Genome Analysis of Finger Millet E. coracana by Interspecific Hybridization among Diploid Wild Species of Eleusine (Poaceae)

抄録

Four species of Eleusine viz. E. intermedia, E. floccifolia, E. indica and E. tristachya are wild diploid taxa (2n=2x=18) and are presumed to have contributed to the evolution of finger millet, E. coracana, the amphidiploid with AABB genome (2n=2x=36) and an important minor millet grown in Africa and South Asia. E. indica is known to have contributed the A genome to E. coracana, while the information regarding the other genome donor species is not forthcoming. The present investigations were undertaken to clearly understand the genome homology of 3 species viz. E. intermedia, E. floccifolia and E. tristachya vis-à-vis the A genome of E. indica and to analyze the interspecific relationship among these diploid species and their possible contribution to the evolution of E. coracana. Interspecific F₁ hybrids of E. intermedia×E. indica, E. intermedia×E. floccifolia and E. tristachya×E. intermedia were produced and studied for morphological and cytological details. The experimental data revealed a high degree of homology at the interspecific level among all 4 species resulting in high frequency of bivalents and a very low frequency of univalents and multivalents. Inspite of good chromosome pairing and bivalent formation, a significant reduction in pollen stainability (8–32%) has been recorded in the F₁ hybrids. The data obtained on chromosome associations at diakinesis/ metaphase I of meiosis suggest that these diploid species form a close genetic assemblage within the genus Eleusine. Various factors affecting the pollen stainability and seed fertility are discussed in the light of available information on the subject.