Wheat Stomatal Responses To Abiotic Environment Factor And Technological Platform For Relevant Studies

Plant stomata are important channels for air exchange between plants and external environment,which involve in photosynthesis and transpiration and play important roles in biological processes such as stress responses.But untill now,very little work has been carried out in stomatal movement dynamics of major crop wheat and the technological platform for relevant studies have not been established yet.In this study,we established a platform for stomatal studies and analyzed the rules governing the wheat stomatal responses to key physiological factors and climatic factors in comparison with Arabidopsis.The platform built in this study compose of bioassay tank system,infrared camera-electronic balance system,environment controlling chamber system and photosynthetic analyzer-microscope system.Through this platform,stomatal responses of wheat and Arabidopsis to climatic factors?temperature,CO₂ and humidity?and physiological factors?K⁺?pH and ABA?.We set up a stomatal bioassay tank system to analyze stomatal responses of detached epidermal strips in wheat with dumbbell-shaped guard cells to K⁺,pH and ABA in comparison with those of Arabidopsis with kidney-shaped guard cells.The results show that the stomata of both wheat and Arabidopsis open to the largest level under 100 mmol?L^-1 KCl.There are slightly different in terms of stomatal responses to pH.Stomatal aperture of wheat reaches to the maximal level in pH 6.2,while that value in Arabidopsis is pH5.8.Stomata of both wheat and Arabidopsis come to close after challenged by ABA.In addition,alteration range of stomata aperture in wheat is significantly wider than those in Arabidopsis.K⁺induces 284.99%and 35.25%of stomatal alteration in wheat and Arabidopsis,respectively.Those values are94.54%and 33.30%for pH while 81.4%and 56.78%for ABA.Infrared camera-electronic balance system can assess the wheat capability of drought resistance by measuring water loss rate and leaf temperature in combination with stomatal movement data obtained by the application of 10?mol·L^-1ABA.The results showed that water loss rate of Zhongnongda 5 and Zhongnongda 6 under the extreme drought stress was mainly determined by stomatal aperture.The similar trends can be found in Nongda 1817 and Nongda3331.While the main determinant is stomatal density for water loss rate of Yanda1817and Beinong6.Environment controlling chamber system well controls the humidity,CO₂ concentration,and temperature in the chamber and an infrared camra installed outside the top of the chamber can monitor the leaf temperature alteration inside the chamber through a germanium glass window,which indicated indirectly the stomatal status.The results reveal that the ratio of Leaf temperature to Environmental temperature?L/E?quickly drops within 10 mins after low humidity treatment,then rises until a plateau level.As for heat treatment,L/E value rises in the beginning and then drops to a plateau level.Low temperature can drive L/E up-down-up and finally to stable value.L/E value can keep increasing under High CO₂ concentration before reaching to the plateau level.Photosynthetic analyzer-microscope system can visualize the realtime stomatal movement in responses to climatic factors.The results show that high data consistency can be obtained using this system and Environment controlling chamber for high CO₂ and low humidity treatments.But they are not the cases for temperature treatments,which might be due to only part of the leaf in wheat challenged by treatments.Through the four technological systems,we can comprehensively explore the stomatal responses patterns in wheat to physiological and climatic factors,build the physiological basis for wheat genetic improvement in stress resistance,and provide a good reference of stomatal studies in other gramineous crops.