Effect of drought stress on sugar metabolism in leaves and roots of soybean seedlings

• Published in: Plant physiology and biochemistry Vol. 146; pp. 1 - 12
• Main Authors: Du, Yanli, Zhao, Qiang, Chen, Liru, Yao, Xingdong, Zhang, Wei, Zhang, Bo, Xie, Futi
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01-01-2020
• Subjects: Carbohydrate Metabolism; Drought; Droughts; Glycine max; Plant Leaves; Plant Roots; Root to shoot ratio; Seedlings; Stress, Physiological; Sucrose; Sucrose metabolism; Sucrose transporter; Sucrose metabolism; Sucrose transporter; Root to shoot ratio; Sucrose; Drought; Glycine max
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2019.11.003

Sucrose is the main photosynthetic product in plants, and acts as a major energy substrate and signaling regulator of plant growth. Furthermore, sucrose is involved in the responses to various abiotic stresses. However, the role of sucrose in soybean (Glycine max L.) growth and development under drought stress remains largely unknown. In this study, the two soybean cultivars, Shennong8 (CV.SN8) and Shennong12 (CV.SN12), were grown in pot culture and subjected to three water treatments for 15 days: soil moisture contents of 75 ± 5% (CK), 45 ± 5% (MD), and 30 ± 5% (SD) of field capacity. Under drought stress, the reduction in shoot biomass was more pronounced than the reduction of biomass in the root of both soybean cultivars, resulting in higher root/shoot (R/S) ratio. Drought stress increased the contents of soluble sugar and sucrose in the leaves, but decreased starch content; in the roots, all of these parameters were increased. This may be related to the enhanced carbohydrate metabolism activity under drought stress, including notable changes in the activities of sugar metabolism enzymes and expression levels of GmSPS, GmSuSy, GmC-INV, GmA-INV, GmAMY3, and GmBAM1. Furthermore, the expression levels of sucrose transporter genes (GmSUC2, GmSWEET6, and GmSWEET15) in leaves and roots of soybean seedlings were up-regulated under drought stress. In conclusion, our results highlight that the increase in R/S ratio caused by the changes of sugar allocation, metabolism, and transport under drought stress contributes towards drought resistance of soybean.
•Drought stress caused stronger growth inhibition in seedling shoots than in roots.•Drought stress affected sugar allocation, metabolism, and transport.•Soybean root sugar content increased in response to drought stress.