IDENTIFICATION OF QTLs CONTROLLING DROUGHT TOLERANCE, YIELD TRAITS AND BLAST RESISTANCE IN RICE (Oryza sativa L.) RECOMBINANT INBRED LINES (RILs)
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Date
2013-07-15
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University of Agricultural Sciences, GKVK
Abstract
Rice is a staple food crop which provides calorific needs of millions
of people in Asian countries. Due to resilient climatic changes rainfall
has been very erratic, unseasonal and disease outbreaks are dynamic.
Considering drought and leaf blast disease as the major production
constraints, the research was undertaken to detect quantitative trait loci
(QTLs) controlling the drought tolerance and leaf blast resistance. A
mapping population of 281 RILs derived from HPR-14 (Drought tolerant
and blast resistance) and BPT-5204 (Agronomically superior variety) were
screened in two replications for drought tolerance at UAS Bengaluru and
for leaf blast response at disease hot spot, ARS Ponnampet in kharif
2012. RIL No. 616, 861 and 2386 transgressed their parents and checks
(Rasi and MAS 946-1) under aerobic and moisture stress condition. Out
of 281 RILs, 38 RILs were found to be resistant to leaf blast infection. A
SSR linkage map covering 1159 cM of rice was constructed using 112
polymorphic markers. Composite interval mapping of QTLs with LOD ≥
2.4 revealed 54 QTLs linked to plant phenology, yield related traits and
drought traits under aerobic and moisture stress condition. A genomic
region identified on chromosome 3 harboured QTL (R2=7.10%) for grain
yield under moisture stress condition. The genomic region flanked by RM
5626-RM282 and RM271-RM304 marker intervals on chromosome 3 and
10 identified for yield water use efficiency that colocated with QTLs
associated with yield per day and per cent spikelet fertility under
moisture stress conditions. Three independent QTLs were detected for
leaf blast on chromosomes 4 and 12. The novel QTLs explained relatively
high phenotypic variance for grain yield traits, drought contributing
traits and leaf blast resistance which can be deployed for pyramiding
QTLs to improve rice varities for durable drought tolerance and broad
spectrum resistance against the leaf blast fungus.
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Keywords
yields, developmental stages, grain, planting, rice, biological phenomena, genetics, weather hazards, chromosomes, phenotypes