Discovery and Utilization of EST-SSR Marker Resource for Genetic Diversity and Population Structure Analyses of a Subtropical Bamboo, Dendrocalamus hamiltonii

Dendrocalamus hamiltonii is a giant bamboo species native to Indian subcontinent with high economic importance. Nevertheless, highly outcross nature and flowering once in decades impose severe limitation in its propagation. Identification and mixed cultivation of genetically diverse genotypes may assist successful breeding and natural recombination of desirable traits. Characterization of existing genetic diversity and population structure are indispensable for efficient implementation of such strategies, which is facing a major challenge due to non-availability of sequence-based markers for the species. In this study, 8121 EST-SSR markers were mined from D. hamiltonii transcriptome data. Among all, tri-repeats were most represented (52%), with the abundance of CCG/CGG repeat motif. A set of 114 polymorphic markers encompassing epigenetic regulators, transcription factors, cell cycle regulators, signaling, and cell wall biogenesis, detected polymorphism and interaction (in silico) with important genes, that might have role in bamboo growth and development. Genetic diversity and population structure of the three D. hamiltonii populations (72 individuals) revealed moderate to high-level genetic diversity (mean alleles per locus: 5.8; mean PIC: 0.44) using neutral EST-SSR markers. AMOVA analysis suggests maximum diversity (59%) exists within population. High genetic differentiation (G(st) = 0.338) and low gene flow (N-m = 0.49) were evident among populations. Further, PCoA, dendrogram, and Bayesian STRUCTURE analysis clustered three populations into two major groups based on geographical separations. In future, SSR marker resources created can be used for systematic breeding and implementation of conservation plans for sustainable utilization of bamboo complex.