J Exp Bot:中科院武汉植物园韩月彭课题组揭示桃果肉质地多样性与
近日，《JouRNAl Experimental Botany》杂志上在线发表中国科学院武汉植物园韩月彭课题组发表桃果肉质地多样性与基因拷贝数变化相关研究论文，题为“Copy number variation of a gene cluster encoding endopolygalacturonase mediates flesh texture and stone adhesion in peach”，首次揭示了基因拷贝数变化调控果树果实品质性状的新机制，研究结果既对认知果树性状的形成具有理论意义，又为桃等果实质地性状改良提供了工具。
桃原产我国，已有三千多年的栽培历史，其果实风味美馔、营养丰富，深受人们喜爱。桃依据果肉质地差异可分为溶质型和非溶质型。我国主栽桃品种多为溶质桃，果实采后极易软化，不利于贮藏和运输。此外，桃果实成熟时，果肉还分离核和粘核两种类型。已有桃资源可分为离核溶质、粘核溶质和粘核非溶质三种类型，但离核非溶质桃至今尚未见报道。
韩月彭课题组揭示了两个串联排列基因PpendoPGF和PpendoPGM分别控制桃果肉溶质和离核性状，这两个基因都编码多聚半乳糖醛酸酶且两者同源性很高。桃祖先种可能只有PpendoPGM基因，果实表现为粘核溶质;之后PpendoPGM基因发生了缺失和复制两种突变事件，分别导致了粘核非溶质和离核溶质性状的出现(下图)。此外，PpendoPGF基因除控制果肉离粘核性状外，还具有引起果肉溶质的多效性，这导致“离核非溶质”性状无法形成。
桃果肉质地多样性演化机理示意图
原文链接：
Copy number variation of a GENE cluster encoding endopolygalacturonase mediates flesh texture and stone adhesion in peach
原文摘要：
Texture is an important attribute affecting consumer perception of fruit quality. Peach melting flesh and flesh adhesion to stone (endocarp) are simply inherited and controlled by the F-M locus on linkage group (LG) 4. Here, we report that two genes encoding endopolygalacturonase (endoPG) in the F-M locus, designated PpendoPGF and PpendoPGM, are associated with the melting flesh and stone adhesion traits. PpendoPGM controls melting flesh while PpendoPGF has pleiotropic effects on both melting flesh and stone adhesion. The F-M locus has three allelic copy number variants of endoPG, H1 (PpendoPGF and PpendoPGM), H2 (PpendoPGM), and H3 (null). The H2 haplotype represents the ancestral one while the H1and H3 haplotypes are two variants due to duplication and deletion ofPpendoPGM, respectively. Accessions with H1H1, H1H2, or H1H3 genotypes show the freestone or semi-freestone and melting flesh phenotype, while both H2H2 and H2H3 accessions have the clingstone and melting flesh phenotype. The H3H3 accessions have the clingstone and non-melting flesh phenotype. Our study not only demonstrates a driving role of gene copy number variations in flesh texture diversification in fruit trees, but also provides a useful diagnostic tool for early seedling selection in peach breeding programmes.
作者：韩月彭
