Assessing the cross transferability of finger millet SSR markers and
genetic diversity analysis in browntop millet (Brachiaria ramosa L.)
based on microsatellite data and morphological traits
Abstract
Browntop millet (Brachiaria ramosa L. Stapf) holds cultural and
agricultural significance in Southern India, serving as both a staple
food for humans and fodder for livestock. Recently, its high fiber and
protein content has gained public attention, making it popular as a
nutritious grain. However, despite its nutritional benefits, the limited
genomic information available for browntop millet has hindered breeding
efforts. To address this knowledge gap, an assessment was made to test
the transferability of SSR (Simple Sequence Repeat) primers from finger
millet to browntop millet, aiming to identify genetic polymorphism. In
this study, 27 accessions of browntop millet were subjected to SSR
analysis using 100 SSR primers developed for finger millet. Among the
100 primers tested, five were mono-nucleotide, 38 were di-nucleotide, 42
were tri-nucleotide, and 15 were tetra-nucleotide repeats. Initial
screening of 100 primers on 100 primers on two browntop millet
accessions GPUBT-2 and IC617953 showed 40 per cent and 42 per cent
transferability. Among the 30 amplified primers screened on both
browntop millet genotypes, one was a mono-nucleotide repeat, 16 were
di-nucleotide repeats, and 13 were tri-nucleotide repeats. The analysis
revealed that di-nucleotide repeats were the most common repeat type. 30
primers which showed amplification in both genotypes were used for
screening 27 browntop millet genotypes. The PIC values of all the
polymorphic loci for 25 browntop millet genotypes varied from 0 to 0.68,
major allele frequency varied from 0.40 to 1, allele number varied from
1 to 5 and genetic diversity varied from 0 to 0.72. Cluster analysis
combining morphological and molecular markers based on UPGMA method
resulted in two major clusters. These findings demonstrate the potential
for utilizing genomic resources from related millet species and
highlight opportunities to enhance browntop millet breeding programs.