| dc.description.abstract | Hybrid rice cultivation has expanded slowly in India and other countries in Southeast
Asian because of the high cost of F1 seed production, poor grain quality, yield heterosis, and
biotic and abiotic stresses.
This study aims to determine the genetic association between QTLs that regulate brown
plant hopper (BPH) resistance (for protecting the rice (Oryza sative L.) crop from “hopper
burn”), photoperiod response of heading date, and pollen number (for enhancing seed set in
female cytoplasmic male sterile parents). This study also seeks to identify high heterotic restorer
lines in a recombinant inbred line (RIL) population derived from Bayer restorer germplasms
BRGB02489 and BRGB04267.
A genetic association between the host plant and insect was revealed upon BPH nymph
infestation with the identification of a major additive (A) effect QTL on chromosome 4 (qBP4),
while significant differences were found for antixenosis and antibiosis modes of insect resistance
in genotypes carrying qBP4-resistant alleles.
The heading date data of the RIL population was evaluated in seven wet- and dry-season
environments at latitudes 17.4ºN (Chandippa) and 29.9ºN (Dhantori). Out of 21 putative QTLs
mapped across chromosomes 3, 4, 6a, 6b, 7 and 11, the major A effect QTL located between 0.0
cM and 26.7 cM on chromosome 6b was associated with early and late flowering behavior
independent of photoperiod changes, while a photoperiod-sensitivity QTL was identified on
chromosome 6a with degree of photoperiod sensitivity data. The results of a genetic analysis
study based on heading date data suggest that it is possible to breed for stable and early
flowering restorer lines by introgression of the BRGB04267 allele for the QTL on chromosome
6a and the BRGB02489 allele for the QTL on chromosome 6b. The least mean square data of
pollen number (pollen load) of the RIL population indicated that significant difference among
genotypes, and the major additive effect QTL associated with high pollen load was mapped on
chromosome 9 (qPL9).
A linear mixed model analysis was conducted with ASReml in order to derive the best
linear unbiased predictor (BLUP) value, and the RILs BYRIL117, BYRIL026, BYRIL055,
BYRIL060, BYRIL073, BYRIL140, BYRIL228, BYRIL072, and BYRIL020 were identified as
providing notable yield advantage in hybrids derived from testers BRGB07288A and
BRGB06355A.
The present study is an example of an exploration of multiple traits from a single donor.
Development of functional single nucleotide polymorphisms (SNPs) associated with BPH
resistance, heading date, photoperiod sensitivity and pollen load could facilitate marker-assisted
breeding in order to improve germplasms for stable flowering behavior, high pollen load and
BPH resistance. | en |
