Physiological and molecular mechanisms by which coumarin reduces copper stress in Citrus sinensis roots revealed by physiology, transcriptome, and metabolome

The study validated the hypothesis that COU-mediated alleviation of Cu toxicity in citrus roots was caused by the combination of following several aspects such as: (a) reduced impairment to cell division, endoreduplication, cell differentiation, and cell expansion in roots, as well as subsequent effects on root growth and RSA; (b) enhanced ability to maintain Cu and Ca homeostasis, as well as CW and plasma membrane stability and function, (c) elevated adaptability of carbohydrate, energy, and AA metabolisms to Cu excess and reduced impairment of Cu excess to them in roots; and (d) upregulated biosynthesis and catabolism (turnover) of SMs and reduced alterations of SM abundances.