Integrating marker assisted background analysis with foreground selection for identification of superior bacterial blight resistant recombinants in Basmati rice

Plant Breeding (Impact Factor: 1.18). 01/2008; 127:131—139. DOI: 10.1111/j.1439-0523.2007.01458.x

ABSTRACT Basmati rice is highly susceptible to bacterial blight (BB) caused by
Xanthomonas oryzae pv. oryzae. Transfer of BB resistance genes from
non-Basmati sources to Basmati through cross-hybridization requires
strict monitoring for recovery of the desirable Basmati quality traits in
the recombinants, which show complex inheritance pattern. We
integrated background analysis using mapped microsatellite markers
with foreground selection to identify superior lines that combine useful
genes from a non-Basmati BB resistance donor line IRBB55 with grain
and cooking quality characteristics of the popular Basmati rice variety
Pusa Basmati 1(PB 1) employing backcross pedigree strategy.
Foreground selection using linked markers ensured presence of two
genes, xa13 and Xa21 for BB resistance from IRBB55, and the
recurrent parent PB 1 allele for the waxy locus giving intermediate
amylose content and maintainer allele at fertility restorer locus in the
BC1F5 recombinants. Background analysis enabled selection of
recombinants with recurrent parent genome to the extent of 86.3%
along with the quality traits. The extent of introgression of non-
Basmati donor chromosome segments in the superior selections was
estimated to be <7.8 Mb and <6.7 Mb in the xa13 and Xa21 linked
genomic regions, respectively. Association mapping identified three
quantitative trait loci, one each for 1000-grain weight, fertile grains/
panicle and cooked kernel length. The backcross-pedigree breeding
strategy facilitated recovery of additional desirable characteristics from
the donor in some of the selections. The elite selection Pusa 1460-01-
32-6-7-67 with maximum genomic background and quality characteristics
of the recurrent Basmati parent gave resistance reaction against
BB, similar to that of the non-Basmati resistant check variety and
recorded an yield advantage of 11.9% over the best check in the
multiplication agronomic trial in the Basmati growing region of India.
This line, which has been released as a new variety in the name of
Improved Pusa Basmati 1 for commercial cultivation in India, is an
example of successful application of marker assisted selection to
variety development.

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