Sweetpotato (Ipomoea batatas [L.] Lam) is one of the most important food crops, as it ensures food and nutrition security in the face of climate change, given its high carbohydrate, antioxidant (carotenoid), dietary fiber, and mineral contents. The Orange protein of sweetpotato (IbOr) shows high molecular chaperone activity. Previously, we showed that transgenic sweetpotato plants overexpressing the IbOr gene exhibited strong tolerance to abiotic stresses such as high temperature (47 °C) and drought, owing to the increased contents of carotenoids including β-carotene. Interestingly, the expression of the sweetpotato carotenoid cleavage dioxygenase 4 (IbCCD4) gene was also significantly up-regulated in IbOr-overexpressing sweetpotato plants. In this study, we confirmed that the IbCCD4 gene is highly expressed in carotenoid-rich leaves and storage roots of three types of sweetpotato cultivars, each with a different storage root color (pale yellow, orange, and purple). The IbCCD4 protein showed interaction with IbOr in yeast two-hybrid and pull-down assays. Additionally, in vitro, carotenoid cleavage assays indicated that β-carotene is the major substrate of IbCCD4. Interestingly, the interaction between IbCCD4 and IbOr did not affect β-carotene degradation. Further characterization of the IbCCD4 gene in transgenic sweetpotato plants will provide new insights into carotenoid homeostasis under severe stress conditions.

甘薯（Ipomoea batatas [L.] Lam）是最重要的粮食作物之一，因为它具有高碳水化合物，抗氧化剂（类胡萝卜素），膳食纤维和矿物质含量，可在面对气候变化时确保食品和营养安全。甘薯（IbOr）的橙色蛋白质具有高分子伴侣活性。以前，我们表明过表达IbOr基因的转基因甘薯植物对非生物胁迫（如高温（47°C）和干旱）表现出较强的耐受性，这是由于包括β-胡萝卜素在内的类胡萝卜素含量增加所致。有趣的是，甘薯类胡萝卜素裂解双加氧酶4（IbCCD4）基因的表达在IbOr中也显着上调。-过表达甘薯植物。在这项研究中，我们证实了IbCCD4基因在三种类甘薯品种的富含类胡萝卜素的叶片和贮藏根中高表达，每种贮藏根的颜色不同（淡黄色，橙色和紫色）​​。在酵母双杂交和下拉分析中，IbCCD4蛋白显示与IbOr相互作用。另外，在体外，类胡萝卜素裂解测定表明β-胡萝卜素是IbCCD4的主要底物。有趣的是，IbCCD4和IbOr之间的相互作用并不影响β-胡萝卜素的降解。转基因甘薯植物中IbCCD4基因的进一步表征将为严重胁迫条件下的类胡萝卜素稳态提供新的见解。