The Effects of Bagging on Color Change and Chemical Composition in ‘Jinyan’ Kiwifruit (Actinidia chinensis)

To explore the effect of bagging on the nutritional quality and color of kiwifruit (Actinidia spp.), the fruits of yellow-fleshed kiwifruit cultivars were analyzed after bagging treatment. Bagging treatment promoted the degreening of mesocarp and increased brightness. Bagging significantly reduced the accumulation of dry matter, titratable acids, starch, sucrose, fructose, and glucose during kiwifruit development. Additionally, bagging significantly reduced the accumulation of chlorophyll and carotenoids during development, whereas after debagging, the chlorophyll and carotenoid contents were significantly increased. Gene expression analysis showed that during most of the fruit development periods, the chlorophyll biosynthesis genes AcRCBS, AcGLUTR, and AcCHLG, and degradation genes AcCBR, AcPAO, AcPPH, AcCLH, and AcSGR had significantly lower expression levels in bagged fruit. Bagging also inhibited the expression of carotenoid metabolism genes, especially AcSGR and AcLCYB, which may play a key role in the process of fruit development during bagging by decreasing the accumulation of chlorophyll and carotenoids in kiwifruit. Additionally, bagging significantly reduced the content of AsA. The expression of the AsA biosynthesis genes AcPMI2, AcGPP2, and AcGalDH in bagged fruit was significantly lower than in the control, indicating that these may be the key genes responsible for the difference in the accumulation of AsA after bagging.