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Wheat Information Service
Number 91: 5-10 (2000)
Research article

Transfer of resistance to wheat pathogens from Aegilops triuncialis into bread wheat

Harjit-Singh¹, H. Tsujimoto², P. K. Sakhuja³, T. Singh¹ and H. S. Dhaliwal<sup>1

1</sup>Department of Genetics and Biotechnology, Punjab Agricultural University, Ludhiana 141004, India
² Kihara Institute for Biological Research, Yokohama City University, Totsuka-ku, Yokohama 244-0813, Japan
³ Department of Plant Pathology, Punjab Agricultural University, Ludhiana 141004, India


Summary

An interspecific cross was made to transfer leaf rust, Karnal bunt, powdery mildew and cereal cyst nematode resistance from a non-progenitor tetraploid species, Aegilops triuncialis (UUCC), into bread wheat. Sterile F₁ of the cross between susceptible Triticum aestivum cv. WL 711 and a resistant accession of Ae. triuncialis (Acc.3549) was backcrossed to the cultivated parent. Two sets of resistant derivatives were selected from selfed progenies of BC₂/BC₃plants. One group of derivatives with 42 chromosomes had spelta, type head and possessed resistance to cereal cyst nematode and powdery mildew in addition to moderate resistance to leaf rust. Giemsa C-banding of mitotic metaphase chromosomes showed that these derivatives possess a substitution of 5U chromosome of Ae. triuncialis for 5A of bread wheat. The second set of derivatives (2n=44) with disomic addition of an acrocentric Ae. triuncialis chromosome possessed leaf rust, Karnal bunt and powdery mildew resistance. Genomic in situ hybridization showed that this set of derivatives also possess a pair of translocated chromosomes involving break point in the centromere and short arm of Ae. triuncialis chromosome.


Introduction

Wild relatives of wheat have proven to be useful sources of novel genes for resistance to various diseases (Sharma and Gill 1983; Gale and Miner 1987; Jauhar 1993; Jiang et al. 1994; Friebe et al. 1996). A number of genes for resistance to various diseases and pests have been transferred from closely related as wen as distantly related species (McIntosh et al. 1998). However, many of the alien disease resistance genes transferred into wheat cultivars have been overcome, thereby necessitating the search for new sources of resistance.

Evaluation of different accessions of wild Triticum and Aegilops species maintained at the Punjab Agricultural University, Ludhiana, led to the identification of a number of new sources of resistance to wheat diseases including leaf rust, stripe rust, powdery mildew, Karnal bunt, loose smut and cereal cyst nematode (Dhaliwal et al. 1993; Gill et al. 1995;

Dhaliwal and Harjit-Singh 1997; Harjit-Singh et al. 1998). The studies showed that among the less closely related species, Aegilops species with the C, U and M genomes are excellent sources of resistance to leaf rust, stripe rust, powdery mildew, Karnal bunt and cereal cyst nematode. (Dhaliwal et al. 1991, 1993; Pannu et al. 1994; Harjit-Singh et al. 1998). Keeping this in view a wide hybridization programme was initiated to transfer the disease resistance from tetraploid Aegilops species carrying these less related genomes (Harjit-Singh et al. 1993). In the present paper, we describe the transfer of disease and cereal cyst nematode resistance genes from Ae. triuncialis into bread wheat.

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