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Wheat Information Service
Number 92: 20-24 (2001)
Research article


Transfer of Agropyron elongatum-derived rust resistance genes Sr24 and Lr24 into some Indian bread wheat cultivars

M. K Menon1 and 8. M. S. Tomar2

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


Summary

Agropyron elongatum-derived linked rust resistance genes Sr24 and Lr24 were transferred into nineteen elite Indian bread wheat (Triticum aestivum L.) cultivars, namely, Sonalika, Kalyansona, NI 5439, C 306, WH 147, Lok-1, HD 2329, HD 2285, J 24, HD 2009, VL 421, UP 262, WL 711, HUW 234, PBW 226, HD 2402, HI 1077, HS 240 and WH 542 through backcrossing. Gene Lr24 conferred total resistance to leaf rust, whereas a new virulence for Sr24, namely, 40-1 rendered the gene ineffective against stem rust. The chromosome segment carrying genes Sr24 and Lr24 imparted enhanced resistance to Barley Yellow Dwarf Virus (BYDV). The segment was also associated with terminal clubbiness of spikes.

Key words: Triticum aestivum, bread wheat, leaf rust resistance, backcrossing, cultivar


Introduction

Extensive investigations on near-isogenic lines of wheat (Triticum aestivum L.) cultivar Thatcher and wheat stocks carrying known specific genes for resistance to rusts have revealed that resistance genes Sr24, Sr26, Sr27, Sr31, Sr32, Sr36, SrAgi and Lr9, Lr19, Lr24, Lr28, Lr32, Lr37 (Tomar and Menon 1998) are highly effective against stem and leaf rust pathogens in India. The lines carrying these genes were screened under natural and artificially created rust epiphytotics at Wellington, an important hotspot for rusts in the southern hills of peninsular India. The weather conditions in these hills are very congenial for host and pathogens and the rusts are highly destructive throughout the year. A wide spectrum of stem and leaf rust pathotypes are prevalent in these hills (Bahadur 1986; Nayar et al. 1988). The authors have taken up an elaborate and comprehensive backcross program since 1983 to introgress alien genes conferring resistance to leaf and stem rusts into widely adapted and popular Indian bread wheat.

The tightly linked genes Sr24-Lr24 originating from Agropyron elongatum (now Lophopyrum elongatum) confer resistance to stem and leaf rusts. Because of their linkage with red kernel color in cultivar Agent they could not be utilized in Indian subcontinent where the red grains were not commercially acceptable. However, one of the white seeded recombinant line TR 380-14*7/3Ag#14 (McIntosh and Partridge pers comm) proved to be a valuable stock for developing backcross lines. This article deals with the introgression of Agropyron elongatum-derived linked genes Sr24 and Lr24 into 19 Indian bread wheat cultivars, which are highly susceptible to leaf rust.

2 Corresponding author

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