TAXONOMIC IDENTIFICATION OF ELEUSINE SPP. USING PLASTID GENES

Abstract

Finger millet (Eleusine coracana subsp. Coracana) is a very promising crop to alleviate the problems of food scarcity and malnutrition in the semi-arid tropics and beyond because of its known wide ecological adaptability and nutritional standards yet its production is much less than the demand. This necessitates intensive breeding programmes to improve its production and quality. Analysis and detection of the existing variability and relatedness among cultivated crop species and their immediate wild relatives are important initial steps in breeding. The wild relatives are a source of novel genes that could be exploited in improving the cultivars through introgression among other breeding methods. This necessitated this phylogenetic study. The research involved extracting DNA from two to three weeks old seedlings of 97 wild accessions of genus Eleusine from eastern Africa regions of Ethiopia, Uganda, Kenya and Tanzania (believed to be the primary centre of diversity) and 3 cultivated accessions and amplifying the regions of chloroplast DNA using both forward and reverse primers for the three chloroplast barcodes rpl32-trnL intergenic-spacer, ndhF gene and rps3 gene. The amplicons were sequenced and the nucleotide sequences of the regions used to discriminate among the genotypes and to construct phylogenetic trees (Phylograms). Evaluation of the three chloroplast barcodes revealed some relatedness among them and further elucidated their overall relatedness to the cultivated finger millet. The study also mainly supported but occasionally refuted previous taxonomic classification (based on phenotypic – cytological and morphological – characters) of some genotypes e.g. accession AAU-ELU-22 was most likely multiflora with 97% bootstrap support and not intermedia as previously classified. The results of the primers ndhF and rpl32-trnL generally showed E. floccifolia, E. jaegeri and E. multiflora being closely related while E. coracana, E. indica. E. africana and E. kigeziensis formed another clade. This generally forms two clades, the E. floccifolia and E. indica clades. The E. indica clade was more related to the cultivated accessions than the E. floccifolia clade. The rps3 primer was less informative.