State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong, China; Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Tai'an, Shandong, China.
State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong, China; Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Tai'an, Shandong, China.
Biochem Biophys Res Commun. 2018 Jun 2;500(2):405-410. doi: 10.1016/j.bbrc.2018.04.088. Epub 2018 Apr 14.
The cold-induced metabolic pathway and anthocyanin biosynthesis play important roles in plant growth. In this study, we identified a bHLH binding motif in the MdMYB15L protein using protein sequence analyses. Yeast two-hybrid and pull-down assays showed that MdMYB15L could interact with MdbHLH33. Overexpressing MdMYB15L in red-fleshed callus inhibited the expression of MdCBF2 and resulted in reduced cold tolerance but did not affect anthocyanin levels. Chip-PCR and EMSA analysis showed that MdMYB15L could bind the type II cis-acting element found in the MdCBF2 promoter. Overexpressing MdMYB15L in red-fleshed callus overexpressing MdbHLH33 also reduced cold tolerance and reduced MdbHLH33-induced anthocyanin biosynthesis. Knocking out the bHLH binding sequence of MdMYB15L (LBSMdMYB15L) prevented LBSMdMYB15L from interacting with MdbHLH33. Overexpressing LBSMdMYB15L in red-fleshed callus overexpressing MdbHLH33 also reduced cold tolerance and reduced MdbHLH33-induced anthocyanin biosynthesis. Together, these results suggested that an apple repressor MdMYB15L might play a key role in the cold signaling and anthocyanin metabolic pathways.
冷诱导代谢途径和花色苷生物合成在植物生长中起重要作用。本研究通过蛋白序列分析鉴定了 MdMYB15L 蛋白中的 bHLH 结合基序。酵母双杂交和 pull-down 实验表明，MdMYB15L 可以与 MdbHLH33 相互作用。在红色果肉愈伤组织中过表达 MdMYB15L 抑制了 MdCBF2 的表达，导致对低温的耐受性降低，但不影响花色苷水平。Chip-PCR 和 EMSA 分析表明，MdMYB15L 可以结合在 MdCBF2 启动子中发现的 II 型顺式作用元件。在红色果肉愈伤组织中过表达 MdMYB15L 和 MdbHLH33 也降低了对冷胁迫的耐受性和 MdbHLH33 诱导的花色苷生物合成。敲除 MdMYB15L 的 bHLH 结合序列（LBSMdMYB15L）阻止了 LBSMdMYB15L 与 MdbHLH33 的相互作用。在红色果肉愈伤组织中过表达 LBSMdMYB15L 和 MdbHLH33 也降低了对冷胁迫的耐受性和 MdbHLH33 诱导的花色苷生物合成。这些结果表明，苹果抑制因子 MdMYB15L 可能在冷信号和花色苷代谢途径中起关键作用。
