Growth response modulation by putrescine in Indian mustard Brassica juncea L. under multiple stress

Plants, in general, are put to various kinds of stress, biotic and abiotic, both natural and manmade. Infestation by insect pests and diseases, and extreme conditions such as salinity, temperature, etc., as well as heavy metal contamination affect their growth performance. Here, we studied the impact of salinity and heavy metal pollution on the growth performance of Indian Mustard Brassica juncea L. and its amelioration by the diamine, putrescine, a known media supplement. We evaluated the putrescine (Put) modulation potential on multiple stress effect in 7-day old Indian mustard. The germination, seedlings length and photosynthetic pigments decline under salinity and metal (Cd/Pb) stress condition, alone or in combination, were checked by putrescine. The stress induced increase in root-shoot ratio, RNA and total amino acids content, as well as Na⁺/K⁺ ratio in leaf tissues were also comparatively less. The increased endogenous Cd/Pb accumulation in plants exposed to either metal further elevated under salinity was also found decelerated. However, the multiple stressed seedlings showed increase in glutathione content, which was further elevated with putrescine application. The increase in protein contents in leaf under single or combined stresses in the presence of putrescine could be a qualitative change. The differential changes in parameters examined here resulted in improved growth (> 10%) suggests stress mitigation by the putrescine up to an extent.