Kiwifruit (Actinidia spp.) is a recently domesticated fruit crop with several novel-coloured cultivars being developed. Achieving uniform fruit flesh pigmentation in red genotypes is challenging. To investigate the cause of colour variation between fruits, we focused on a red-fleshed Actinidia chinensis var. chinensis genotype. It was hypothesized that carbohydrate supply could be responsible for this variation. Early in fruit development, we imposed high or low (carbon starvation) carbohydrate supplies treatments; carbohydrate import or redistribution was controlled by applying a girdle at the shoot base. Carbon starvation affected fruit development as well as anthocyanin and carbohydrate metabolite concentrations, including the signalling molecule trehalose 6-phosphate. RNA-Seq analysis showed down-regulation of both gene-encoding enzymes in the anthocyanin and carbohydrate biosynthetic pathways. The catalytic trehalose 6-phosphate synthase gene TPS1.1a was down-regulated, whereas putative regulatory TPS7 and TPS11 were strongly up-regulated. Unexpectedly, under carbon starvation MYB10, the anthocyanin pathway regulatory activator was slightly up-regulated, whereas MYB27 was also up-regulated and acts as a repressor. To link these two metabolic pathways, we propose a model where trehalose 6-phosphate and the active repressor MYB27 are involved in sensing the carbon starvation status. This signals the plant to save resources and reduce the production of anthocyanin in fruits.

中文翻译：

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碳饥饿通过海藻糖 6-磷酸和 MYB27 减少红肉水果中碳水化合物和花青素的积累。


猕猴桃（Actinidia spp.）是一种新近驯化的水果作物，目前正在开发几个新颜色的品种。在红色基因型中实现均匀的果肉色素沉着具有挑战性。为了研究水果之间颜色变化的原因，我们重点研究了红肉猕猴桃品种。中华草基因型。据推测，碳水化合物的供应可能是造成这种变化的原因。在果实发育早期，我们实施高或低（碳饥饿）碳水化合物供应处理；通过在枝条基部施加环带来控制碳水化合物的输入或重新分配。碳饥饿会影响果实发育以及花青素和碳水化合物代谢物的浓度，包括信号分子海藻糖 6-磷酸。 RNA-Seq 分析显示花青素和碳水化合物生物合成途径中的两种基因编码酶均下调。催化海藻糖 6-磷酸合酶基因 TPS1.1a 下调，而假定的调节基因 TPS7 和 TPS11 强烈上调。出乎意料的是，在碳饥饿下，MYB10 的花青素途径调节激活剂略有上调，而 MYB27 也上调并充当阻遏剂。为了将这两种代谢途径联系起来，我们提出了一个模型，其中海藻糖 6-磷酸和活性阻遏物 MYB27 参与感知碳饥饿状态。这表明植物要节省资源并减少水果中花青素的产量。