Executive Summary : | Rationale: Pollen development in flowering plants is a complex phenomenon. It requires the coordination of almost all major plant hormone signalling. The spatiotemporal expression of hormone induced key signalling factors regulate the pollen maturation, anther dehiscence, release of pollen to the surface of stigma and pollen tube germination, for a successful pollination. Defect in any of these development stages can cause loss of fertility or complete sterility. Studies have shown that plant hormone jasmonic acid plays a crucial role in stamen and male gametophyte maturation. Transcription factors that are involved in jasmonate pathways not only coordinate jasmonate signalling but also regulates jasmonic acid biosynthesis pathway through positive and negative feedback mechanism. This coordination is important as optimal amount of jasmonic acid and adequate amplitude of JA signal is needed for the proper growth and development of the plant. Objective: As a part of our previous SERB grant, we have investigated the role of plant specific HMG-box protein AtHMGB15 in pollen development. Our result indicated that athmgb15 mutant plants have defect pollen morphology and retarded pollen tube germination. Comparative transcriptomic study to decipher the role of AtHMGB15 in pollen development shows repression of JA biosynthesis and signalling in athmgb15 flowers. Further, preliminary analysis shows that AtHMGB15 acts as an transcriptional activator for the expression of two important master regulators of JA signalling, MYB21 and MYB24. MYBs are known to be the positive regulator of JA signalling for stamen and pollen development. However, JA signalling needs to be attenuated by regulating the transcriptional activity of MYBs. It is believed that additional stamen -specific factors plays an important role in regulating MYBs activity. Thus, it is important to characterize different components for transcriptional activation of MYBs during pollen development. |