Physiological Mechanism of Grafting to Alleviate Low Potassium Stress in Tobacco
In order to gain a clear idea of whether K content in tobacco can be increased by grafting onto K+ efficient rootstocks and to clarify the response mechanism of potassium cycling in tobacco plant under K stress,a mutual grafting experiment has been conducted in two varieties of tobacco in different levels of K supply.The results showed that the K stress and plant growth in the common cultivar tobacco Yunyan 87 were significantly alleviated by grafting.The data of the whole plant K content and tobacco hypocotyls'net K+ flux demonstrate that potassium stress makes plants more inclined to maintain K+ in the shoot rather than in the root.In addition,when K deficiency occurred,the time required for the downward net K+ flux to decrease to stable levels in treatments with Wufeng No.2 as the rootstock was less than that in treatments with Yunyan 87 as the rootstock.The results of net K+ flux in the roots indicated that K channel proteins and transporters play different roles in two rootstocks in terms of potassium tolerance.Meanwhile,qRT-PCR results suggested that the increased circulation efficiency of K+ between the shoots and roots in plants constitutes an important adaptation mechanism by which Wufeng No.2 adapts to low potassium stress.In view of the experiment findings,it is concluded that the K+ up-take,transport efficiency and plant growth of Yunyan 87 can be enhanced by grafting with Wufeng No.2 tobacco rootstock.The relief of potassium stress by grafting can be attributed to its ability to respond to the occurrence of K deficiency in the external environment more rapidly and to enhance transport capacity in the xylem and phloem.
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万方数据
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