Response of exogenous melatonin on transcription and metabolism of soybean under drought stress

Abstract

Amino acid metabolism is an important factor in regulating nitrogen source assimilation and source/sink transport in soybean. Melatonin can improve plant stress resistance, but whether it affects amino acid metabolism is not known. Therefore, this study investigated whether exogenous melatonin had an effect on amino acid metabolism of soybean under drought conditions and explored its relationship with yield. The treatments were normal water supply treatment (WW), drought stress treatment (D), drought stress and melatonin treatment group (D + M), sprayed with 100 μmol/L melatonin. The effects of melatonin on amino acid metabolism and grain filling were studied by physiological and omics experiments using Kangxian 9 (drought‐sensitive variety) and Suinong 26 (drought‐resistant variety) soybean cultivars. The results showed that drought stress decreased the activity of carbon and nitrogen metabolizing enzymes, which inhibited the accumulation of dry matter and protein, and decreased the yield. In the drought‐sensitive soybean variety, glycoenzymes and amino acid synthetases synthetic genes were upregulated in melatonin‐treated soybeans, hence carbon and nitrogen metabolism enzyme activity increased, increasing the carbohydrate and amino acid contents simultaneously. This resulted in higher dry matter and yield than drought‐stressed soybean not treated with melatonin. In the drought‐resistant variety, the grain weight per plant increased by 7.98% and 6.57% in 2020 and 2021, respectively, while it increased by 23.20% and 14.07% in the drought‐sensitive variety during the respective years. In conclusion, melatonin treatment can enhance the activity of nitrogen and carbon metabolism and amino acid content by upregulating the expression of soybean metabolic pathway and related genes, thus increasing the yield of soybean under drought stress.

Slight drought during flowering period can improve Tartary buckwheat yield by regulating carbon and nitrogen metabolism

“…Glutamate synthase (GOGAT), nitrate reductase (NR), and glutamate dehydrogenase (GDH) are key enzymes in crop nitrogen metabolism that help crops cope with drought stress; their activities fully reflect the level of nitrogen assimilation in the crop 6 – 8 . Cao et al 9 found that the activity of NR was inhibited under drought stress. Xu et al 10 reported that drought stress reduces NR and GS activity in soybean leaves, and the GOGAT activity shows a trend of initially increasing and then decreasing.…”

Melatonin Mitigates Water Deficit Stress in Cenchrus alopecuroides (L.) Thunb through Up-Regulating Gene Expression Related to the Photosynthetic Rate, Flavonoid Synthesis, and the Assimilatory Sulfate Reduction Pathway

“…Melatonin (chemical name: N-acetyl-5-methoxytryptamine, MT, or Mel) is a versatile small molecule compound belonging to the indole heterocyclic group [ 9 ]. Numerous studies have demonstrated that melatonin is involved in various physiological processes, including alleviating the inhibition of photosynthesis, promoting seed germination, regulating plant growth and root morphology [ 10 , 11 , 12 , 13 , 14 ], and regulating primary and secondary metabolism [ 15 , 16 ]. Under water deficit conditions, exogenous melatonin increased the expression of important genes such as superoxide dismutase (SOD), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) in hickory ( Carya cathayensis ) [ 16 ].…”