Lodging resistance of winter wheat (Triticum aestivum L.): Lignin accumulation and its related enzymes activities due to the application of paclobutrazol or gibberellin acid

• We investigated the effect of PP333 or GA3 on wheat basal second internode characteristics.
• Lignin accumulation exhibited important functions in regulating the breaking strength of internode.
• Application of PP333 or GA3 regulated lodging resistance of wheat by affecting lignin biosynthesis.
• We presented a target for improving the lodging resistance of wheat.

Lodging is an important constraint limiting wheat yields and quality by bending or breaking stems on wheat (Triticum aestivum L.) production worldwide. This study was conducted to determine whether lignin accumulation and lodging resistance of winter wheat could be affected by application of paclobutrazol (PP333) or gibberellin acid (GA3) at stem elongation stage (DC 3.0). Two winter wheat cultivars, Jimai22 (lodging-tolerant cultivar; JM22) and Shannong16 (lodging-susceptible cultivar; SN16), were used to investigate the effect of exogenous hormones on wheat lodging behavior, lignin accumulation in culms and its relation to lodging resistance. Results showed that application of PP333 significantly reduced plant height and the length of basal second internode, while GA3 had the opposite effect. Lignin accumulation was positively and significantly correlated with the breaking strength of internode and culm lodging resistance index (CLRI). PP333 significantly increased lignin accumulation and its related enzymes activities in the basal second internode, and also increased the diameter, wall thickness, filling degree of the internode, thus the breaking strength and lodging resistance of wheat increased. Whereas, GA3 caused opposite effect on those characteristics. These results suggested that the exogenous PP333 or GA3 application significantly changed the risk of lodging occurred not only by altering the plant height but also by altering the physical strength of the basal part of the culm internode, especially, altering the lignin accumulation and its related enzymes activities in basal internode.