Genetic relationships among napiergrass (Pennisetum purpureum Schum.) nursery accessions using AFLP markers

Abstract

Pennisetum purpureum Schum. (napiergrass) is a perennial grass used for forage especially in South America and Africa. Over the last 30 years, a USDA -ARS nursery containing accessions collected from all over the world has been established in Tifton, Georgia. The study reported here was conducted to assess the molecular genetic variation and genetic relatedness among 89 accessions from the Tifton nursery using amplified fragment length polymorphism markers, morphological data and ploidy level. Using 218 polymorphic markers from eight selective primer combinations, the 89 accessions were clustered into five groups using a principal components analysis and a dendrogram based on Dice similarity estimates and unweighted pair group method with arithmetic average clustering. These five groups include three groups collected from Kenya, a group from Puerto Rico, and accessions derived from the cultivar Merkeron. This research provides the first molecular characterization of the Tifton nursery, displays the relationships between accessions, and provides potential heterotic groups for napiergrass and pearl millet (Pennisetum glaucum (L.) R. Br.) breeding improvement.

Opportunities for Napier Grass (Pennisetum purpureum) Improvement Using Molecular Genetics

“…In addition, clustering of the accessions into five groups in line with geographical origin was observed, which was a similar result to that observed using RAPD markers [11]. However, in another study using AFLP markers, Napier grass accessions of different geographical background obtained from research centres in Botswana, Mozambique, Ghana, South Africa, and Ethiopia (ILRI forage genebank collection) came together into different groups, with no clear evidence of clustering according to geographical origin [43].…”

“…Napier grass is a cross-pollinating allotetraploid species with a chromosome number of 2n = 4x = 28 (genome A'A'BB) [11,31,32]. Although there is no clear information on the genetic origin of allotetraploidy in Napier grass, the A'A' genome has been reported to be homologous to the AA genome of pearl millet (Pennisetum glaucum (L.)) and the A' chromosomes are larger than the B chromosomes, which contribute genes controlling the perennial growth habit [31].…”

“…For example, accessions were screened for resistance to diseases, and Napier grass head smut-and stunt-resistant lines were identified from the existing collections [33,34]. Plant breeding and selection in Napier grass has primarily been aimed at improving different agronomic traits such as disease resistance, yield, nutritional quality, growth habit (dwarfing), palatability and abiotic stress tolerance [6,11,35]. Napier grass is cross-compatible with the closely related species pearl millet (Pennisetum glaucum) (2n = 2x = 14, genome AA) [6,15]; the resultant hybrids are triploid and sterile [6] and can only be propagated by vegetative means which, although labour intensive, ensure a true-to-type variety [15].…”

“…Harris et al [11] were able to study the genetic relationship among 89 nursery accessions using amplified fragment length polymorphism (AFLP) markers and the results revealed a moderate to high degree of genetic relatedness among the accessions. In addition, clustering of the accessions into five groups in line with geographical origin was observed, which was a similar result to that observed using RAPD markers [11].…”

Genetic diversity and relationship of sainfoin (Onobrychis viciifolia Scop.) germplasm as revealed by amplified fragment length polymorphism markers

“…Second, it is more efficient for detecting polymorphisms and more informative than RAPD and ISSR (Powell et al 1996;Loh et al 2000). Third, AFLP-based genetic diversity analyses have been successfully demonstrated in many forage crops (Ferdinandez and Coulman 2002;Fu et al 2004;Peng et al 2008;Harris et al 2010;Biligetu et al 2013).…”