Relationship between Lignin Metabolism and Lodging Resistance in Wheat

Abstract

To disclose the relationship between lignin content and lodging resistance, field experiments were conducted in 2012 and 2013 to investigate the dynamic changes of lignin content, the activities of four enzymes involved in lignin metabolism in culm, as well as the snapping resistance and lodging index of buckwheat. The lignin content and activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), cinnamyl alcohol dehydrogenase (CAD), and 4-coumarate: CoA ligase (4CL) were tested with the 2 nd internode of four cultivars with different lodging resistance. The snapping resistance and culm lodging index were determined at anthesis, grain filling, and maturity stages. The lignin content varied significantly among cultivars. The XD cultivar, which showed high resistance to culm snapping and lodging, had higher lignin content and higher activity of PAL, TAL, 4CL, and CAD than other cultivars. The lignin content was significantly negatively correlated with the actual lodging percent ( r = -0.844, P < 0.01) and the lodging index ( r = -0.832, P < 0.05), and was significantly positively correlated with the snapping resistance ( r = 0.873, P < 0.01). The activities of PAL, TAL, 4CL, and CAD were positively correlated with lignin content with correlation coefficients of 0.984 ( P <0.01), 0.619 ( P > 0.05), 0.927 ( P < 0.01), and 0.862 ( P < 0.01), respectively. In conclusion, our results indicate that the activities of PAL and 4CL were the key enzymes that influenced the lignin content, and that the lignin content can be used as main indicators to evaluate the lodging resistance of buckwheat.