Detection of facultative apomixis in little millet, Panicum sumatrense

In the present investigation, tetraploid small millet P. sumatrense was explored for detailed morphological and embryological analyses of female reproductive structures to find out apomixis. Twenty six accessions of little millet were taken for this study. All the accessions showed sexual embryo sacs of Polygonum type during the course of sexual reproduction. But out of these twenty six accessions, twelve accessions also showed aposporous embryo sacs of Panicum type besides the formation of sexual embryo sac, indicating the occurrence of facultative apomixis. Development of a 4 nucleated Panicum type embryo sac started with the formation of a large vacuole in an aposporous initial having a nucleus at one pole. After two successive mitotic divisions, 4 nuclei organized into one egg cell with two synergids and one polar nucleus to form a Panicum-type embryo sac. These observations indicated the presence of facultative apomixis within P. sumatrense, as both sexual and apomictic reproductive pathways are functional. This fascinating phenomenon of seed production utilizes the organ involved in sexual seed production, however, surpasses essential steps such as meiosis and syngamy. The detection of apomicts in natural populations provides a broad field of research to learn how apomictic crops cope with biotic and abiotic stresses. The findings of the present investigation can be utilized in complex breeding strategies to generate high-yielding nutritionally enriched resistant varieties.