The Receptor-Like Kinase <i>ERECTA</i> Confers Improved Water Use Efficiency and Drought Tolerance to Poplar via Modulating Stomatal Density

• Main Authors: Huiguang Li, Yanli Yang, Houling Wang, Sha Liu, Fuli Jia, Yanyan Su, Shuang Li, Fang He, Conghua Feng, Mengxue Niu, Jie Wang, Chao Liu, Weilun Yin, Xinli Xia
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Populus</i>; <i>ERECTA</i>; stomatal density; water use efficiency; drought stress tolerance
• Online Access: https://www.mdpi.com/1422-0067/22/14/7245
• ISSN: 1661-6596; 1422-0067

Poplar is one of the most important tree species in the north temperate zone, but poplar plantations are quite water intensive. We report here that CaMV 35S promoter-driven overexpression of the <i>PdERECTA</i> gene, which is a member of the LRR-RLKs family from <i>Populus nigra</i> × (<i>Populus deltoides</i> × <i>Populus nigra</i>), improves water use efficiency and enhances drought tolerance in triploid white poplar. <i>PdERECTA</i> localizes to the plasma membrane. Overexpression plants showed lower stomatal density and larger stomatal size. The abaxial stomatal density was 24–34% lower and the stomatal size was 12–14% larger in overexpression lines. Reduced stomatal density led to a sharp restriction of transpiration, which was about 18–35% lower than the control line, and instantaneous water use efficiency was around 14–63% higher in overexpression lines under different conditions. These phenotypic changes led to increased drought tolerance. <i>PdERECTA</i> overexpression plants not only survived longer after stopping watering but also performed better when supplied with limited water, as they had better physical and photosynthesis conditions, faster growth rate, and higher biomass accumulation. Taken together, our data suggest that <i>PdERECTA</i> can alter the development pattern of stomata to reduce stomatal density, which then restricts water consumption, conferring enhanced drought tolerance to poplar. This makes <i>PdERECTA</i> trees promising candidates for establishing more water use efficient plantations.