Soybean under smoke and flooding

Soybean is an important crop with abundant protein, vegetable oil, and several phytochemicals. Meanwhile, plant-derived smoke plays a key role in plant growth. To investigate the effect of plant-derived smoke on the growth of soybean, a gel-free/label-free proteomic technique was used. The length of root including hypocotyl increased in soybean treated with 2000 ppm plant-derived smoke within 4 days. On treatment with plant-derived smoke, ribosome-related proteins increased and proteasome-related proteins decreased in roots including hypocotyl. Because arginase increased and arginosuccinate synthase/glutamine synthase decreased, the relationship between plant-derived smoke and arginine metabolism was confirmed. Metabolites related to amino acids, carboxylic acids, and sugars were mostly altered with the treatment of smoke. Amino acids related to lipid synthesis and protein phosphorylation increased; while those related to arginine metabolism intensively changed in smoke-treated soybean. In addition, nitric oxide significantly increased as well. On the other hand, under flooding stress, plant-derived smoke induced sacrifice-for-survival-mechanism-driven degradation of root tip in soybean, which promoted lateral root development during soybean recovery after flooding. These results suggest that plant-derived smoke improves early stage of growth in soybean with the balance of arginine synthesis/degradation and regulates soybean tolerance towards flooding.