花青素苷合成途径调控红花槭叶色转化的分子机理

Red maple (Acer rubrum L.) is one of the most colorful leaf trees in the fall. The change of red maple leaf color is closely related with the content and kinds of anthocyanins. However, the molecular mechanism of anthocyanidins biosynthesis pathway on leaf color change of red maple is poorly understood. In this project, red-leaf variety ‘Yanhong’ bred by our group was used to investigate the mechanism. The transcripts of the leaf during the processes of color change were sequenced, and compared. There branchs of anthocyanin synthesis pathway genes F3H, F3'H, F3'5'H and DFR, are found in the transcriptome database, which underlines ‘Yanhong’ has 3 branchs of anthocyanin biosynthesis pathway. The intermediate products, final products, and enzyme system comprising related to anthocyanidins will be inferred, surveyed and verified by HPLC method. The key genes expression of anthocyanins synthesis will be quantitatively analyzed by real-time PCR. Other red maple varieties will be used to verify the key genes and anthocyanidins biosynthesis branch pathway based on real-time PCR and HPLC methods. The relation of the key genes expression, anthocyanin glycoside composition in anthocyanins biosynthesis branch pathway, and the leaf color will be evaluated, and the mapping of anthocyanidins biosynthesis branch pathway will be presented. The results can clarify the molecular mechanism on leaf color of red maple, and provide theoretical base for the molecular improvement of red maple leaf color.

红花槭是秋季叶色最为丰富的树种之一，已有研究显示其叶色转变与花青素苷含量、种类密切相关，但对其花青素苷合成途径及叶色转变的分子机理了解甚少。申请人以自主选育的红花槭‘艳红’为材料，对其变色前后的叶片进行了转录组测序与比对分析，花青素苷合成3大途径关键基因F3H、F3′H、F3′5′H及DFR，均在其转录组数据库中发现，显示该品系具有花青素苷合成的3大途径；拟进一步解析其花青素苷合成途径中间产物、最终产物及酶系组成，利用HPLC技术进行验证；并对上述关键基因进行Real-time PCR定量分析。利用其它色系红花槭材料，对其花青素苷合成分支途径关键基因及产物进行Real-time PCR、HPLC验证分析。关联分析花青素苷合成分支途径、关键基因表达、花青素苷组成与叶片呈色之间的关系，明确不同色系红花槭花青素苷合成分支途径。以解析红花槭秋季叶色形成的分子机理，为其分子改良提供理论依据。

【项目的背景】红花槭是叶色最为丰富的树种之一，秋天叶片由绿色变成黄色、橙黄色、红色及中间色，花青素苷的种类及含量是其叶色差异的关键主导因子。但对红花槭花青素苷的种类组成及其合成途径尚不清楚，有待对红花槭花青素苷合成途径进一步详细解析，以解析秋叶树种红花槭叶色转变的分子机理，为红花槭的叶色改良提供理论依据。【主要研究内容】以绿叶、红叶和黄叶为材料，用超高效液相色谱串联质谱和高通量RNA测序的方法分别进行转录组和代谢组分析。量化分析了花青素苷合成途径中间产物、最终产物及酶系组成；解析了红花槭叶色突变体中花青素、叶绿素、类胡萝卜素等主要色素合成途径基因表达差异；并对关键基因进行Real-time PCR定量分析。通过生物信息学方法及数据关联分析，解析不同叶色形成的内在原因。【重要结果及关键数据】结果表明，在红叶-绿叶、黄叶-绿叶、红叶-黄叶3个比较组中，3个比较组中，转录组测序分别检测出28536、43017、27110个差异表达基因。代谢组正离子模式下分别检测出1377、1793、1098个差异积累代谢物，负离子模式下分别检测出789、699、6778个差异积累代谢物。红花槭花青素苷的生物合成中，有48个差异表达基因和29个差异积累的相关代谢物。红叶与绿叶相比，花青素苷合成通路中89.5%的基因表达量增加；黄叶与绿叶相比，花青素苷合成通路中66.7%的基因表达量增加。同时，矢车菊素-3-（6’’-乙酰半乳糖苷）和矢车菊素-3-阿拉伯糖苷含量大幅上升，为红花槭叶片变色的主要驱动因子。解析了红花槭叶片花青素、叶绿素、类胡萝卜素合成途径基因的表达模式，阐明了不同色系红花槭叶片呈色的物质基础。【科学意义】对红花槭叶色良种的选育具有指导意义。