NAD(β-nicotinamide adenine dinucleotide) as an electron transfer carrier (coenzyme) participates in many redox reactions and is well known by many researchers. In the Preiss handler pathway, nicotinic acid (NA) and a variety of Na derivatives (glycosylation, methylation, etc.) are specific for NAD remediation synthesis in plants, but up to now, the molecular mechanism and physiological function of NA derivatives in plant metabolism have not been reported.
Previous studies by Wang Guodong research group, Institute of genetics and developmental biology, Chinese Academy of Sciences showed that the O-glycosylation modification of Na might protect plant cells from the toxicity caused by excessive accumulation of Na during seed germination, and the activity of NAOGT was gradually obtained during the evolution of Cruciferae Plants, and the acquisition of NAOGT activity provided selection advantages for plants to adapt to the environment (Li et al., plant Cell，2015）。 Recently, Wang Guodong's team found that in Arabidopsis, a new type of N-methyltransferase (NANMT, At3g53140 code) is responsible for the formation of nicotinic acid N-methylated compounds (also known as cucurbitacin). Meanwhile, N-methylated nicotinic acid modification is another form of plant detoxification NA. The results of comprehensive evolutionary and biochemical analysis show that the function of this novel nicotinic acid N-methyltransferase comes from the replication and functional differentiation of COMT (caffeic acid O-methyltransferase) gene, which is involved in the biosynthesis of plant lignin. The original COMT of plants also retains weak NANMT activity, which indicates that the acquisition of NANMT activity contributes to the Preiss handler pathway's retention in terrestrial plant genome during the long evolution of plants.
The research results were published online in Plant Physiology (DOI: 10.1104 / pp.17.00259) on May 22. Li Wei, Zhang Fengxia and Wu Ranran of Wang Guodong research group are the co authors of this paper. The project was supported by NSFC, "973" project of Ministry of science and technology and State Key Laboratory of plant genomics. (From Institute of genetic and developmental biology, Chinese academy of sciences, compiled by www.hsppharma.com)