developing climate resilient rice through marker assisted qtl pyramiding

Abstract

he present study was undertaken with an aim of developing a multiple stress newlinetolerant version of an elite rice genotype CBMAS14065 through marker assisted pyramiding newlineof QTLs. As a first step, elite genetic stocks of CBMAS14065 harboring QTLs linked to newlinetolerance against individual stresses (drought, salinity, submergence, BLB, Blast, BPH and newlineP starvation) were developed through MABC. Attempts were made to validate the effect of newlineQTLs through precision phenotyping of early generation back cross lines. As a second step, newlineQTLs controlling tolerance against various biotic/abiotic stresses were combined into the newlinegenetic background of CBMAS14065 through novel mating designs. Effect of drought newlinetolerant QTLs of Apo was validated through phenotyping of two short duration RIL lines newlineCBMAS14076 (harboring qDTY1.1, qDTY2.1 and qDTY3.1) and CBMAS14110 (harboring newlineqDTY1.1 and qDTY3.1). Both the RILs exhibited enhanced tolerance over their female newlineparent Improved White Ponni. Superior NILs of IWP (91.8 to 95.5 % IWP genome) newlineharboring Saltol loci from FL478 were developed through MABC. Three selected BC3F4 newlineNILs of IWP (# 5-35, 5-36 and 5-45) harboring Saltol loci from FL478 exhibited better newlinegermination ability under saline conditions. All the 3 NILs were found to be moderately newlinetolerant (SES Score of 5) against 100 mM NaCl during seedling stage salinity stress whereas newlineIWP recorded SES Score of 9 (highly susceptible). Elite genetic stocks (BC2F1) of newlineCBMAS14065 harboring qDTY12.1 were developed through MABC. BC2F1 progenies of newlineCBMAS14065 introgressed with OsPSTOL1 gene from RPBio226-Pup1 were developed. newlineFour progenies (# 5-13-1, 5-13-3, 5-13-4 and 5-13-5) were found to possess 83.7 88.4% of newlinerecurrent parent genome recovery. BPH resistant genetic stocks of CBMAS14065 were newlinedeveloped through marker assisted introgression of two BPH resistant genes namely Bph20 newlineand Bph21 from IR71033-121-15B. Five BC2F1 progenies (# 1, 14, 15, 17 and 19) with RPG newlinerecovery of 80 84% were developed. Evaluation of BC1F3 progenies of CBMAS14065 newlineharboring Bph2