The Phenylpropanoid Gatekeeper CtPAL1 Coordinates ABA-Induced Flavonoid Biosynthesis and Oxidative Stress Tolerance in Safflower (Carthamus tinctorius L.)

作者：Xiaoyu Liu, Xiaoyu Liu, G.H. Zhang, Mingran Dai, Hong Zhao, Wei Ma, Yanli Hu, Na Yao, Jian Zhang, Naveed Ahmad, Xiuming Liu, Xiuming Liu · 发表于：Plants · 年份：2025 · DOI：10.3390/plants14233606 · 被引用次数：7 · 研究领域：Plant Gene Expression Analysis、Insect-Plant Interactions and Control、Plant Stress Responses and Tolerance

Phenylalanine ammonia-lyase (PAL) catalyzes the first committed step in the phenylpropanoid pathway that governs the entry of carbon flux into flavonoid biosynthesis and stress-responsive metabolism. However, how PAL explicitly mediates hormonal-induced flavonoid biosynthesis and promotes the antioxidant defense system in safflower (Carthamus tinctorius L.) remains largely unknown. Here, we functionally characterize CtPAL1 and demonstrated its regulatory role in abscisic acid (ABA)-induced flavonoid biosynthesis and antioxidant defense. Using phylogenetic and structural predictions, we found that CtPAL1 was placed within a conserved branch of Asteraceae PAL proteins. A promoter analysis indicated multiple hormone- and stress-responsive cis-elements, and exposure to abiotic and hormonal treatments elicited complex, stimulus-dependent dynamics of CtPAL1 expression and flavonoid accumulation. Upon ABA treatment, the expression of CtPAL1 is rapidly induced, triggering early flavonoid biosynthesis. Moreover, CtPAL1-overexpressing Arabidopsis lines exhibited enhanced tolerance to ABA-induced stress by lower lipid peroxidation and higher antioxidant enzyme activities, accompanied with increased flavonoid production. Importantly, the transgenic overexpression of CtPAL1 in Arabidopsis led to the upregulation of the upstream flavonoid pathway genes (At4CL, AtCHI) and elevated total flavonoid levels (1.07–1.27-fold versus wild type), while silencing in safflower caused a reduced flavono...