Occurrence of Apomixis in Eleusine coracana

Abstract

Eighteen different accessions of Eleusine coracana were subjected to detailed morphological analysis of female reproductive parts along with the phasic embryological analysis of the pathways for the formation of female gametophyte for evaluating the reproductive diversity and strategy. In this investigation all the accession possessed Polygonum type of sexual embryo sac. But a few accessions were also showing the formation of Panicum type of aposporic embryo sacs in addition to sexual embryo sac, signifying the presence of facultative apomixis. The aposporic embryo sac initials for the formation of Panicum type of embryo sac differentiated in nucellus. The aposporic embryo sac initial enlarged greatly. Vacuolization soon started because of which the young embryo sac took up unipolar organization with a prominent nucleus at one pole. This nucleus divided mitotically into two which subsequently divided to produce four nuclei, occupying only one pole of the embryo sac. The four nuclei organized into a Panicum type embryo sac having an egg, two synergids and a polar nucleus. Apomixis is an asexual method of propagation through seed in which both meiosis and fertilization are bypassed for the development of an embryo. It is a fascinating method to produce large genetically uniform populations of crop species in which heterozygosity and hybrid vigour can be maintained in successive seed generations.