Recently, Journal of Experimental Botany published online a research paper entitled "Leaf hydraulic vulnerability triggers the decline in stomatal and mesophyll conductance during drought in rice (Oryza sativa)" led by Prof. Shaobing Peng. This study revealed that the reduction of leaf hydraulic conductance led to the rapid response of rice photosynthesis to drought stress.
Drought stress severely affects plant growth and crop yields. Under arid conditions, the rapid closure of stomata has been extensively studied and is considered to be the first step in the plant's response to drought. There are two main hypotheses about the mechanism of drought-induced stomatal closure: hypothesis of ABA accumulation induced by changes in cell volume and leaf turgor pressure reduction. These hypotheses are mainly based on atmospheric drought (air VPD changes) data. Dr. Dongliang Xiong et al. from rice cultivation physiology team used rice as a research material to track carbon assimilation, leaf hydraulic characteristics, and bulge pressure on the dynamic response and adapted characteristics of soil rapid drought and long-term drought. The results showed that the decrease extent of rice assimilation ability mainly depends on the degree of stomata and mesophyll decreasing the carbon dioxide transmission conductance at the initial stage of drought, while the function of Rubisco enzyme and the function of electron transport complex are only inhibited under severe drought conditions. The stomatal closure caused by the drought and the decline of the carbon dioxide transmission conductance caused by the mesophyll were first triggered by the decrease of the hydraulic conductivity, and then the stress hormone accumulation such as ABA was mainly responsible for maintaining the lower stomatal and leaf conductance. The results suggested that the reduction of leaf hydraulic conductance triggers stomatal closure, resulting in the inhibition of photosynthesis, will help people further understand the mechanisms of plant carbon assimilation in response to drought and other adversities, and provide guidance for the future improvement of crop resistance.
The graduate students Xiaoxiao Wang and Tingting Du of Grade 2017 are the co-first authors. Dr. Dongliang Xiong is the author of the correspondence. This work was partly supported by the National Key Program of R&D of China (No. 2016YFD0300210), the Program for Changjiang Scholars and Innovative Research Team in University of China (IRT1247).