The transcription factor CnERF109 modulates cold tolerance through regulating α-linolenic acid biosynthesis in Qinghai–Tibet Campeiostachys nutans Griseb

Cold stress severely limits plant growth and agricultural productivity. As a polyunsaturated fatty acid (C18:3), α-linolenic acid (α-LeA) enhances plant cold tolerance by modulating membrane fluidity. However, the regulatory mechanisms governing α-LeA accumulation in Qinghai-Tibet Campeiostachys nutans remain unclear. Here, we demonstrate that exogenous α-LeA improves cold tolerance by maintaining redox homeostasis and activating jasmonic acid (JA) biosynthesis. Notably, elevated JA levels feedback-regulated the expression of CnPLA1, encoding phospholipase A1-II 7, which catalyzes membrane phospholipid hydrolysis to synthesize α-LeA. Transgenic rice overexpressing CnPLA1 exhibited higher endogenous α-LeA levels and enhanced cold tolerance via improved antioxidant activity, whereas CnPLA1 silencing in C. nutans reduced cold tolerance and compromised membrane stability. Yeast one-hybrid screening and protein-DNA interaction analyses confirmed that the transcription factor CnERF109 directly binds to the GCC-box motif in the CnPLA1 promoter, activating its transcription. Furthermore, CnERF109 was shown to regulate cold tolerance through CnPLA1-mediated α-LeA synthesis and redox homeostasis. Our findings reveal that the CnERF109-CnPLA1 module plays a pivotal role in α-LeA biosynthesis and cold adaptation in C. nutans, offering novel insights for breeding cold-resistant forage and cereal crops.