Pollen-Pistil Interaction Study in Self-Incompatible and Protogyny Lines of Indian Mustard (Brassica juncea L.)

This study focused on a unique cross-pollinated (self-incompatible) genotype of Indian Mustard for successful seed production and its maintenance. Protogynous (PG) line identified in Indian mustard is found to be self-incompatible (SI) which would be an alternate system to be used as female line in hybrid development. Fluorescence microscopic investigation was made to understand the interaction between developing pistil and pollen of PG-SI, PG, Non-PG and cytoplasmic male sterile (CMS) lines. Intra-specific crosses of (PG-SI) × (PG-SI) did not show single pollen germination on the stigmatic surface and, consequently, no pollen tube growth was observed up to three days after pollination. Stigma of flower in PG-SI plants treated with salts and hormone like NaCl (0.34 M), GA3 (1.45 mM) and Kinetin (2.23 mM) and their interaction showed successful selfing during maintenance of SI Plants. NaCl treatment was found to be more successful in breaking self-incompatibility in PG-SI lines. The entire process of intra-specific PG-SI × non-PG-SI and treated (PG-SI) × (PG-SI) post pollination events, starting from pollen deposition on the surface of the stigma and into the embryo sac, was rapid and completed within two days of pollination. This study establishes seed setting efficiency upon crossing similar to that found in self-compatible plants which is important for successful base line for SI based hybrid development.