Abstract
Occurrence of multiple abiotic stresses in a single crop season has become more frequent than before. Most of the traditional donors possessing tolerance to abiotic stresses are tall, low-yielding with poor grain quality. To facilitate efficient use of complex polygenic traits in rice molecular breeding research, we undertook development of introgression lines in background of high-yielding, semi-dwarf varieties with good grain quality. The study reports the development and evaluations of over 25,000 introgression lines in eleven elite rice genetic backgrounds for improvement of yield under multiple abiotic-stresses such as drought, flood, high/low temperature. The developed introgression lines within each genetic background are near isogenic/recombinant inbred lines to their recipient recurrent parent with 50 to 98% background recovery and additionally carry QTLs/genes for abiotic stresses. The multiple-stress tolerant pyramided breeding lines combining high yield under normal situation and good yield under moderate to severe reproductive-stage drought, semi-dwarf plant type with good grain quality traits have been developed. The introgression lines in dwarf backgrounds open new opportunity to improve other varieties without any linkage drag as well as facilitate cloning of QTLs, identification and functional characterization of candidate genes, mechanisms associated with targeted QTLs and the genetic networks underlying complex polygenic traits.
Highlights
IntroductionTo study the background recovery of the selected introgression lines, background genotyping was carried out
Swarna-Sub[1]Introgression line QTLs (BCR) % SS MS NSSub qDTY1.1 + qDTY2.1 + qDTY3.1 + Sub[1]qDTY1.1 + qDTY3.1 + Sub[1 ] qDTY3.1 + Sub[1]IR 102793:1-11-229-3-1-1
The near isogenic lines with one, two, three and more QTLs have been developed in -eleven different elite backgrounds by the integration of phenotypic-genotypic selection approach
Summary
To study the background recovery of the selected introgression lines, background genotyping was carried out. The background recovery percentage (BC%) of the selected introgression lines in different backgrounds were calculated as Vishwakarma et al.[87]. The experiment means and SED (standard error of difference) were calculated using the statistical software. The LSD (Least significant difference) at P = 5% and 1% significance were used to make the comparison of the test entries means and to estimate the significant differences of the traits of interest between the parents and the introgression lines. The mixed linear model was used to calculate the analysis of variance: Yijk = μ + Gi + Rj + BK Rj + eijk where μ is the overall mean, Gi is the effect of i th genotype, Rj is the effect of jth replicate, BK (Rj) is block effect of the jth replicate and eijk is the error. Genotypes were kept as fixed and the replication and block effects were kept random for estimating entry means
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