Construction of High-Density Genetic Linkage Map of Napiergrass (Pennisetum purpureum).

Napiergrass (Pennisetum purpureum Schumach) is one of the highest yielding tropical forage grass and a promising lignocellulosic biofuel feedstock owing to its high biomass, nutritive value, and yield. However, its utilization for breeding has been lagging other crops due to limited genomic studies and unavailability of reference genome and linkage maps. In this study, next-generation sequencing approach was used to carry out the genome survey of napiergrass and a high-density linkage map was constructed. Genome sequence of napiergrass showed high synteny to the genome of pearl millet which could be used as a reference genome for mapping in napiergrass. For the linkage map, 1,917 markers were grouped into 14 linkage groups spanning a length of 1473.94 cM and a density of 1 marker per 0.76 cM. Using multiple programs (TASSEL, GBS-SNP-CROP, STACKS, Freebayes, Samtools, and GATK) for de-novo and reference based SNP identification, we present the first genetic map of napiergrass which can be used for genome assembly, genetic improvement, and comparative genomics research.