BACKGROUND The BAHD acyltransferase superfamily exhibits various biological roles in plants, including regulating fruit quality, catalytic synthesizing of terpene, phenolics and esters, and improving stress resistance. However, the copy numbers, expression characteristics and associations with fruit aroma formation of the BAHD genes remain unclear. RESULTS In total, 717 BAHD genes were obtained from the genomes of seven Rosaceae, (Pyrus bretschneideri, Malus domestica, Prunus avium, Prunus persica, Fragaria vesca, Pyrus communis and Rubus occidentalis). Based on the detailed phylogenetic analysis and classifications in model plants, we divided the BAHD family genes into seven groups, I-a, I-b, II-a, II-b, III-a, IV and V. An inter-species synteny analysis revealed the ancient origin of BAHD superfamily with 78 syntenic gene pairs were detected among the seven Rosaceae species. Different types of gene duplication events jointly drive the expansion of BAHD superfamily, and purifying selection dominates the evolution of BAHD genes supported by the small Ka/Ks ratios. Based on the correlation analysis between the ester content and expression levels of BAHD genes at different developmental stages, four candidate genes were selected for verification as assessed by qRT-PCR. The result implied that Pbr020016.1, Pbr019034.1, Pbr014028.1 and Pbr029551.1 are important candidate genes involved in aroma formation during pear fruit development. CONCLUSION We have thoroughly identified the BAHD superfamily genes and performed a comprehensive comparative analysis of their phylogenetic relationships, expansion patterns, and expression characteristics in seven Rosaceae species, and we also obtained four candidate genes involved in aroma synthesis in pear fruit. These results provide a theoretical basis for future studies of the specific biological functions of BAHD superfamily members and the improvement of pear fruit quality.

中文翻译：

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全基因组比较分析七种蔷薇科的BAHD超家族，并在梨中进行表达分析（Pyrus bretschneideri）。

背景技术BAHD酰基转移酶超家族在植物中表现出多种生物学作用，包括调节果实品质，萜烯，酚类和酯类的催化合成以及提高抗逆性。但是，BAHD基因的拷贝数，表达特征以及与水果香气形成的关联仍然不清楚。结果总共从七个蔷薇科的基因组中获得了717个BAHD基因（梨属（Pyrus bretschneideri），苹果属（Malus domestica），李属（Prunus avium），李属（Prunus persica），草莓属（Fragaria vesca），梨属（Pyrus communis）和西方红宝石（Rubus occidentalis）。根据模型植物的详细系统发育分析和分类，我们将BAHD家族基因分为Ia，Ib，II-a，II-b，III-a，IV和V七个组。物种间的同族分析显示，BAHD超家族起源于七个蔷薇科物种，其中有78个同系基因对。不同类型的基因复制事件共同驱动BAHD超家族的扩展，纯化选择主导着以低Ka / Ks比支持的BAHD基因的进化。基于不同发育阶段BAHD基因酯含量与表达水平之间的相关性分析，选择了四个候选基因进行qRT-PCR验证。结果表明，Pbr020016.1，Pbr019034.1，Pbr014028.1和Pbr029551.1是梨果实发育过程中参与香气形成的重要候选基因。结论我们已经彻底鉴定了BAHD超家族基因，并对它们在七个蔷薇科物种中的系统发生关系，扩展模式和表达特性进行了全面的比较分析，还获得了四个与梨果实香气合成有关的候选基因。这些结果为进一步研究BAHD超家族成员的特定生物学功能和提高梨果实品质提供了理论基础。