New Channel Enhances Plant Carbon and Water Use Efficiency

New Channel Enhances Plant Carbon and Water Use Efficiency

It has not always been possible to promote photosynthesis carbon assimilation and increase plant water use efficiency (WUE) at the same time. Recently, researchers at the University of Glasgow in the United Kingdom found that enhance stomatal dynamics can improve WUE without affecting plant carbon fixation. Related research results have been published in the journal Science.   Plant leaf stomata have a dual and mutually contradictory effect, which promotes the inflow of carbon dioxide into the leaves for photosynthesis and limits the efflux of water through transpiration. This means that the pores absorb CO2 and also lose some of the water by transpiration.   Most of the previous studies will focus on improving WUE efforts to reduce stomatal density. “The stomatal density responds to changes in atmospheric CO2 concentration, light, atmospheric relative humidity, and abscisic acid. The situation is complicated, and reducing stomatal density is not an easy task.” Wang Yizhou, a researcher at the School of Agriculture and Biotechnology of Zhejiang University, one of the authors of the paper, said, “In addition, this approach will significantly reduce plant photosynthesis efficiency."   In 2015, Anna Moroni, a professor at the University of Milan in Italy, developed the blue-induced K+ channel 1 (BLINK1) and activated the K+ channel in the zebrafish. “This may be applied to plants to achieve the regulation of plant stomata.” The author of the paper, Michael Glath, professor of the University of Glasgow, told that he has been working for more than 30 years on ion transport and quantitative modeling of stomatal guard cells, and are very interested in developing strategies to improve crop water use through stomatal function.   The researchers expressed the synthetic light-gated K+ channel BLINK1 in guard cells in the stomatal pores of Arabidopsis thaliana as a tool to regulate K+ conductance and accelerate photopore pore size changes in plant guard cells, the solute flux of the driven pore diameter is enhanced to accelerate the opening of the pores under illumination and the closure after irradiation.   According to Blatt, the study attempts to speed up the opening/closing of the pores by accelerating the change in light intensity: when the light intensity rises, the pores open faster and increase the amount of CO2 entering the plant; when the light intensity decreases, the pores close faster and reduce the moisture loss. By focusing on the dynamics of stomatal movement, the effects of CO2 increase and water loss are effectively separated.   To verify whether BLINK1 in guard cells performs this function, the researchers examined BLINK1 transgenic lines grown during daylight and found no significant differences in biomass accumulation, garland area expansion or water use compared to normal plants.   Then, the researchers have observed the plants in fluctuating light. Studies have found that as the cloud passes over the plant, the stomatal response slows and the photosynthesis rate decreases. “It can be understood that slower stomatal dynamics limit gas exchange,” Wang Yizhou said.   At the same time, the researchers observed BLINK1 transgenic lines that grew during daytime fluctuations in daylight and found that BLINK1 accelerated the stomatal movement. Compared with non-transgenic lines, the ratio of the dry mass or carbon assimilation rate and transpiration rate produced by BLINK1 transgenic lines per unit water evaporation was significantly improved, which proved that BLINK1 is beneficial to carbon assimilation and water utilization.   In addition, the researchers also found that the total dry matter quality of BLINK1 transgenic lines grew similarly to steady-state transformation under water-filled and water-deficient conditions, demonstrating that WUE is improved by increasing stomatal dynamics.   Wang Yizhou said that the research has great application value and hopes to explore its application in some cash crops, such as cotton, to increase crop yield.   Blatt said that the experiment of stomatal guard cells is only part of the research. Next, the research team plans to use optogenetic tools to understand the functional links between different tissue types in plants.
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