Apple fruit firmness is a crucial index for measuring the internal quality of apples,which influences palatability,storage capacity and transportability.The primary cause of reduced firmness during fruit development i...Apple fruit firmness is a crucial index for measuring the internal quality of apples,which influences palatability,storage capacity and transportability.The primary cause of reduced firmness during fruit development is the hydrolysis of cell wall polysaccharides.Xyloglucan endotransglycosylase/hydrolase(XTH)is a key enzyme involved in the depolymerization of cell wall polysaccharides,but the mechanism of its involvement in the formation of fruit firmness remains unclear.Here,we identified the gene MdXTH2 by integrating metabolomic and transcriptomic data,and analyzed its function and molecular mechanism in the formation of apple fruit firmness.The results showed downward trends in both fruit frmness and cell wall components throughout fruit development.The contents of cell wall material,cellulose,and hemicellulose in various apple varieties exhibited signifcant positive correlations with frmness,with total correlation coeffcients of 0.862,0.884,and 0.891,respectively.Overexpression of MdXTH2 signifcantly increased fruit frmness in apple and tomato,inhibited fruit ripening,and signifcantly suppressed the growth of calli.The upstream transcription factor MdNAC72 of the MdXTH2 gene can promote the expression of fruit ripening-related genes.Furthermore,dual-luciferase,yeast one-hybrid,and electrophoretic mobility shift assay(EMSA)demonstrated that MdNAC72 down-regulates the transcription of MdXTH2 by binding to its promoter.In summary,the results of this study provide a strategy for examining fruit quality regulation and a theoretical basis for breeding apple varieties with moderate frmness through genetic improvement.展开更多
基金supported by the National Natural Science Foundation of China(32302683)the China Postdoctoral Science Foundation(2024M752636)+1 种基金the Earmarked Fund for the China Agriculture Research System(CARS-27)the Project of Weinan Experimental Demonstration Station of Northwest A&F University,China(2024WNXNZX-1)。
文摘Apple fruit firmness is a crucial index for measuring the internal quality of apples,which influences palatability,storage capacity and transportability.The primary cause of reduced firmness during fruit development is the hydrolysis of cell wall polysaccharides.Xyloglucan endotransglycosylase/hydrolase(XTH)is a key enzyme involved in the depolymerization of cell wall polysaccharides,but the mechanism of its involvement in the formation of fruit firmness remains unclear.Here,we identified the gene MdXTH2 by integrating metabolomic and transcriptomic data,and analyzed its function and molecular mechanism in the formation of apple fruit firmness.The results showed downward trends in both fruit frmness and cell wall components throughout fruit development.The contents of cell wall material,cellulose,and hemicellulose in various apple varieties exhibited signifcant positive correlations with frmness,with total correlation coeffcients of 0.862,0.884,and 0.891,respectively.Overexpression of MdXTH2 signifcantly increased fruit frmness in apple and tomato,inhibited fruit ripening,and signifcantly suppressed the growth of calli.The upstream transcription factor MdNAC72 of the MdXTH2 gene can promote the expression of fruit ripening-related genes.Furthermore,dual-luciferase,yeast one-hybrid,and electrophoretic mobility shift assay(EMSA)demonstrated that MdNAC72 down-regulates the transcription of MdXTH2 by binding to its promoter.In summary,the results of this study provide a strategy for examining fruit quality regulation and a theoretical basis for breeding apple varieties with moderate frmness through genetic improvement.
