Adult plant responses to infection with pathotype 77-5 and a mixture of important
pathotypes of Puccinia recondita were determined in the series of near-isogenic
lines/stocks each carrying a known leaf rust resistance gene and certain lines each
with a newly described stem or stripe rust resistance genes. Near isogenic lines/stocks
with single leaf rust resistance genes LrIB, Lr23, Lr36, Lr3B, Lr4I, Lr42, Lr44, Lr45,
besides Lr9, Lrl4b, Lrl4ab, Lr19, Lr2I, Lr22a, Lr24, Lr25, Lr2B, Lr29, Lr30, Lr32, Lr34,
Lr35 and Lr37 that were reported to be effective in earlier studies, exhibited partial
to complete resistance. Most of these genes, either effective throughout life or only
in adult plants, were derived from alien sources and have not so far been exploited
in Indian wheat br~eding programmes. Leaf rust resistance in a near-isogenic line
with stem rust resistance gene (Sr39) indicated additional leaf rust resistance that
is likely to be linked':with this stem rust resistance gene. Leaf rust resistance in
two of the near-isogenic lines with stripe rust resistance gene Yr24 backcrossed to
cv. Meering was partly due to Meering. Higher resistance to leaf rust in these lines
than in Meering could be attributed to additional gene(s) that may be linked with
the stripe rust resistAnce gene. Pathotype 77-5 is a very virulent strain and attacks
most of the genes for resistance to leaf rust originating from T. aestivum. Identification
of leaf rust resistances, particularly against pathotype 77-5 provided useful and
diverse sources for str:!.tegic use in future breeding programmes.
Seedling tests of the newly described resistance genes to a number of leaf rust
pathotypes identified Lr4I, Lr42, Lr44 and Lr45 as additional genes that confer
over-all resistance to leaf rust.
A number of genetically enhanced germplasm lines with different resistance genes
were developed. Two of the wheats Vaishali and Vidisha with alien resistances of
Thinopyrum ponticum (Lr24/Sr24) have recently been released and notified. Commercial
exploitation of these resistances was the first attempt in the Indian subcontinent.
Keywords: Triticum aestivum, leaf rust, genetic diversity, adult plant resistance, over-all resistance, genetically enhanced germplasm.
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906
R. N. SAWHNEY, J. B. SHARMA AND RAJESH KUMAR info_circle