TgMYC2-TgPAL module regulated by jasmonic acid mediates the dehiscence of Torreya grandis staminate strobilus

The MYC transcription factor serves as a crucial regulator of plant growth and development. In this study, we identified 10 MYC family members from the genome of T. grandis and conducted a systematic analysis of their evolutionary relationships, conserved domains, and gene structures. Expression pattern analysis revealed that TgMYC2/3/7 exhibited significantly high expression during the dehiscence stage of staminate strobili. Functional studies showed exogenous MeJA promoted staminate strobilus dehiscence and significantly upregulated TgMYC2 and TgMYC3 expression. Consistently, overexpression experiments further confirmed that TgMYC2 was sufficient to promote staminate strobilus dehiscence. Moreover, in OE-TgMYC2 group, the expression level of TgPAL and lignin content were all significantly higher than those in the control group. Further dual-luciferase and yeast one-hybrid assays demonstrated that TgMYC2 could directly bind to the P4 fragment of the TgPAL promoter and activate its transcription. Consistent with this, transient expression assays, physiological experiments, and biochemical assays confirmed that TgPAL enhances lignin biosynthesis, thereby facilitating staminate strobilus dehiscence. In conclusion, these results reveal that TgMYC2 promotes staminate strobilus dehiscence by mediating jasmonic acid and directly regulating TgPAL expression to influence lignin synthesis. This research sheds new light on the molecular mechanisms governing reproductive development in T. grandis, while identifying potential targets to enhance its breeding efficiency.