Understanding the Mechanism of Salt Tolerance in Pandanus odorifer L.
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Pandanus odorifer L. belongs to Pandanaceae grows in the wild, mainly in semi-natural vegetation throughout the tropical and subtropical Pacific in littoral habitats, where it prevails against drought, strong winds, and salt sprays. To investigate the mechanism of salt stress tolerance in P. odorifer, the leaves from natural populations growing in the coastal region (SW) and those maintained under fresh water conditions (FW) were compared and analyzed for the common osmolytes proline, glycine betaine and γ-aminobutyric acid (GABA). The proline contents in both FW (13 µmol/g) and SW (12.7 µmol/g) plants were found nearly equal. The glycine betaine in FW plants was 0.745 µmol/g and in SW plants, it was 1.71 µmol/g and the amount of GABA in SW plants was ~60 and ~15 µmol/g in FW plants. Thus, among the three metabolites, GABA contents were found significantly higher, hence, the key enzymes responsible for GABA biosynthesis; glutamate decarboxylase (GAD EC 22.214.171.124), succinic semialdehyde dehydrogenase (SSADH EC 126.96.36.199) and betaine aldehyde dehydrogenase 2 (BADH2 EC 188.8.131.52) were studied with respect to their activity and expression levels in FW and SW plants. Relative expression of GAD was higher in both FW as well as in SW plants of P. odorifer. The highest activity and expression level of GAD under both the conditions suggests that probable pathway for GABA synthesis in P. odorifer is via GABA shunt.
KeywordsGABA GABA shunt Glutamate decarboxylase Glycine betaine Pandanus odorifer Proline Salinity
Succinic semialdehyde dehydrogenase
Betaine aldehyde dehydrogenase2
First author thank University Grants Commission (UGC), New Delhi for the award of BSR fellowship. The authors also thank Dr. Trupti Kad and Dr. Rahul Zanan for their help and suggestions.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
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