ß Pore-forming Protein-based Evolutionary Divergence of Gnathostomata from Agnatha.

INTRODUCTION: The first vertebrates were jawless fish, or Agnatha, whose evolution diverged into jawed fish, or Gnathostomes, around 550 million years ago. METHODS: In this study, we investigated ß PFT proteins' evolutionary divergence of lamprey immune protein from Agnatha, reportedly possessing anti-cancer activity, into Dln1 protein from Gnathostomes. Both proteins showed structural and functional divergence, and shared evolutionary origin. Primary, secondary and tertiary sequences were compared to discover functional domains and conserved motifs in order to study the evolution of these two proteins. The structural and functional information relevant to evolutionary divergence was revealed using hydrophobic cluster analysis. RESULTS: The findings demonstrate that two membrane proteins with only a small degree of sequence identity can have remarkably similar hydropathy profiles, pointing towards conserved and similar global structures. When facing the lipid bilayer or lining the pore lumen, the two proteins' aerolysin domains' corresponding residues displayed a similar and largely conserved pattern. Aerolysin-like proteins from different species can be identified using a fingerprint created by PIPSA analysis of the pore-forming protein. CONCLUSION: We were able to fully understand the mechanism of action during pore formation through structural studies of these proteins.

Stomatal behaviour and endogenous phytohormones promotes intrinsic water use efficiency differently in cotton under drought

The coordination between phytohormones regulation, stomatal behaviour (stomatal index and opening/closing) and gas exchange are potent determinants of plant survival under drought stress. However, we found a knowledge gap in the mechanism regulating the fine-tuning of these features during drought. In order to address this we evaluated gas exchange, stomatal behaviour and endogenous phytohormones content in two cotton varieties (LRA-5166 and NBRI-67) differing in drought sensitivity during water deficit conditions. Variety specific differences were recorded in net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (gs) with significantly less decrease in drought tolerant LRA-5166 than drought sensitive NBRI-67. The abscisic acid (ABA) accumulation was significantly increased in LRA-5166 while reduced in NBRI-67 under water deficit, which was accompanied by relatively less reduced 6-benzylaminopurine (6-BAP) level in LRA-5166 than NBRI-67.Thus, improved ABA/6-BAP ratio was observed in both the varieties of cotton. Critically, LRA- 5166 has reduced stomatal index, aperture size and significantly higher A and intrinsic water use efficiency (WUEi), thus higher drought tolerance than NBRI-67. Furthermore, we found that endogenous ABA predominantly maintains the stomatal behaviour and regulates its physiology either by antagonizing 6-BAP or alone to coordinate with water deficit signals. Overall, our findings describe a new insight as to how drought modulates endogenous ABA and 6-BAP homeostasis in cotton leaf and the mechanism of stomatal regulation by ABA and 6-BAP in cotton.