Group of Molecular Biology of Fruit Trees, College of Horticulture, Shenyang Agricultural University, Shenyang, Liaoning, China.
Group of Fruit Germplasm Evaluation & Utilization, College of Horticulture, Shenyang Agricultural University, Shenyang, Liaoning, China.
Plant Biotechnol J. 2019 Dec;17(12):2341-2355. doi: 10.1111/pbi.13151. Epub 2019 May 26.
To expand the cultivation area of apple (Malus×domestica Borkh.) and select resistant varieties by genetic engineering, it is necessary to clarify the mechanism of salt and osmotic stress tolerance in apple. The MdMYB46 transcription factor was identified, and the stress treatment test of MdMYB46-overexpressing and MdMYB46-RNAi apple lines indicated that MdMYB46 could enhance the salt and osmotic stress tolerance in apple. In transgenic Arabidopsis and apple, MdMYB46 promoted the biosynthesis of secondary cell wall and deposition of lignin by directly binding to the promoter of lignin biosynthesis-related genes. To explore whether MdMYB46 could coordinate stress signal transduction pathways to cooperate with the formation of secondary walls to enhance the stress tolerance of plants, MdABRE1A, MdDREB2A and dehydration-responsive genes MdRD22 and MdRD29A were screened out for their positive correlation with osmotic stress, salt stress and the transcriptional level of MdMYB46. The further verification test demonstrated that MdMYB46 could activate their transcription by directly binding to the promoters of these genes. The above results indicate that MdMYB46 could enhance the salt and osmotic stress tolerance in apple not only by activating secondary cell wall biosynthesis pathways, but also by directly activating stress-responsive signals.
为了通过基因工程扩大苹果（Malus×domestica Borkh.）的种植面积并选择抗性品种，有必要阐明苹果耐盐和渗透胁迫的机制。鉴定了 MdMYB46 转录因子，并对 MdMYB46 过表达和 MdMYB46-RNAi 苹果株系进行了胁迫处理测试，结果表明 MdMYB46 可以增强苹果的耐盐和渗透胁迫能力。在转基因拟南芥和苹果中，MdMYB46 通过直接结合木质素生物合成相关基因的启动子，促进次生细胞壁的生物合成和木质素的沉积。为了探讨 MdMYB46 是否可以协调胁迫信号转导途径与次生壁的形成协同作用，以增强植物的胁迫耐受性，筛选出与渗透胁迫、盐胁迫和 MdMYB46 转录水平正相关的 MdABRE1A、MdDREB2A 以及脱水响应基因 MdRD22 和 MdRD29A。进一步的验证测试表明，MdMYB46 可以通过直接结合这些基因的启动子来激活它们的转录。上述结果表明，MdMYB46 不仅可以通过激活次生细胞壁生物合成途径，还可以通过直接激活应激响应信号来增强苹果的耐盐和渗透胁迫能力。
