).

Also, eleven and twelve Sr genes were probably present in Misr-2 and Sakha 94, respectively.

The other cultivars under study, probably have a few numbers of the tested genes.

Some of the postulated genes were common in most of the studied cultivars i.e., Sr30, Sr 17, Sr 9e, Sr 10, Sr 36 and Sr 13, in which other genes were not in common.The most effective stem rust resistance genes which showed very low virulence frequency (%) were Sr’s 13, 7a, 9e, 9d and 21.

While high occurrence of virulence frequency (%) were found agains Sr's 8b, 6, 10 ,9a, 9g, 9b, 17, 5, 7, 11 and 8b.

So, these Sr genes considered to be the least effective genes against the tested isolates of the causal pathogen.

The prompt detection of genes conditioning stem rust resistance in wheat cultivars and advanced or promising germplasma complemented or coupled with multilocational evaluation for adult plant resistance (APR) or field resistance, will enable wheat breeders to make well founded decision in relation to planning successful breeding strategy, that aimed to release a new wheat variety with a long- lasting and more durable resistance against wheat stem rust disease.