Systematic hormone-metabolite network provides insights of high salinity
tolerance in Pongamia pinnata (L.) pierre
Abstract
Salinity stress results significant losses in plant productivity, and
loss of cultivable lands. Although Pongamia pinnata is reported
to be a salt tolerant semiarid tree crop, the adaptive mechanisms to
saline environment are elusive. The present investigation describes
alterations in hormonal and metabolic responses in correlation with
physiological and molecular variations in leaves and roots of Pongamia
at sea salinity level (3% NaCl) for 8 days. At physiological level,
salinity induced adjustments in plant morphology, leaf gas exchange and
ion accumulation patterns were observed. Our study also revealed that
phytohormones including JAs and ABA play crucial role in promoting the
salt adaptive strategies such as apoplasmic Na+
sequestration and cell wall lignification in leaves and roots of
Pongamia. Correlation studies demonstrated that hormones including ABA,
JAs and SA showed a positive interaction with selective compatible
metabolites (sugars, polyols and organic acids) to aid in maintaining
osmotic balance and conferring salt tolerance to Pongamia. At the
molecular level, our data showed that differential expression of
transporter genes as well as antioxidant genes regulate the ionic and
ROS homeostasis in Pongamia. Collectively, these results shed new
insights on an integrated physiological, structural, molecular and
metabolic adaptations conferring salinity tolerance to Pongamia.