Co-regulation role of endogenous hormones and transcriptomics profiling under cold stress in Tetrastigma hemsleyanum

Abstract Background: Tetrastigma hemsleyanum Diels et Gilg is a valuable medicinally herb, Chilling sensitivity is the dominant environmental factor limiting the artificial domestication of the plants. Hormone-related gene regulation and hormone signaling pathways in response to cold stress in T. hemsleyanum remain unknown.Results: Some key genes involved in hormones biosynthesis, such as ZEP and NCED genes of ABA biosynthesis, GA2ox, GA3ox, and GA20ox genes of GA biosynthesis, ACO genes of ET biosynthesis were screened to be crucial in cold response. Consistently, the response of ABA and ABA/GA1+3 to cold stress was prior to that of GA1+3, ZR, ABA/IAA, and ABA/ZR. The increasing changes in ABA/GA1+3 turned to a steep decline with the extension of stress time, which might be one factor contributing to cold-sensitivity of T. hemsleyanum under prolonged stress. The cold tolerance of T. hemsleyanum would be enhanced by endogenous ABA but repressed by GA3 when each phytohormone was applied alone. The ABA-mediated promotion and GA-mediated repression of cold tolerance could both be attenuated by the co-application of the two phytohormones within 6h. When the biosynthesis of endogenous ABA and GA were inhibited by FLU and PAC, respectively, the effects of GA and ABA treatment were reversed partially.Conclusions: In summary, we present the first study of global expression patterns of hormone-regulated transcripts in T. hemsleyanum. This study suggested that GA and ABA work antagonistically to balance the responses to cold in T. hemsleyanum. PAC, a GA biogenesis inhibitor, as well as exogenous ABA, might be potential plant growth regulators that can promote cold tolerance of T. hemsleyanum. The study also provided valuable hints in revealing a new theoretical basis and potential candidate genes that govern cold tolerance of T. hemsleyanum.