Genetic variation in the promoter of an R2R3-MYB transcription factor determines fruit malate content in apple (Malus domestica Borkh.)
Genetic variation in the promoter of an R2R3-MYB transcription factor determines fruit malate content in apple (Malus domestica Borkh.)
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DOI：
10.1093/plphys/kiab098
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发表时间：
2021-02-24
期刊：
影响因子：
7.4
通讯作者：
Han, Zhenhai
中科院分区：
文献类型：
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作者：
Jia, Dongjie;Wu, Peng;Han, Zhenhai
苹果苹果酸积累机理的研究水果有助于改善其风味品质，增强其对人体健康的益处。在这里，我们分析了苹果酸含量作为一个主要由遗传效应决定的数量性状。在之前的研究中，我们发现了一个R2R3-MYB转录因子，命名为MdMYB44，它是苹果酸含量的qtl08.1(定位于8号染色体的数量性状基因座)的候选基因。在本研究中，我们证实了MdMYB44通过抑制苹果酸相关基因MA1(Al激活的苹果酸转运蛋白9)、MA10(P型ATPase 10)、MdVHA-A3(V型ATPase A3)和MdVHA-D2(V型ATPase D2)的启动子活性来负向调节果实苹果酸的积累。MdMYB44启动子上的两个单核苷酸多态(SNPs)，即SNP A/G和SNP T/-，被实验证明与果实苹果酸含量有关。在SNP A存在的情况下，MdMYB44启动子中的TATA盒增强了MdMYB44启动子的基础活性。SNP T的存在增强了碱性-螺旋-环-螺旋转录因子MdbHLH49与MdMYB44启动子的结合，导致MdMYB44转录水平增加，苹果酸积累减少。此外，MdbHLH49与MdMYB44相互作用，增强MdMYB44的活性。这两个SNPs可用于酸苹果和非酸苹果的筛选，为苹果育种提供了一个有价值的选择果实酸度的工具。本研究对于深入了解苹果果实苹果酸积累的复杂分子机制，促进苹果种质创新具有重要意义。
Deciphering the mechanism of malate accumulation in apple (Malus domestica Borkh.) fruits can help to improve their flavor quality and enhance their benefits for human health. Here, we analyzed malate content as a quantitative trait that is determined mainly by genetic effects. In a previous study, we identified an R2R3-MYB transcription factor named MdMYB44 that was a candidate gene in qtl08.1 (quantitative trait locus mapped to chromosome 8) of fruit malate content. In the present study, we established that MdMYB44 negatively regulates fruit malate accumulation by repressing the promoter activity of the malate-associated genes Ma1 (Al-Activated Malate Transporter 9), Ma10 (P-type ATPase 10), MdVHA-A3 (V-type ATPase A3), and MdVHA-D2 (V-type ATPase D2). Two single-nucleotide polymorphisms (SNPs) in the MdMYB44 promoter, SNP A/G and SNP T/-, were experimentally shown to associate with fruit malate content. The TATA-box in the MdMYB44 promoter in the presence of SNP A enhances the basal activity of the MdMYB44 promoter. The binding of a basic-helix-loop-helix transcription factor MdbHLH49 to the MdMYB44 promoter was enhanced by the presence of SNP T, leading to increased MdMYB44 transcript levels and reduced malate accumulation. Furthermore, MdbHLH49 interacts with MdMYB44 and enhances MdMYB44 activity. The two SNPs could be used in combination to select for sour or non-sour apples, providing a valuable tool for the selection of fruit acidity by the apple breeding industry. This research is important for understanding the complex molecular mechanisms of fruit malate accumulation and accelerating the development of germplasm innovation in apple species and cultivars.