Shade stress decreases stem strength of soybean through restraining lignin biosynthesis
LIU Wei-guo1*, Sajad Hussain1*, LIU Ting1, ZOU Jun-lin2, REN Meng-lu1, ZHOU Tao1, LIU Jiang1, YANG Feng1, YANG Wen-yu1
1 Institute of Ecological Agriculture, Sichuan Agricultural University/Sichuan Engineering Research Center for Crop Strip Intercropping System, Chengdu 611930, P.R.China 2 Rural Development Office of Pengzhou, Chengdu 611930, P.R.China
Lodging is the most important constraint for soybean growth at seedling stage in maize-soybean relay strip intercropping system. In the field experiments, three soybean cultivars Nandou 032-4 (shade susceptible cultivar; B1), Jiuyuehuang (moderately shade tolerant cultivar; B2), and Nandou 12 (shade tolerant cultivar; B3) were used to evaluate the relationship between stem stress and lignin metabolism in the stem of soybean. Results showed that the intercropped soybean was in variable light condition throughout the day time and co-growth stage with maize. The xylem area and cross section ratio played a main role to form the stem stress. The B3 both in intercropping and monocropping expressed a high stem stress with higher xylem area, lignin content, and activity of enzymes (phenylalanine ammonia-lyase (PAL), 4-coumarate: CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD)) than those of B1 and B2. Among the soybean cultivars and planting pattern, lignin content was positively correlated with stem stress. However, a negative correlation was found between lignin content and actual rate of lodging. In conclusion, the shade tolerant soybean cultivar had larger xylem area, higher lignin content and activities of CAD, 4CL, PAL, and POD than other soybean cultivars in intercropping. The lodging in maize-soybean intercropping can be minimized by planting shade tolerant and lodging resistant cultivar of soybean. The lignin content in stem could be a useful indicator for the evaluation of lodging resistance of soybean in intercropping and activities of enzymes were the key factors that influence the lignin biosynthesis.
Fund: This study was carried out with the support of the National Key R&D Program of China (2018YFD1000905, 2016YFD0300209) and the National Natural Science Foundation of China (31671626). The authors also thank Dr. Yu Xiaobo (Nanchong Academy of Agricultural Sciences, Sichuan Province, China) for providing soybean seeds for the research.
Corresponding Authors: Correspondence YANG Wen-yu, Tel: +86-28-86290960, E-mail: firstname.lastname@example.org
* These authors contributed equally to this study.
Cite this article:
LIU Wei-guo, Sajad Hussain, LIU Ting, ZOU Jun-lin, REN Meng-lu, ZHOU Tao, LIU Jiang, YANG Feng, YANG Wen-yu. 2019. Shade stress decreases stem strength of soybean through restraining lignin biosynthesis. Journal of Integrative Agriculture,