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Wheat Information Service
Number 73: 8-10 (1991)

Transfer of leaf rust resistance from durum wheats CPAN 6051 and CPAN 6073 to Triticum aestivum

Sanjiv Gupta, A. K. Gupta and R. G. Saini

Department of Genetics, Punjab Agricultural University, Ludhiana-141004, India

Durum wheats are reported to carry leaf rust resistance genes which are different from the Lr genes identified in Triticum aestivum and very effective against highly virulent races prevalent in the Indian sub-continent (Pasquini et al 1979; Sharma et al 1986; Roelfs, personal communication). These genes can be used to broaden the genetic base of leaf rust resistance in bread wheats. Although successful transfer of genes from durum wheats have been achieved earlier for the improvement of Triticum aestivum (McIntosh et al 1967; McIntosh and Dyck 1975), an altered expression of some genes due to change in ploidy level has also been reported (Kerber 1983; Dyck 1987). We report here the transfer of resistance from two highly resistant durums CPAN 6051 and CPAN 6073 to a susceptible hexaploid wheat Agra Local and comparison of the hexaploid derivatives with two commonly grown hexaploid wheats.

Cultivars CPAN 6051 and CPAN 6073 were crossed with Agra Local. The F1s were selfed and the F2 seeds thus obtained were sown in an open experimental area under artificial epiphytotic of race 77A which is virulent on all the known genes from T. aestivum. Resistant F2 plants were identified and cytologically examined for chromosome number. A hexaploid derivative D 525-2 was isolated from cross of cultivar CPAN 6051 with Agra Local and D 3542-6 was from cross of CPAN 6073. The infection types on seedlings were recorded according to the scale given by Stakman et al (1962). The seedlings showing infection types 0;, ;, 1, 2, and X were classified as resistant and those showing infection types 3 and 4 were considered as susceptible. The terminal disease severity was recorded as percentage of leaf area covered with rust according to a modification of Cobb's scale as given by Peterson et al. (1948).

The seedling reactions (infection types) of hexaploid derivatives, the donor cultivars, susceptible parent Agra Local and two most commonly grown cultivars HD 2329 and Sonalika against leaf rust (Puccinia recondita Rob. ex Desm. f. sp. tritici) races 1, 108 and 77A and their field scores are given in
Table1. The infection types of hexaploid derivative D 525-2 and D 3542-6 against race 1 were ; and ; 1, respectively whereas those on CPAN 6051 and CPAN 6073 were ; 12+ and ; 1-, respectively. The infection types against race 108 were very close to those on durums and the derivatives. Against race 77A, the infection type on D 3542-6 was 1-1 which was very close to its donor parent CPAN 6073 (IT=11+) but that of D 525-2 varied from 2- to 3 which was different from that seen on its donor parent CPAN 6051 (1+). This difference might have appeared due to outcrossing of this derivative. Saini (1987) tested cultivar CPAN 6051 and its derivative D 525-2 against 14 Australian leaf rust races and identified Lr23 from D 525-2 as well as the donor parent CPAN 6051. However, D 525-2 was segregating for Lr13. These observation confirm outcrossing of D 525-2. Cultivar Agra Local was susceptible to all the these races and disease severity on Agra Local was 90S. The infection type on cultivars HD 2329 and Sonalika against race 1 was ;1 and ;1+, respectively. Against race 108 the infection type on seedlings of HD 2329 was ;1 but cultivar Sonalika was susceptible. Both these cultivars were susceptible to race 77A at seedling stage.


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