Melatonin (N-acetyl-5-methoxytryptamine) is a well-known animal hormone that plays a broad spectrum of biological functions, such as circadian rhythms, immunomodulation, tumor inhibition, and anti-aging etc. It is also suggested as an antiaging agent. Therefore, in the past 50 years, melatonin received tremendous attention because of its beneficial actions. Recent research revealed that melatonin exists in a wide range of vascular plants, and plays a role in delaying leaf senescence and enhancing abiotic stress resistance. However, the underlying molecular mechanism remains unclear.
A team led by Prof. CHU Chengcai of the State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology (IGDB), recently revealed the molecular mechanism of delaying leaf senescence mediated by melatonin in rice. The work was recently released in J Pineal Res. (DOI:10.1111/jpi.12243).
CHU and his colleagues demonstrated that melatonin acts as a potent agent to delay leaf senescence in rice. Treatments with melatonin significantly reduced chlorophyll degradation, suppressed the transcripts of senescence-associated genes, delayed the leaf senescence, and also enhanced salt stress tolerance. Further analysis revealed that melatonin is a potent free radical scavenger, and exogenous application could result in enhanced antioxidant protection.
Their results demonstrated that melatonin delays the leaf senescence and cell death, and also enhances abiotic stress tolerance via directly or indirectly counteracting the cellular accumulation of H2O2.
"The elucidating of the molecular mechanisms mediated by melatonin in plant will deepen our understanding to the regulation network underlying leaf senescence”. Said Dr. LIANG Chengzhen, the first author of the paper, “the delay senescence of melatonin could have potential application in economically important crops, vegetables, and flowers”.
This work was supported by grants from the Ministry of Agriculture, the National Natural Science Foundation of China, and Zhejiang Provincial Natural Science Foundation of China.
References
Liang C, Zheng G, Li W, Wang Y, Hu B, Wang H, Qian Y, Zhu XG, Tan DX, Chen SY, Chu C (2015)
Melatonin Delays Leaf Senescence and Enhances Salt Stress Tolerance in Rice.
J Pineal Res. DOI:10.1111/jpi.12243.
Contact:
Dr. CHU Chengcai
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences,
Add: No. 1 West Beichen Road, Chaoyang District, Beijing 100101, China.
E-mail:
ccchu@genetics.ac.cn 
Figure. A proposed model of melatonin-mediated delay of leaf senescence and cell death in rice. (Image by IGDB)
