Role of exogenous abscisic acid in freezing tolerance of mangrove Kandelia obovata under natural frost condition at near 32oN

Mangrove Kandelia obovata, an important coastal shelterbelt and landscape tree, is distributed in tropical and subtropical shores and likely delimited in the latitudinal range by varying sensitivity to cold. Here, we explored the temporal variations in physiological status and transcriptome profiling of K. obovata under natural frost conditions at ~32oN, as well as the positive role of exogenous abscisic acid (ABA) in cold resistance. Five different concentrations of ABA (0, 5, 25, 50, and 100 mg L-1) were set to treat K. obovata with a hand-held sprayer until run off. Each treatment was set up with three subplots for a total of 9 replicate seedlings.