IDENTIFICATION OF DROUGHT TOLERANT RICE (Oryza sativa L.) GENOTYPES FOR RAINFED LOWLAND ECOLOGY USING MICROSATELLITE MARKERS LINKED TO DROUGHT
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Date
2014
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Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
Drought is referred to as low-moisture stress or is a form of abiotic stress
which is a challenge posed by the environment to the survival and productivity of a
crop that occupies a large area. The development of drought tolerant rice varieties
is considered a feasible option to counteract drought stress. However the breeding
efforts to develop varieties with improved productivity are being hindered due to
lack of understanding of inheritance of drought tolerance and poor understanding
of physiological basis of yield under water stress. The aim of the present study was
to select drought tolerant genotypes from the F6 population of a cross between
BPT-5204 (drought susceptible) and Sahbhagi Dhan (drought tolerant) in lowland
ecology by the use of morphological markers and MAS (Marker Assisted
Selection) with SSRs available in the public domain. Screening of Eight Hundred
and Ten Recombinant Inbred Lines (RILs) for drought was carried out under
rainout condition. Stress was imposed for 5 weeks at vegetative stage of the crop to
screen for drought tolerant lines. Experimental results based on the observations of
leaf rolling, leaf drying and recovery identified 140 highly drought tolerant lines.
Mean, variability and correlation studies were made based on the observations
recorded for various morphological and yield attributing characters. As per the
statistical analysis there was substantial variation among the traits. Further, 20
phenotypically highly drought tolerant RILs were selected for root studies and
molecular studies using microsatellite markers linked to drought. 19 SSR primers
were used to screen for parental polymorphism, out of which 6 showed
polymorphism. The drought tolerant lines confirmed using these six polymorphic
SSRs were line numbers 4, 122, 125, 135, 137, 152, 161, 162, 165, 179, 180, 181,
193, 194, 205, 418, 586, 808, 809 and 810. Among the 20 drought tolerant
genotypes, the maximum yielding lines were line number 4, 137, 181, 193 and 808
with medium maturity duration. Molecular studies revealed the presence of
maximum of 4 QTLs for drought in a single genotype. However, the drought QTLs
detected were on chromosomes 1, 3, 4, 5, 6 and 7. These QTLs were linked to
various characters like plant height, panicle length, grain yield, root thickness, root
length, root volume, root to shoot ratio, days to 50% flowering, biomass, harvest
index and test weight.
Description
IDENTIFICATION OF DROUGHT TOLERANT RICE (Oryza sativa L.)
GENOTYPES FOR RAINFED LOWLAND ECOLOGY USING
MICROSATELLITE MARKERS LINKED TO DROUGHT
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