New sources of leaf rust resistance in Indian local durum wheat
B.K. Honrao1, S.C. Misra1*, S.K. Nayar2, R.N. Dixit1, A.M. Chavan1 and V.S. Rao1
1Agharkar Research Institute, G G Agarkar Road, Pune 411 004 (India)
2DWR Regional Research Station, Flowerdale, Shimla, (India)
Leaf rust (Puccinia triticina Eriks. = P.recondita f.sp.tritici) is the most important disease of wheat. Race 77 complex of leaf rust has knocked down almost all the present bread wheat varieties in the country, creating an alarming situation. Durum wheats showed high levels of resistance to the leaf rust race 77 pathotypes (Pandey and Rao 1984; Honrao and Rao 1996; Nayar et al. 1996; Sharma et al. 1996). Identification of appropriate pathotypes of leaf rust for evaluating resistance in seven Indian local durum wheats was carried out based on seedling tests of 33 currently evolved pathotypes as well as their field response during 1997-2002 seasons. Hence, it is important to identify new germplasm for breeding of durums possessing resistance to leaf rust. The present communication reports seven new genetic stocks of Indian local durums with leaf rust resistance; A090, Dasarkhed-1, Haura, Bansi-288-18, Bijaga red, Bansi 207-3 and Malvi local (Table 1).
These varieties showed high level of field resistance with mixture of races at Pune during 1997-2002 with artificial epiphytotic conditions (Table 2).
Seedling response to 33 important Indian leaf rust pathotypes were also evaluated along with suitable checks at 20 ± 2°C temperature and 80% relative humidity controlled conditions by using standard procedure (Stakman et al. 1962) and further tested at DWR Regional Research Station Simla for confirmation. Differences in seedling response of durum wheat lines to 33 test pathotypes of leaf rust (Table 3).
Six of seven durum lines were highly resistant to all biotypes of race 77 and other pathotypes at seedling stage except Bijaga red, which was susceptible to 77-6(121 R 55-1). All local durums showed susceptible reaction to weak pathotypes viz. 11(0R8), 12 (5R%) and 104 (17R23). However, the pathotype 77-5 (121R63-1) was avirulent to all the local durum lines. In contrast, the leaf rust pathotypes 11,12,104 and 106, presumed to be weak pathotypes due to their low levels of virulence to known leaf rust resistance genes, were more virulent to durums, compared to bread wheats.
As mentioned above, these local durums being promising for seedling as well as field resistance to leaf rust and possess desirable agronomic and quality characteristics, their use as breeding stocks for leaf rust resistance-cum-quality wheat breeding is suggested. The resistance from durums may be exploited to widen the genetic base of resistance in bread wheat.
References
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Nayar SK, Prashar M, Kumar J, Bhardwaj SC and VermaLR (1996) Distribution pattern of Puccinia recondite tritici pathotypes in India during 1990-94. Ind J Agri Sci 66(10): 621-630.
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