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The response to reduced light intensity of two contrasting cultivars Puma Sunny (shade intolerant) and Gongzi (shade tolerant) was characterized in terms of plant height, the root/shoot ratio, photosynthetic capacity, and the morphology and ultrastructure of their chloroplasts and phloem companion cells. The initial response to shading of cultivar Puma Sunny plants was to extend their stems, and while the equivalent response of cultivar Gongzi was less marked. Shading depressed the maximum relative electron transport rate (rETR) in both cultivars, and while the efficiency of light capture in cultivar Puma Sunny was compromised by shading, this was not the case for cultivar Gongzi. Low levels of incident light inhibited the formation of starch grains in the chloroplast and increased the volume of interspace between the grana lamellae. In cultivar Puma Sunny, but less so in cultivar Gongzi, the chloroplasts became more slender and the stroma lamellae more swollen. Adjusting chloroplast morphology by developing extra layers of grana lamellae and maintaining the integrity of the phloem companion cells are both adaptations which help make ‘Gongzi’ a more shade-tolerant cultivar.
Fruit bagging is a popular agricultural practice that has been widely used to physically protect fruit. However, the application of fruit bags usually has various effects on fruit quality. In this study, three kinds of paper bags with different colors and transmittance were applied to investigate their effects on the skin coloration and related gene expression of peach (Prunus persica). Our findings showed that bagging treatment inhibited anthocyanin accumulation and the expression of related structural and regulatory genes in the peach pericarp. To a certain extent, the inhibitory effects were negatively correlated with the light transmittance of these paper bags. The expression of MYB10.1 was also suppressed by fruit bagging and was highly consistent with anthocyanin content in peach pericarps, which indicated that MYB10.1 might have a critical role in the light-mediated regulation of anthocyanin production in peach pericarps. These findings further enrich our theoretical knowledge of the regulation of anthocyanin synthesis in peach fruit and provide a theoretical basis for common horticultural practices.