Yuan Hongliang, Qian Jingya, Wang Chunwei, Shi Weixi, Chang Huiling, Yin Haojie, Xiao Yulin, Wang Yue, Li Qiang
Department of Agronomy, College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
The Key Laboratory of Crop Germplasm Innovation and Resource Utilization of Hunan Province, Hunan Agricultural University, Changsha 410128, China.
Int J Mol Sci. 2025 Jan 29;26(3):1171. doi: 10.3390/ijms26031171.
In order to analyze the physiological regulation mechanisms associated with exogenous melatonin on rice blast, this study treated rice seedlings with different concentrations of melatonin (0, 20, 100, and 500 µmol/L) in order to investigate the growth characteristics, root morphology, superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity, malondialdehyde (MDA) content, hydrogen peroxide (HO) content, and soluble protein content of rice seedlings. The results indicated that 100 µmol/L of melatonin exhibited a significant effect, improving the growth and antioxidant capacity of rice seedlings under rice blast fungus infection. The disease resistance level of rice seedlings against rice blast significantly decreased by 31.58% when compared to the 0 µmol/L melatonin treatment, while the plant height, stem base width, plant leaf area, total root length, aboveground dry weight, aboveground fresh weight, and underground fresh weight significantly increased by 8.72% to 91.38%. Treatment with 100 µmol/L of melatonin significantly increased catalase activities and soluble protein content, with respective increases of 94.99% and 31.14%. Simultaneously, the contents of malondialdehyde and hydrogen peroxide significantly decreased, reaching 18.65% and 38.87%, respectively. The gray relational grade analysis indicated that hydrogen peroxide content and resistance level exhibit the highest gray relational grades with melatonin concentration and, so, can be used to evaluate the effect of melatonin on the severity of rice blast fungus infection. Furthermore, the membership function analysis revealed that the 100 µmol/L melatonin treatment had the highest membership function value, indicating a significant improvement in the resistance of rice seedlings to rice blast disease. In conclusion, 100 µmol/L of melatonin enhances the resistance of rice seedlings to rice blast disease through promoting their growth and strengthening their antioxidant defenses. This study provides new insights into the tolerance mechanisms of rice seedlings against rice blast disease.
为了分析外源褪黑素与稻瘟病相关的生理调节机制，本研究用不同浓度的褪黑素（0、20、100和500 μmol/L）处理水稻幼苗，以研究水稻幼苗的生长特性、根系形态、超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性、过氧化氢酶（CAT）活性、丙二醛（MDA）含量、过氧化氢（HO）含量和可溶性蛋白含量。结果表明，100 μmol/L的褪黑素表现出显著效果，提高了稻瘟病菌感染下水稻幼苗的生长和抗氧化能力。与0 μmol/L褪黑素处理相比，水稻幼苗对稻瘟病的抗病水平显著降低了31.58%，而株高、茎基部宽度、植株叶面积、总根长、地上部干重、地上部鲜重和地下部鲜重显著增加了8.72%至91.38%。用100 μmol/L的褪黑素处理显著提高了过氧化氢酶活性和可溶性蛋白含量，分别增加了94.99%和31.14%。同时，丙二醛和过氧化氢含量显著降低，分别达到18.65%和38.87%。灰色关联度分析表明，过氧化氢含量和抗病水平与褪黑素浓度的灰色关联度最高，因此可用于评价褪黑素对稻瘟病菌感染严重程度的影响。此外，隶属函数分析表明，100 μmol/L褪黑素处理的隶属函数值最高，表明水稻幼苗对稻瘟病的抗性有显著提高。总之，100 μmol/L的褪黑素通过促进水稻幼苗生长和增强其抗氧化防御能力来提高其对稻瘟病抗性。本研究为水稻幼苗对稻瘟病的耐受机制提供了新的见解。
