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Wheat Information Service
Number 75: 41-45 (1992)


Inheritance of resistance to leaf rust (Puccinia recondita f. sp. tritici ) in two durum wheats

Sanjiv Gupta1, A. K. Gupta2 and R. G. Saini3


Department of Genetics, Punjab Agricultural University, Ludhiana-141 004, Punjab, India


Summary

Inheritance studies were conducted on two leaf rust resistant durum wheats. Triticum durum cvs. Malvika and CPAN 6051 were crossed with susceptible durum wheat Malvi Local. The F2 and F3 generations were tested against leaf rust races 1, 77 (biotype A) and 108. Single dominant gene was effective against race 108 and two independently inherited dominant genes were effective against each of the races 1 and 77A in cultivar Malvika. Cultivar CPAN 6051 carried single dominant gene against races 1 and 108, whereas two independently inherited dominant genes were operative against race 77A. At least one resistance gene was common in cultivars Malvika and CPAN 6051.


Introduction

Breeding resistant cultivars depends primarily upon the availability of diverse and effective resistance genes. Sources of resistance to leaf rust caused by Puccinia recondita f. sp. tritici have been identified both from Triticum aestivum (Gras 1980, Zitelli et al 1981, Tomerlin et al 1984, Dyck et al 1987) and Triticum durum (Leonari 1973, Mishra et al. 1989, Casulli et al 1983). Durum wheats have been identified as donors of new leaf rust resistance (Lr) genes which are effective against highly virulent races like 77 and 104 prevalent in the Indian sub-continent (Sharma et al. 1986). Durum wheats also contribute towards superior quality characteristics (Quick and Crawfod 1983). Identification of Lr genes in Triticum aestivum is based on allelic tests with near isogenic lines developed in the background of cultivars Thatcher and Prelude (Dyck and Samborski 1970, Samborski and Dyck 1976, Dyck 1977). Such testers with designated genes are not available for durums, therefore, only temporary designations have been given to Lr genes identified from T. durum (Ataullah 1969, Statler 1972). The present report deals with the inheritance of resistance and allelic relationship between Lr genes from two important durum wheats.


Material and methods

The experimental material comprised of two highly resistant durum wheats namely Malvika and CPAN 6051, and a susceptible cultivar Malvi Local. The pedigree, seedling reactions against race 1, 77 (biotype A) and 108 and the field scores of these wheats in an epiphytotic of race 77A are given in
Table 1. Both resistant wheats were crossed to the susceptible cultivar Malvi Local. The F2 and F3 generations obtained from these crosses were tested against leaf rust races 1, 77A and 108 at seedling stage under controlled conditions in a growth house maintained at 20 plus or minus 1oC. Simple chi2-test was applied to test the goodness of fit of different genetic ratios. Race1 is avirulent on all the Lr genes from T. aestivum except Lr20 and Lr23 from T. durum both on seedlings and adult plants. At seedling stage race 77A is virulent on all the Lr genes from T. aestivum, but the adult plants carrying genes Lr12, Lr14b, Lr23 and Lr27 + Lr31 from Triticum aestivum are resistant. Race 108 is also virulent on all the Lr genes from T. aestivum except Lr3 and Lr15 at seedling stage. The adult plants carrying Lr3, Lr12, Lr13, Lr14a, Lr14b, Lr16, Lr17, Lr22, Lr22b, Lr23, Lr27 + Lr31 and Lr30 are resistant to this race.

The two resistant durums were also intercrossed and the F2 generation seedlings thus obtained were studied against races 1, 77A and 108 to establish allelic relationship between genes from these two wheats.

The infection types were recorded 14 days after inocultaion of seven day old seedlings according to a modification of the scale given by Stakman et al (1962).


1 Biotechnology Centre, Punjab Agricultural University, 2 C. S. 1. R. Complex, Palampur, Himachal Pradesh, India, 3 Corresponding author

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