Genetic diversity of Napier grass (Pennisetum purpureum Schumach.) in Western Kenya; implication on Napier stunting disease resistant breeding

Abstract: Napier grass (Pennisetum purpureum Schumach.) is an allotetraploid (2n = 4x = 28) and has a genome formula of A’A’BB, where A’A’ is homologous to the AA genome of pearl millet (2n = 2 x = 14) Pennisetum glaucum (L). It is the dominant livestock fodder in all stall feeding systems in Kenya and has numerous other applications. Candidate clones for Napier stunt disease resistance need to be diverse in order to increase the probability of having resistant genes within a given population. In this study, the diversity of Napier grass was assessed in relation to Napier stunt disease using simple sequence repeat (SSR) markers derived from other related plants in the Pennisetum genus which included pearl millet, sorghum and maize. A total of 96 samples were studied using 25 selected SSR markers. The results showed that 90% of the molecular variation in Napier grass populations exists among individuals within a given population, while 1% is encountered between populations. There was no distinct population structuring in the five populations studied. This study recommends increasing the level of diversity in the Western Kenya Napier grass germplasm through introductions of new Napier clones and proper selection to increase the chances of getting resistant genes to Napier stunt disease.