RlTTG1 isolated from Rosa laevigata Michx. regulates trichome development and stress response in transgenic...

Rosa laevigata Michx. (R. laevigata) is an important horticultural plant with strong drought resistance and ornamental value. Its fruit can be used as medicine, but its fruits and stems are covered with dense prickles, which leads to difficulty for cultivation. The molecular mechanism of prickle development in R. laevigata is still unknown. In the present study, eighty-one prickle-related genes were found by transcriptome sequencing. A gene closely related to prickle development was selected for functional research, which was named TRANSPARENT TESTA GLABRA 1 (TTG1). RlTTG1 (Rl corresponds to R. laevigata) is highly expressed in the prickles rich tissues. Overexpression of RlTTG1 in Arabidopsis (At represents the species of Arabidopsis), a model plant where epidermal protrusions are termed trichomes (unlike the prickles in R. laevigata), caused an increased number of leaf trichomes but reduced root hair growth. When exposed to abiotic stress, the roots of overexpressed RlTTG1 lines grew longer than the wild type. And increased the seed germination rate under drought and salt stress. Physiological and biochemical tests showed that the contents of proline (Pro) and superoxide dismutase (SOD) activity were increased, while the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) were significantly reduced. In addition, Yeast two-hybrid (Y2H) and Bimolecular fluorescence complementation (BiFC) experiments found that RlTTG1 can interact with several trichome-related proteins, including ENHANCER OF TRY AND CPC 1 (RlETC1), ENHANCER OF TRY AND CPC 3 (RlETC3), Glabra 1a (RlGL1a), Glabra 1b (RlGL1b), and ENHANCER OF GLABRA 3 (RlEGL3). Overall, this study lays the foundation for the research on the molecular mechanism of prickle development and stress response in R. laevigata.