Genetic relationship estimation in guineagrass (Panicum maximum Jacq.) assessed on the basis of simple sequence repeat markers

Abstract

Estimation of genetic relationship for the efficient genetic resources utilization in the breeding programs of guineagrass (Panicum maximum Jacq.) is of utmost importance. Thirteen simple sequence repeat (SSR) markers, developed from genomic and cDNA clones, were successfully employed for estimating genetic relationship in guineagrass based on the analysis of 77 accessions. A genomic library enriched for (AG)/(TC) and expressed sequence tag (EST) sequences were screened for repeat motifs in guineagrass. A total of 13 SSR markers including eight from genomic clones and five from EST, were developed. Of these, eight, four and one SSR markers have perfect, interrupted and compound repeat motifs, respectively. One SSR has trinucleotide repeat motif of AGT, whereas the other 12 markers have dinucleotide motif of AG. The 13 SSR primer sets produced 1–4 amplified fragments within accessions, putatively corresponding to alleles derived from autotetraploidy of guineagrass. One hundred and ninety putative alleles were generated by 13 SSR in the 77 guineagrass accessions assayed. The values of power of discrimination (PD) ranged 0.449–0.968 with an average value of 0.859. Polymorphic information content (PIC) ranged 0.399–0.951. A phenogram of 77 guineagrass accessions obtained based on the genetic similarity with 13 SSR, revealed six major groups. The results suggested that the center of original region of guineagrass is Kenya, which agrees with an earlier study based on morphological analysis. The wide distribution of the guineagrass accessions strongly supports the assumption of intercrossing with the diploid sexual materials in natural habitat.

Genetic Diversity and Population Structure of Brachiaria Species and Breeding Populations

“…Massai, were included as an outgroup. More information about the JIRCAS P. maximum cultivars (Paikaji and Umak) is available in Ebina et al (2007). Identifying information including species, taxonomic group (Renvoize et al, 1996), geographic coordinates of the collection site, and reproductive mode is provided for the 261 genotypes included in the study in Supplemental Table S1.…”

The Present Status of C₄ Tropical Grasses Breeding and Molecular Approaches

“…The largest variations in native guineagrass emerged in accessions from its center of origin in East Africa rather than in West Africa. We attempted to obtain molecular phylogenetic data using simple sequence repeat (SSR) markers, which were consistent with the previous morphologically observed variations (Ebina et al 2007). …”

“…The progeny of 'Paikaji' have also been tested with STS-AFLP apomixis markers, revealing that there are at least eight markers strongly associated with apomixis loci in the progeny of both 'Natsukaze' and 'Paikaji'. These two cultivars are genetically distant among guineagrass accessions (Ebina et al 2007). Only a few sexual accessions have been recognized in guineagrass, so the screening and discovery of agronomically superior sexual lines of guineagrass among wild and breeding populations remains a key goal for the further development of guineagrass breeding.…”

Molecular Diversity and Genetic Structure of Guineagrass (Panicum maximum Jacq.), a Tropical Pasture Grass

“…The allelic diversity at microsatellite loci, caused by variations in the number of repeats in the core sequence, is likely caused by polymerase slippage and deficient DNA repair during DNA replication (Field and Wills 1996). Microsatellites have been proven effective for estimating genetic diversity and genetic relationships and for predicting both the genetic value of selected accessions derived from intraspecific crosses and the performance of their hybrid progenies (Varshney et al 2005;Ebina et al 2007;Chandra and Tiwari 2010). This paper presents the genetic diversity of 396 P. maximum accessions from the Embrapa Beef Cattle germplasm bank using 30 microsatellite loci.…”