Analysis of spatial distribution of genetic diversity and validation of Indian foxtail millet core collection

Abstract

Foxtail millet [Setaria italica (L.) P. Beauv.] is an important small millet, grown as a short duration, drought tolerant crop across the world. This crop can be grown on wide ranges of soil conditions and has an immense potential for food and fodder in rainfed and arid regions of the India. In the present study, 31 primer pairs (27 SSR and 4 EST-SSR) were used to analyse the genetic diversity in 223 core collection accessions. Analysis resulted in detection of a total of 136 alleles with an average of 4.38 alleles per locus. Among these 136 alleles, 22 were rare, 70 were common and 44 were frequent. The PIC value ranged from 0.01 to 0.86 with an average of 0.31. The average number of observed alleles ranged from 2.0 (northern hills of India accessions) to 4.06 (exotic) with an average of 2.72. The mean Shannon's Information Index ranged from 0.44 (northern hills of India) to 0.69 (exotic) with an average of 0.52. Pair-wise Fst values indicated little to moderate genetic differentiation among the group of accessions. UPGMA clustering grouped the accessions into two major groups while analysis for population substructure indicated presence of four subpopulations. However there was no statistically well supported grouping of the accessions based on eco-geographic specificities. The core collection designated here represented substantial genetic diversity at molecular level, hence may be a good source of diversity for use in foxtail improvement programs in the region.

Keywords: Core collection; Polymorphic loci; Setaria italica; Shannon’s information index.

Fig. 1

UPGMA dendrogram based on Jaccard's similarity coefficient among 223 accessions of foxtail millet core collection

Fig. 2

Plot of K value against delta LnPd showing optimim K = 4 (k averaged over the five run)

Fig. 3

Population structure of foxtail core collection based on 31 SSR markers showing four sub-populations with admixtures indicated in different colours

Fig. 4

Line diagram of the genetic diversity parameters (Na- Number of observed alleles; I- Shannon's information index; and Nei’s gene diversity) at the 31 SSR loci in foxtail millet core collection populations (See Table 2 for details of populations; *indicate the conserved loci)