GENES OF LEAF RUST RESISTANCE IN A SYNTHETIC HEXAPLOID WHEAT

Abstract

Leaf rust (caused by Puccinia recondita f. sp. tritici) is an important disease of wheat (Triticum aestivum), and its control has been more feasible through genetic resistance. Triticum tauschii (genome DD) and Triticum turgidum (genome AABB), the wild and cultivated relatives of wheat, respectively, have been used as sources of resistance to certain diseases. To study the genetic basis of leaf rust resistance, a synthetic hexaploid (SH) wheat was derived from the cross of T. turgidum cultivar Altar 84 and T. tauschii accession-221. SH was crossed with four susceptible wheat cultivars, viz: Morocco, Chinese Spring, Opata 85, and Sonora 64. Depending on the cross inheritance studies were carried out in F₂, F₃ and BC₁F₂ generations. Results indicate that leaf rust resistance in SH is originated from Altar 84 the durum parent. SH was heterogeneous for resistance and up to three resistance genes could be detected depending on the plant used in the cross. One out of these three genes is Lr10, the second dominant
gene conferred low infection types. The third gene was recessive in nature, gave intermediate seedling reactions and was inherited with a suppressor. None of the above genes conferred enough protection to race MCJ/SP in the field.