State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A & F University, Yangling, Shaanxi, China.
The State Key Laboratory of Genetic Improvement and Germplasm Innovation of Crop Resistance in Arid Desert Regions (Preparation), Key Laboratory of Genome Research and Genetic Improvement of Xinjiang Characteristic Fruits and Vegetables, Institute of Horticulture Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, China.
Plant Biotechnol J. 2023 Oct;21(10):2057-2073. doi: 10.1111/pbi.14112. Epub 2023 Jun 30.
Low temperature is the main environmental factor affecting the yield, quality and geographical distribution of crops, which significantly restricts development of the fruit industry. The NAC (NAM, ATAF1/2 and CUC2) transcription factor (TF) family is involved in regulating plant cold tolerance, but the mechanisms underlying these regulatory processes remain unclear. Here, the NAC TF MdNAC104 played a positive role in modulating apple cold tolerance. Under cold stress, MdNAC104-overexpressing transgenic plants exhibited less ion leakage and lower ROS (reactive oxygen species) accumulation, but higher contents of osmoregulatory substances and activities of antioxidant enzymes. Transcriptional regulation analysis showed that MdNAC104 directly bound to the MdCBF1 and MdCBF3 promoters to promote expression. In addition, based on combined transcriptomic and metabolomic analyses, as well as promoter binding and transcriptional regulation analyses, we found that MdNAC104 stimulated the accumulation of anthocyanin under cold conditions by upregulating the expression of anthocyanin synthesis-related genes, including MdCHS-b, MdCHI-a, MdF3H-a and MdANS-b, and increased the activities of the antioxidant enzymes by promoting the expression of the antioxidant enzyme-encoding genes MdFSD2 and MdPRXR1.1. In conclusion, this study revealed the MdNAC104 regulatory mechanism of cold tolerance in apple via CBF-dependent and CBF-independent pathways.
低温是影响作物产量、品质和地理分布的主要环境因素，极大地限制了果业的发展。NAC（NAM、ATAF1/2 和 CUC2）转录因子（TF）家族参与调节植物的耐寒性，但这些调节过程的机制尚不清楚。本研究中，NAC TF MdNAC104 正向调控苹果的耐寒性。在冷胁迫下，MdNAC104 过表达转基因植株表现出较低的离子渗漏和 ROS（活性氧）积累，但具有较高的渗透调节物质含量和抗氧化酶活性。转录调控分析表明，MdNAC104 直接与 MdCBF1 和 MdCBF3 启动子结合，促进其表达。此外，基于联合转录组学和代谢组学分析以及启动子结合和转录调控分析，我们发现 MdNAC104 通过上调花青素合成相关基因，包括 MdCHS-b、MdCHI-a、MdF3H-a 和 MdANS-b 的表达，在冷胁迫下刺激花青素的积累，同时通过促进抗氧化酶编码基因 MdFSD2 和 MdPRXR1.1 的表达，增加抗氧化酶的活性。综上所述，本研究揭示了 MdNAC104 通过 CBF 依赖和非依赖途径调控苹果耐寒性的机制。
