Transcriptome profiling reveals that foliar water uptake occurs with C3 and crassulacean acid metabolism facultative photosynthesis in Tamarix ramosissima under extreme drought

Xia Yan; Yan Chang; Weijia Zhao; Chaoju Qian; Xiaoyue Yin; Xingke Fan; Xinyu Zhu; Xiangqiang Zhao; Xiao-Fei Ma

doi:10.1093/aobpla/plab060

Transcriptome profiling reveals that foliar water uptake occurs with C₃ and crassulacean acid metabolism facultative photosynthesis in Tamarix ramosissima under extreme drought

AoB Plants. 2022 Jan 17;14(1):plab060. doi: 10.1093/aobpla/plab060. eCollection 2022 Feb.

Authors

Xia Yan^{1

2}, Yan Chang¹, Weijia Zhao¹, Chaoju Qian³, Xiaoyue Yin^{3

4}, Xingke Fan^{3

4}, Xinyu Zhu¹, Xiangqiang Zhao¹, Xiao-Fei Ma^{1

3}

Affiliations

¹ School of Life Sciences, Nantong University, Nantong 226019, Jiangsu, China.
² Key Laboratory of Inland River Ecohydrology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China.
³ Key Laboratory of Stress Physiology and Ecology in Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China.
⁴ College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Tamarix ramosissima is a typical desert plant species that is widely distributed in the desert areas of Northwest China. It plays a significant role in sand fixation and soil water conservation. In particular, how it uses water to survive in the desert plays an important role in plant growth and ecosystem function. Previous studies have revealed that T. ramosissima can alleviate drought by absorbing water from its leaves under extreme drought conditions. To date, there is no clear molecular regulation mechanism to explain foliar water uptake (FWU). In the present study, we correlated diurnal meteorological data, sap flow and photosynthetic parameters to determine the physical and biological characteristics of FWU. Our results suggested that the lesser the groundwater, the easier it is for T. ramosissima to absorb water via the leaves. Gene ontology annotation and Kyoto Encyclopaedia of Genes and Genomes pathway analysis of the transcriptome profile of plants subjected to high humidity suggested that FWU was highly correlated to carbohydrate metabolism, energy transfer, pyruvate metabolism, hormone signal transduction and plant-pathogen interaction. Interestingly, as a C₃ plant, genes such as PEPC, PPDK, MDH and RuBP, which are involved in crassulacean acid metabolism (CAM) photosynthesis, were highly upregulated and accompanied by FWU. Therefore, we proposed that in the case of sufficient water supply, C₃ photosynthesis is used in T. ramosissima, whereas in cases of extreme drought, starch is degraded to provide CO₂ for CAM photosynthesis to make full use of the water obtained via FWU and the water that was transported or stored to assimilating branches and stems. This study may provide not only an important theoretical foundation for FWU and conversion from C₃ plants to CAM plants but also for engineering improved photosynthesis in high-yield drought-tolerant plants and mitigation of climate change-driven drought.

Keywords: Carbon assimilation; Tamarix ramosissima; foliar water uptake; gene expression; transcriptome profiling.