Expression Analysis of Hexokinase Genes in Kiwifruit during Postharvest Softening

Abstract

To solve the problem of the rapid softening of postharvest kiwifruit, the effect of 10 mmol/L N-acetyl-D-glucosamine (NAG) treatment on physiological changes, hexokinase (HXK) activity and AcHXKs gene expression in ‘Hongyang’ kiwifruit during postharvest ripening. The results showed that compared with the control group, exogenous NAG treatment could effectively inhibit the respiration rate and ethylene production of kiwifruit, delay the decline of firmness and total acid content, as well as the hydrolysis of starch and pectin, thereby maintaining a lower soluble solid content. In addition, NAG inhibited HXK activity and AcHXK3 expression level, thus affecting sugar and respiratory metabolism. Moreover, the expression of AcHXK7, 8 and 9 was upregulated, which was positively correlated with firmness and probably involved in glucose sensor-mediated postharvest softening of kiwifruit. In conclusion, NAG treatment can induce the differential expression of AcHXK3, 7, 8 and 9, thereby delaying kiwifruit postharvest ripening via catalytic and regulatory functions. These results may provide a theoretical basis for the mechanism of kiwifruit postharvest softening, and also help researchers develop novel strategies for kiwifruit preservation.

Keywords

• kiwifruit; n-acetyl-d-glucosamine; postharvest softening; hexokinase