Zhang Lizhi, Yin Shaobo, Wang Mingqian, Liu Zhi, Lv Tianxing, Wang Yanan, Wang Aide, Tan Dongmei, Ji Yinglin
Key Laboratory of Fruit Postharvest Biology (Liaoning Province), College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China.
Liaoning Institute of Pomology, Xiongyue, 115009, China.
New Phytol. 2025 Mar;245(5):2069-2084. doi: 10.1111/nph.20378. Epub 2025 Jan 8.
Cuticular wax is essential for fruit to maintain moisture. Although the wax content of peel surface in apple (Malus spp.) varies, the detailed molecular mechanism remains unclear. Here, we identified the β-ketoacyl-CoA synthase 2 (MdKCS2) differentially expressed between apple peel with low and high wax content by integrating bulked segregant analysis-sequencing and RNA-seq. We found that a 63-bp insertion in the MdKCS2 promoter was the primary reason for apple peel with low wax content. The 63-bp insertion reduced MdKCS2 promoter activity and enhanced the DNA binding with the suppressor MdDOF4.6, decreasing wax biosynthesis by reducing C24 very-long-chain fatty acid (VLCFA). ECERIFERUM 2 (MdCER2) was co-expressed with MdKCS2 and suppressed by MdMYB56, MdbHLH137 and MdDOF4.6, further decreasing C29 alkane content in apple peel with low C24 VLCFA content. Overall, MdKCS2 and MdCER2 are coordinately involved in the wax production of apple peel surface.
角质蜡对于果实保持水分至关重要。尽管苹果（苹果属）果皮表面的蜡质含量存在差异，但其详细的分子机制仍不清楚。在这里，我们通过整合混合分组分析法测序和RNA测序，鉴定了蜡质含量低和高的苹果果皮之间差异表达的β-酮脂酰辅酶A合酶2（MdKCS2）。我们发现MdKCS2启动子中的一个63 bp插入是蜡质含量低的苹果果皮的主要原因。该63 bp插入降低了MdKCS2启动子活性，并增强了与抑制因子MdDOF4.6的DNA结合，通过减少C24超长链脂肪酸（VLCFA）来降低蜡质生物合成。蜡质合成酶2（MdCER2）与MdKCS2共表达，并受到MdMYB56、MdbHLH137和MdDOF4.6的抑制，进一步降低了C24 VLCFA含量低的苹果果皮中的C29烷烃含量。总体而言，MdKCS2和MdCER2协同参与苹果果皮表面蜡质的产生。
