Studies on genetic distance and hybrid performance in pearl millet [Pennisetum glaucum (L.) R. Br.]
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Date
2016
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CCSHAU
Abstract
The present investigation was conducted to estimate genetic diversity at morphological and molecular
level; investigate association between genetic distance (GD) and heterosis; and to establish heterotic pool
patterns in pearl millet. To assess genetic diversity, a set of 150 (75 B- and 75 R-lines) parental lines were
evaluated for grain yield and its component traits in alpha lattice design with three replications at two agroecologically
contrasting locations in India (CCSHAU-Hisar in north India under A-zone of pearl millet
cultivation, and ICRISAT-Patancheru in peninsular India under B-zone) during rainy season of 2014; and
were also genotyped using SSR and SNP markers. Analysis of variance revealed high genetic variability for
all the traits in hybrid parents. Mean performance were higher at Patancheru location than Hisar location for
most of the traits including grain yield, except for days to flowering, plant height and panicle length. The
genetic diversity analysis based on grain yield and its seven component traits clearly partitioned all the seed
(B-lines) and restorer parents (R-lines) into two separate clear-cut groups. Many seed and restorer parents
clustering together shared common parent in their pedigrees indicating genetic similarities of clusters. Fifty
six SSR loci detected 412 alleles (average of 7.36 alleles per locus) in 147 hybrid parents of pearl millet,
while 9006 SNP loci were detected in 117 hybrid parents. Both the markers (SSR and SNP) also clustered
majority of the B- and R-lines into two clear cut separate groups indicating existence of two broad based
gene pools in pearl millet. A set of 17 diverse parents selected using SSR based genetic distance to
investigate correlation between GD and hybrid performance was used to develop a set of 136 hybrids
following diallel mating design; evaluated along with parents and standard hybrid checks for grain yield and
its component traits at Hisar and Patancheru during rainy season of 2015. Wide range of mid-parent, better
parent and standard heterosis was observed for majority of the traits. Genetic distance had low significant
positive correlation (r= 0.42) with heterosis for grain yield, but it was found higher in genetically closer
group of parents than in diverse ones. The correlation of heterosis with SSR based GD was higher than that
of GD based on SNPs or Euclidean distance (ED) and heterosis. Based on heterotic patterns, B- and R-lines
were found to be representing two broad based heterotic pools in pearl millet. Further, four (HP1, HP2, HP3
and HP4) heterotic pools for pearl millet hybrid parents were identified based on multilocation data, while
heterotic pools were found to differ for different agro-ecologies, and three heterotic pools each for A-zone of
pearl millet cultivation in India represented by Hisar location (HP1-AZ, HP2-AZ and HP3-AZ), and for Bzone
represented by Patancheru location (HP1-BZ, HP2-BZ and HP3-BZ) were identified.