| Apple(Malus domestica)is a delicious fruit of high economic value.However,numerous destructive fungi affect apples,greatly limiting their production.Many studies have shown that salicylic acid and jasmonic acid improve plant resistance to fungal diseases,but the potential mechanisms of cytokinin action and fungal diseases remain largely unreported.The IPT gene family encodes the proteins required for cytokinin biosynthesis and plays a central role in plant biological stress.In our previous study,we found that the disease resistance in autotetraploid apple was much better than ‘Hanfu’ and analyzed the transcriptome data between ‘Hanfu’ diploid and autotetraploid apple.We found that MdIPT8 gene is significantly differentially upregulated expressed in autotetraploid apple.Therefore,we focus on the gene functions in biotic stress responses.In this study,‘Hanfu’ diploid apple is used as the test material.On the one hand,the leaves of ‘Hanfu’apple are treated with Colletotrichum gloeosporioides to observe endogenous cytokinin content and MdIPT8 gene expression.On the other hand,an overexpression vector containing the coding region of MdIPT8 gene is constructed,and apple transgenic plants are generated by Agrobacterium-mediated genetic transformation,which lay the foundation for functional gene research in apple.The results are following:1.The endogenous trans-zeatin content of ‘Hanfu’ leaves is induced by C.gloeosporioides infection,and the resistance of apple leaves to C.gloeosporioides is improved when 0.02 mg/m L exogenous transzeatin is applied.2.The expression of MdIPT8 gene is induced by C.gloeosporioides.3.The MdIPT8 protein,when fused to the green fluorescent protein,identified the chloroplast as the site of protein localization.4.Using Agrobacterium-mediated method,the ‘Hanfu’ apple MdIPT8 gene is introduced into ‘Hanfu’apple and three overexpressing transgenic lines are obtained.Overexpression of MdIPT8 increases the resistance of C.gloeosporioides infection in ‘Hanfu’ apple. |
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