Effect of naringenin on the growth and lignin biosynthesis of gramineous plants

摘要

Lignin biosynthesis is essential for plant growth. 4-Coumarate CoA ligase (4-CL, EC6.2.1.12) is involved in the monolignol synthesis and occupies a key role in regulating carbon flow into the phenylpropanoid metabolism pathway Naringenin, one of the metabolites in this pathway, is known as a potent in vitro inhibitor of 4-CL. The growth of rice (Otyza sativa L. cv. Koshihikari), maize (Zea mays L. cvYellow corn) and Echinochloa oryzicola Vasing seedlings at the 2nd leaf stage was inhibited after continuous root application with 0.1 mmol L~(-1) naringenin for 1 week, although naringenin did not kill these gramineous plants. The highest inhibition of fresh weight increase was observed in maize, followed by rice and E. oryzicola. The symptoms in theseplants were root browning, delay of leaf/root development and shoot dwarfing. Naringenin treatment increased the contents of 4-CL substrates, cinnamic acid, 4-coumaric acid, caffeic acid and ferulic acid from 1.2 to 7.2 times and from 1.2 to 3.5 times inshoots and roots, respectively, except for ferulic acid in E. oryzicola roots. It also caused a slight decrease of the lignin content and alteration of lignin constitutions in rice plants. These results suggested that the monolignol pathways after 4-CLtowards lignin has the possibility to be the novel action sites of plant growth retardants, although further investigations are needed to clarify the mode of action.