Investigation on the pyhsiological and molecular mechanisms for lavender’s adaptation to long-term salt stress

• Lavender exhibits higher salt tolerance at NaCl concentrations of 100 mM and 200 mM. • AP2/ERF, AUX/IAA, bZIP, and TCP transcription factors enhance plant’s salt tolerance. • Key genes improve lavender's adaptation to salt stress by regulating physiology. Soil salinity, as a major abiotic stress, significantly affects global agriculture. The physiological and molecular mechanisms governing plants water allocation, osmotic adjustment, and antioxidant pathways are crucial to clarifying salt tolerance of plants. Lavender, a valuable aromatic plant, is adversely impacted by soil salinization effecting both growth and physiological processes, but information on the molecular mechanisms underlying its adaptation to salt stress remains limited. In present study, lavender was subjected to 0, 100, 200, and 300 mM NaCl for 28 days to investigate the salt tolerance mechanisms. The results showed that lavender exhibited the stronger salt resistance at 100 and 200 mM NaCl compared to its response at 300mM under long-term stress conditions, based on analysis of membership functions for physiological indexes. Using WGCNA, we identified 37 key DEGs regulating physiological characteristics under prolonged NaCl stress, with a focus on the top 4 modules. In these modules, positive regulation genes LaERF14 and LaPSB6 belonged to AP2/ERF and AUX-IAA TF families, respectively. The negative regulation gene LaCPRF2 and LaTCP7/14 belonged to the bZIP and TCP TF families, respectively. These genes had signature domains, helping plants resist salt stress by adjusting water allocation, synthesizing osmoregulatory substances, and enhancing the antioxidant enzymes activity to alleviate salt stress. These findings may guide scientific efforts to address salt stress in lavender production and enhance the development of salt-tolerant plants.