Does jasmonic acid regulate photosynthesis, clastogenecity, and phytochelatins in Brassica juncea L. in response to Pb-subcellular distribution?

The present experiment unravels how exogenous jasmonic acid regulates photosynthesis, clastogenecity, AsA-GSH cycle and phytochelatins in Brassica juncea L. in response to Pb-subcellular distribution. The plants were evaluated for leaf gas exchange parameters, Fv/Fm, lipid peroxidation, leaf epidermal structures and ABA content. Besides lead accumulation in root, shoot and its subcellular distribution pattern, its role as clastogen and/or aneuploidogen via DNA damage, genome size and ploidy variations, AsA-GSH cycle and quantification of PC2 and PC3 were performed as well. Results revealed that Pb inhibited plant growth, disturbed epidermal and guard cells and consequently worsen leaf gas exchange parameters (E, GH2O, A), Fv/Fm and photosynthetic pigments. For clastogenecity, results revealed considerable DNA damage and analysis for genome size showed that differences between unstressed, Pb-stress and JA application were not significant (P ≤ 0.05), however, ploidy ratio analysis proved partial aneuploidogenic role of Pb. The highest Pb exposure affected AsA-GSH cycle negatively but increased PC2 and PC3 contents uniformly in roots and leaves. Surprisingly, exogenous JA inhibits plant growth under non-stress but positively regulates growth, photosynthesis, AsA-GSH cycle, PC2 and PC3 contents and DNA damage but has no significant effect on variations in total genome size and ploidy under Pb-stress.