Jasmonates (JAs) are the most effective inducers for the biosynthesis of various secondary metabolites. Currently, jasmonate ZIM domain (JAZ) and its interactors, such as MYC2, constitute the main JA signal transduction cascade, and such a cascade fails to directly regulate all the taxol biosynthesis genes, especially the rate-limit gene, DBAT. Another JA signaling branch, JAV and WRKY, would probably fill the gap. Here, TcJAV3 was the closest VQ-motif-containing protein in Taxus chinensis to AtJAV1. Although TcJAV3 was overexpressed in AtJAV1 knockdown mutant, JAVRi17, the enhanced disease resistance to Botrytis cinerea caused by silencing AtJAV1 was completely recovered. The results indicated that TcJAV3 indeed transduced JA signal as AtJAV1. Subsequently, TcWRKY26 was screened out to physically interact with TcJAV3 by using a yeast two-hybrid system. Furthermore, bimolecular fluorescence complementation and luciferase complementary imaging also confirmed that TcJAV3 and TcWRKY26 could form a protein complex in vivo. Our previous reports showed that transient TcWRKY26 overexpression could remarkably increase DBAT expression. Yeast one-hybrid and luciferase activity assays revealed that TcWRKY26 could directly bind with the w_a-box of the DBAT promoter to activate downstream reporter genes. All of these results indicated that TcWRKY26 acts as a direct regulator of DBAT, and the TcJAV3–TcWRKY26 complex is actually another JA signal transduction mode that effectively regulates taxol biosynthesis in Taxus. Our results revealed that JAV–WRKY complexes directly regulated DBAT gene in response to JA stimuli, providing a novel model for JA-regulated secondary metabolism. Moreover, JAV could also transduce JA signal and function non-redundantly with JAZ during the regulation of secondary metabolisms.

Perennial ryegrass is a widely cultivated cool-season forage and turf grass species whose growth and development are limited by drought and high temperature. MAX2 is an F-box leucine-rich repeat (LRR) protein, which serves as a central component of strigolactone (SL) and karrikin (KAR) signaling pathways, involved in multiple growth and developmental processes as well as stress response. Here, we identified LpMAX2, a perennial ryegrass (Lolium perenne L.) homolog of Arabidopsis MAX2 (AtMAX2) and rice D3. LpMAX2 can interact with AtD14 and LpD14 in an SL-dependent manner, implying functional conservation with AtMAX2. Overexpression of LpMAX2 in the Arabidopsis max2-3 mutant partially rescued leaf morphology, hypocotyl elongation, and branching phenotypes, while fully restoring drought tolerance, highlighting the evolutionarily conserved roles of MAX2 in plant growth and drought resistance. In conclusion, LpMAX2 is evolutionarily conserved in SL/KAR signaling pathways, highlighting its potential function in drought adaptation. In addition to elucidating the biological function of LpMAX2, this study identifies a promising genetic target for enhancing stress resilience in forage grasses through biotechnological approaches.