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《Acta Pedologica Sinica》 2018-03
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Mechanism of Plasticity of Root Vessel Structure of Ziziphus jujuba var. spinosa Adapting Ecotopes along a Natural Drought Gradient

ZHU Guanglong;CHEN Xubing;Irshad Ahmad;LIU Jiawei;ZHI Wenfang;JIAO Xiurong;ZHOU Guisheng;Joint International Research Laboratoryof Agriculture and Agri-Product Safety,the Ministry of Educationof China,Institutes of Agricultural Science and Technology Development,Yangzhou University;Jiangsu Provincial Key Lab of Crop Genetics&Physiology,Yangzhou University;  
【Objective】Root system of a plant plays a vital role in drought tolerance. Water and nutrients are absorbed by roots, which have to adapt themselves in structure and function to adverse environments for survival, and the structure determines their function and efficiency of water/nutrient translocation. However, little information is available about plasticity of the vessel in structure in the root system of the plant growing in different ecotopes. So, study on plasticity of the vessel is the key to understanding plant adaption to ecotopes along a gradient of drought.【Method】Therefore, this study was done to explore plasticity of rootvessels in structure of Ziziphus jujuba var. spinosa growing in different ecotopes, such as Yantai, Shijiazhuang, Yinchuan and Turpan along a natural drought gradient. Roots were sampled from the four ecotopes for analysis of characteristics of the vessels in the secondary xylem of the roots using segregation process and microscopy.【Result】The root vessels could be classified into six types and varied sharply in number and structure with the ecotope. The vessels could be sorted into three types according to their tail structure: no tail, tail on one end and tails on both ends, which demonstrate specific adaptive properties and regularity. From Yantai to Turpan with the drought aggravating, the reticulate vessel increased in thickness of the wall, but decreased in length of tails; the pitted vessel decreased in length, width and diameter, but did reversely in thickness of the wall and length of the tails; the spiral vessel decreased in length, thickness of the wall and length of the tails; the scalariform vessel decreased in length, width and diameter and evolved from tailless to multi-tailed; and the xylon declined gradually in length, width and thickness of the wall, but did reversely in length of the tails. In addition, compared with the tree in Yantai, the trees in Shijiazhuang, Yinchuan and Turpan had the pitted vessel decreased by 17.63%, 11.23% and 7.67% in length, the spiral vessel decreased by 20.2%, 11.4% and14.6% in thickness of the wall, the scalariform vessel decreased by 29.1%, 37.6%, 31.4% and 20.7%, 48.5%, 28.6% in length and width, and the xylon decreased by 0.7%, 1.5% and 2.6% in length, by 2.2%, 4.7% and 5.4% in width and by 33.2%, 29.3% and 22.1% in thickness of the wall, respectively. 【Conclusion】All the findings indicate that the root vessels of Ziziphus jujuba var. spinosa are high in plasticity and vary in structure with the ecotope to adapt to local conditions for better adsorption and transport of water nutrients. All the changes in vessel structure improve tenacity and extendability of the roots, enabling the root to go deeper into the soil to adsorb more water from deep soil layers to make up the loss through transpiration in dry environments, thus improving the plants' resistance to drought and adaption to harsh environments to ensure normal growth.
【Fund】: 江苏省高校自然科学基金(17KJB210008);; 扬州大学高层次人才科研启动项目(137011178)资助~~
【CateGory Index】: S665.1
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