Functional characterization of two flavone synthase Ⅱ members in citrus  

作　　者：Juan Zheng Chenning Zhao Zhenkun Liao Xiaojuan Liu Qin Gong Chenwen Zhou Yilong Liu Yue Wang Jinping Cao Lili Liu Dengliang Wang Chongde Sun 

机构地区：[1]Plant Growth,Development and Quality Improvement,Zhejiang Provincial Key Laboratory of Integrative Biology of Horticultural Plants,Zhejiang University,Hangzhou,310000,China [2]Quzhou Academy of Agriculture and Forestry Science,Quzhou,324000,China

出　　处：《Horticulture Research》2023年第7期250-264,共15页园艺研究（英文）

基　　金：This research was supported by the China Postdoctoral Science Foundation(2021 M700124 and 2021 M692845);the National Natu-ral Science Foundation of China(32072132);the Fundamental Research Funds for the Central Universities(K20220104).

摘　　要：Polymethoxylated flavones(PMFs),the main form of flavones in citrus,are derived from the flavone branch of the flavonoid biosynthesis pathway.Flavone synthases(FNSs)are enzymes that catalyze the synthesis of flavones from flavanones.However,the FNS in citrus has not been characterized yet.Here,we identified two type II FNSs,designated CitFNSII-1 and CitFNSII-2,based on phylogenetics and transcriptome analysis.Both recombinant CitFNSII-1 and CitFNSII-2 proteins directly converted naringenin,pinocembrin,and liquiritigenin to the corresponding flavones in yeast.In addition,transient overexpression of CitFNSII-1 and CitFNSII-2,respectively,in citrus peel significantly enhanced the accumulation of total PMFs,while virus-induced CitFNSII-1 and CitFNSII-2 genes silencing simultaneously significantly reduced the expression levels of both genes and total PMF content in citrus seedlings.CitFNSII-1 and CitFNSII-2 presented distinct expression patterns in different cultivars as well as different developmental stages.Methyl salicylate(MeSA)treatment reduced the CitFNSII-2 expression as well as the PMFs content in the peel of Citrus sinensis fruit but did not affect the CitFNSII-1 expression.These results indicated that both CitFNSII-1 and CitFNSII-2 participated in the flavone biosynthesis in citrus while the regulatory mechanism governing their expression might be specific.Our findings improved the understanding of the PMFs biosynthesis pathway in citrus and laid the foundation for further investigation on flavone synthesis regulation.

关 键 词：SYNTHESIS converted characterization 

分 类 号：S436.66[农业科学—农业昆虫与害虫防治]