Expressional characterization of two class I trehalose-6-phosphate synthase genes in Hevea brasiliensis (para rubber tree) suggests a role in rubber production
In plants, trehalose-6-phosphate (Tre6P) synthesized by the Tre6P synthase (TPS) acts as a signal metabolite in regulating sucrose metabolism in relation to plant growth and development. The Hevea genome predicts a total of 14 TPS genes, and two class I TPS members, HbTPS1 and 2, were explored here for their expressions under various hormone and abiotic stress treatments. HbTPS1 and 2 expressions in latex, cytoplasm of rubber-producing laticifers, were markedly affected by the treatments of ethephon (2-chloroethylphosphonic acid, an ethylene releaser), 2,4-dichlorophenoxyacetic acid, jasmonic acid and salicylic acid although in a distinct manner. HbTPS1 and 2 expressions were significantly up-regulated in a similar manner by cold (5 °C) and heat (40 °C) as examined in Hevea seedling leaves and roots, and by wounding in latex. In comparison, the drought treatment (20% PEG) posed a different effect on HbTPS1 and 2 expressions in Hevea seedlings. For example, in roots, HbTPS1 transcripts accumulated with the treatment, whereas those of HbTPS2 decreased for the first 24 h. Various hormone- and stress-responsive elements could be in silico predicted in HbTPS1 and 2 promoters, and a universal expression was observed for the HbTPS1::GUS activity in all growth stages of transgenic Arabidopsis. These results, coupled with the fact of rubber biosynthesis as a defense response using sucrose as the precursor molecule, propose a potential role of TPS genes in regulating rubber production.
KeywordsHevea brasiliensis Trehalose-6-phosphate synthase Gene expression Hormone Abiotic stress Rubber production
This work was supported by the Natural Science Foundation of China (31570672) and the National High Technology Research and Development Program (863) (2013AA102605).
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