Track 4-1-4: Biotechnological Approaches to Improve Range, Pasture and Forage Species
Description
Apomixis is an asexual method of reproduction through seeds. The potential of apomixis has been envisaged as “asexual revolution” by virtue of its capacity to fix hybrid vigour, a much desirable feature in breeding of agricultural crops. The genetic mechanism of apomixis regulation is complex and is believed to be largely affected by polyploidy (Nogler 1984). Expression of apomixis essentially contains three components, viz. apomeiosis (formation of unreduced egg cell), parthenogenesis (fertilization independent embryo development) and functional endosperm development (autonomous or psuedogamous). In contrast to previous reports, the evidence has now gathered that these three components can be functionally uncoupled and recombination is possible between these components (Kaushal, et al., 2008). Such recombinations lead to diversity in seed development pathways and also provide a mechanism to modify the ploidy levels. Uncoupling of apomeiosis from parthenogenesis may yield high frequency of triploids and haploids. Utilizing this partitioning principle we have generated a ploidy series following a Hybridization–supplemented Apomixis-components Partitioning Approach (HAPA) in guinea grass, a model crop for polyploidy and apomixis research, (Kaushal et al., 2009). From a single 4x (2n=32) progenitor, a ploidy series has been developed represented by 3x, 4x, 5x, 6x, 7x, 8x, 9x and 11x cytotypes. This ploidy series offers advantage of studying ploidy regulated gene expression. There have been sporadic reports on effect of polyploidy in expression of apomixis per se; however information on effect of polyploidy on individual apomixis components is not available. The guinea grass ploidy series with sequentially added monoploid genome doses has been used in present study to understand the effect of ploidy levels on phenotypic expression of partitioned apomixis components.
Included in
Ploidy Dependent Expression of Apomixis Components in Guinea Grass (Panicum maximum Jacq.)
Apomixis is an asexual method of reproduction through seeds. The potential of apomixis has been envisaged as “asexual revolution” by virtue of its capacity to fix hybrid vigour, a much desirable feature in breeding of agricultural crops. The genetic mechanism of apomixis regulation is complex and is believed to be largely affected by polyploidy (Nogler 1984). Expression of apomixis essentially contains three components, viz. apomeiosis (formation of unreduced egg cell), parthenogenesis (fertilization independent embryo development) and functional endosperm development (autonomous or psuedogamous). In contrast to previous reports, the evidence has now gathered that these three components can be functionally uncoupled and recombination is possible between these components (Kaushal, et al., 2008). Such recombinations lead to diversity in seed development pathways and also provide a mechanism to modify the ploidy levels. Uncoupling of apomeiosis from parthenogenesis may yield high frequency of triploids and haploids. Utilizing this partitioning principle we have generated a ploidy series following a Hybridization–supplemented Apomixis-components Partitioning Approach (HAPA) in guinea grass, a model crop for polyploidy and apomixis research, (Kaushal et al., 2009). From a single 4x (2n=32) progenitor, a ploidy series has been developed represented by 3x, 4x, 5x, 6x, 7x, 8x, 9x and 11x cytotypes. This ploidy series offers advantage of studying ploidy regulated gene expression. There have been sporadic reports on effect of polyploidy in expression of apomixis per se; however information on effect of polyploidy on individual apomixis components is not available. The guinea grass ploidy series with sequentially added monoploid genome doses has been used in present study to understand the effect of ploidy levels on phenotypic expression of partitioned apomixis components.
