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Wheat Information Service
Number 88: 47-51 (1999)
Research article

Transfer of Agropyron elongatum-derived resistance genes Sr25/Lr19 into Indian bread wheat cultivars

S. M. S. Tomar1 and M.K. Menon2

1Division of Genetics, Indian Agricultural Research Institute, New Delhi-110012, India
2IARI Regional Station, Wellington, The Nilgiris- 643231, India


Summary

Alien genes Lr19/Sr25 were transferred into fourteen well adapted Indian bread wheat cultivars by repeated backcrossing, All the backcross lines carrying the alien segment (Lr19/Sr25) exhibited a high degree of resistance to leaf rust and high to moderate resistance to stem rust. Backcross line WH542*6//Sunstar*6/C80-1 has however, showed TR to MR reaction to stem rust infection appearing at late maturity. The yield data recorded in three backcross lines indicated that the segment carrying resistance does not have detrimental effect on yield in certain backgrounds.

Key words: Leaf rust, Stem rust, Resistance, Backcross lines, Grain yield


Introduction

Rusts have been historically the most destructive of wheat diseases and cause substantial losses in grain yield world wide. Stem rust is highly destructive in the temperature range of 15 to 30C, whereas leaf rust rapidly develops and causes considerable destruction in the temperature range of 10 to 30C. Stripe rust is restricted to cooler regions (1 to 15C). IARI Regional Station, Wellington is situated at an altitude of 1900 m above mean sea level in the Nilgiri hills of south India with an average annual maximum temperature of 25C. All the three rusts are highly destructive throughout the year. A large number of pathotypes of Puccinia graminis f.sp. tritici and P. recondita have been reported from this place while Puccinia striiformis consists of only a few pathotypes. Genes of alien origin have more or less controlled the infection of stem rust and leaf rust in major wheat growing areas including India. This communication deals with the introgression of linked genes Sr25/Lr19 derived from Agropyron elongatum into elite Indian bread wheat cultivars which are otherwise susceptible to both stem and leaf rusts.


Materials and methods

The materials used in the present study consist of rust resistant donor Sunstar*6/C80-1, a derivative of Lr19 with highly reduced yellow pigment in the endosperm and 14 well adapted but rust susceptible Indian bread wheat cultivars (recurrent parents), namely, C 306, HD 2285, HD 2329, HD 2402, HI 1077, HUW 234, J 24, Kalyansona, Lok-1, NI 5439, PBW 226, Sonalika, WE 147 and WH 542. Since Sr25 and Lr19 are tightly linked dominant genes, five to seven backcrosses were given during a span of two to three years (raising three crops in a calendar year) and the genotypes phenotypically similar to their respective recurrent parents with resistance to stem and leaf rusts were constituted after three generations of selfing at F3 generation. Three backeross lines carrying Sr25/Lr19 were evaluated for grain yield at New Delhi farm during 1997-98. Each plot consisted of 6 meter length spaced at 23 cm. Seed rate of 100kg/ha was used. Paired t-test was applied to test the significance of difference between the two means.

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