Wang Chuanhong, Zhi Shuang, Liu Changying, Xu Fengxiang, Zhao Aichun, Wang Xiling, Tang Xing, Li Zhengang, Huang Ping, Yu Maode
College of Biotechnology, Southwest University, No.2 Tiansheng Road, BeiBei District, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, No.2 Tiansheng Road, BeiBei District, Chongqing 400716, China.
The Sericultural and Apicultural Research Institute, Yunnan Academy of Agricultural Sciences, Mengzi, Yunnan 661100, China.
Plant Physiol Biochem. 2017 Jun;115:107-118. doi: 10.1016/j.plaphy.2017.03.014. Epub 2017 Mar 23.
Chalcone synthase (CHS) is the pivotal enzyme that catalyzes the first committed step of the phenylpropanoid pathway leading to flavonoids. Here, five CHS genes were determined in mulberry (Morus atropurpurea Roxb.). Interestingly, phylogenetic analysis tended to group three MaCHSs in the stilbene synthase (STS) family and initially annotated these as MaSTSs. A co-expression system that harbored a 4-coumarate:CoA ligase gene and one of the candidate genes was established to determine the functions of this novel gene family. The fermentation result demonstrated that MaSTS in fact encoded a CHS enzyme, and was consequently retermed MaCHS. Tissue-specific expression analysis indicated that MaCHS1/MaCHS2 was highly abundant in fruit, and MaCHS4 had significant expression in root bark, stem bark and old leaves, while MaCHS3 and MaCHS5 were more expressed in old leaves. Subcellular localization experiments showed that MaCHS was localized to the cytoplasm. Transcription levels suggested MaCHS genes were involved in a series of defense responses. Over-expression of MaCHS in transgenic tobacco modified the metabolite profile, and resulted in elevated tolerance to a series of environmental stresses. This study comprehensively evaluated the function of MaCHS genes and laid the foundation for future research on MaCHS in mulberry.
查尔酮合酶（CHS）是催化苯丙烷类途径中通向类黄酮的第一个关键步骤的关键酶。在此，在桑（Morus atropurpurea Roxb.）中鉴定出五个CHS基因。有趣的是，系统发育分析倾向于将三个MaCHS基因归为芪合酶（STS）家族，并最初将它们注释为MaSTS。建立了一个包含4-香豆酸：CoA连接酶基因和一个候选基因的共表达系统，以确定这个新基因家族的功能。发酵结果表明，MaSTS实际上编码一种CHS酶，因此将其重新命名为MaCHS。组织特异性表达分析表明，MaCHS1/MaCHS2在果实中高度丰富，MaCHS4在根皮、茎皮和老叶中有显著表达，而MaCHS3和MaCHS5在老叶中表达较多。亚细胞定位实验表明，MaCHS定位于细胞质。转录水平表明MaCHS基因参与了一系列防御反应。在转基因烟草中过表达MaCHS改变了代谢物谱，并导致对一系列环境胁迫的耐受性提高。本研究全面评估了MaCHS基因的功能，为今后桑树中MaCHS的研究奠定了基础。
