Data_Sheet_1_Phylogenetic Implications and Functional Disparity in the Chalcone synthase Gene Family of Common Seagrass Zostera marina.docx

Chalcone synthase (CHS) family are plant type III polyketide synthases that participate in the flavonoid synthesis pathway to induce plant resistance to various biotic and abiotic stresses. Zostera marina, a common seagrass, migrated to terrestrial conditions and returned to the sea, achieving the most severe habitat shift of flowering plants. Given the special evolutionary process, we conducted genome-wide, expression and enzyme activity analyses of the ZosmaCHS family to understand its phylogenetic implications. Various duplication modes led to the expansion of 11 CHS homologs in Z. marina. Based on the phylogenetic relationships, ZosmaCHSs were classified into three clades. Further quantitative real time-PCR analyses of the ZosmaCHS homologs showed different light responses and tissue-specific expression, indicating functional diversification of the ZosmaCHSs. Moreover, the ZosmaCHS proteins clustering with the validated chalcone synthases were recombined into prokaryotic expression systems. All the recombinant proteins showed CHS activity to generate naringenin chalcone with varying catalytic efficiencies. ZosmaCHS07 was regarded as the dominant CHS because of its significant light response and the higher catalytic efficiency. Taken together, the disparity of the expression and enzyme activity indicated that sub-functionalization is the primary mechanism of the expansion of the ZosmaCHSs family.

香豆素合酶（Chalcone synthase，CHS）家族是一类植物型III类聚酮合酶，参与类黄酮合成途径，诱导植物对多种生物和非生物胁迫的抵抗力。海草Zostera marina，一种常见的海草，经历了从海洋向陆地迁移，再返回海洋的过程，实现了开花植物中最剧烈的栖息地转变。鉴于其特殊的进化过程，我们对ZosmaCHS家族进行了全基因组、表达和酶活性分析，以理解其系统发育意义。多种复制模式导致了海草Z. marina中11个CHS同源物的扩张。基于系统发育关系，ZosmaCHSs被划分为三个枝系。进一步对ZosmaCHS同源物进行的定量实时PCR分析显示，它们具有不同的光响应和组织特异性表达，表明ZosmaCHSs的功能多样性。此外，与已验证的香豆素合酶聚类的ZosmaCHS蛋白被重组到原核表达系统中。所有重组蛋白均表现出CHS活性，以不同催化效率生成柚皮素香豆酮。ZosmaCHS07由于其显著的光响应和更高的催化效率，被认为是主要的CHS。综上所述，表达和酶活性的差异表明，亚功能化是ZosmaCHSs家族扩张的主要机制。