QTL MAPPING FOR DROUGHT TOLERANCE TRAITS USING BACKCROSS INBRED LINES IN WHEAT (Triticum aestivum L.)”
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Date
2017
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DIVISION OF GENETICS ICAR-INDIAN AGRICULTURAL RESEARC INSTITUTE NEW DELHI
Abstract
Mapping population of 280 backcross inbred lines (BILs) was developed by crossing
GW322, which is a drought susceptible variety with HI1500, a drought tolerant. The BILs
population was phenotyped in three environments, namely Delhi, Indore and Powarkheda
under rain-fed condition and Irrigated condition in Delhi during Rabi 2016 in
experimental farms of Indian Agricultural Research Institute, New Delhi, IARI Regional
station Indore and Powarkheda ZARS Hoshangabad, Madhya Pradesh respectively, at
timely sown rain fed condition (2016-17). The population was evaluated for 9
phenotypic traits viz., days to heading (DH), Spike Length (SL), Plant height
(PHT),grain weight per ten spike (GWP), biomass, grain yield per plot (GY),
thousand kernel weight (Tkw); and physiological traits viz., canopy temperature (CT)
and Normalized Difference Vegetative Index (NDVI) and SPAD were carried out.
The significant variation among genotypes was observed, as revealed by ANOVA. The
normal distribution was observed for different morpho-physiological traits in the
population in all the environments indicating the polygenic control of the traits under
investigation.The transgressive seggregants were found for all traits. The formation of
four clusters following hierarchical clustering of BILs reflects the sufficient variability in
the population for QTL mapping and selection. Correlation analysis revealed the strong
positive association of NDVI, TGW, GWS, and biomass with GY under both conditions.
The CT and DH having a strong negative correlation with GY under drought stress. PCA
revealed considerable interaction between the physiological parameters in the BILs.
AMMI and GGE biplot analysis, it is evident that genotypes G20, G2, G254, G214,
G44 and G64 were the highly adapted, most stable and high yielding genotypes in all
studied environments. A total of 1050 markers were surveyed for parental polymorphism
and 122 were found to be polymorphic. The population of 188 was genotyped with 104
markers. A linkage map was constructed with 104 marker genotype data at 149 loci, using
ICIM v4. 0 software. Which is in accordance with the expected 3:1 Mendelian
segregation ratio. The maximum number of markers were found on 2B with 14
markers while lowest being 1A chromosome. The average numbers of markers per
chromosome were 7.09 with average marker interval of 29.59cM. To identify
genomic regions governing drought tolerance Single marker analysis (SMA) and
Inclusive composite interval mapping (ICIM) was performed, and total of 44 QTLs were
detected on 17 chromosomes. Three QTLs were detected for DH, 4 QTLS for PHT, 1
QTL for SL, 3 QTLs for GWS, 13 QTLs for NDVI, 6 QTLs for CT, 3 QTLs for
Biomass, 5 QTLs for TKW, 3QTLs for GY and 4 QTLs for HI. The number of QTLs
per trait ranged from 1 QTLs for SL to 13 QTLs for NDVI. Chromosomal region
affecting NDVI were distributed on 8 chromosomes. The identified QTLs can be used
in Marker assisted breeding programme for drought tolerance improvement in wheat
after fine mapping and validation.
Description
t-9823
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