南農吳俊團隊發現紅梨色澤調控的新途徑

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近日，南京農業大學吳俊教授團隊在Plant Journal在線發表題為「Map-based cloning of the pear gene MYB114 identifies an interaction with other transcription factors to coordinately regulate fruit anthocyanin biosynthesis」的研究論文，該研究通過梨高密度遺傳圖譜定位紅色性狀，實現圖位克隆重要功能基因R2R3-MYB轉錄因子PyMYB114，並解析了該基因調控梨果皮花青苷生物合成的分子機理，這也是梨上首次通過遺傳圖譜定位結合基因組序列信息挖掘的重要性狀功能基因。

Fig.1 The model for the regulation of anthocyanin biosynthesis in red-skinned pears.

紅皮梨因具有漂亮的外觀和豐富的花青苷而受到消費者的廣泛認可，具有較高的經濟價值。但是亞洲的栽培梨品種中，大部分以綠皮和褐皮為主，紅皮梨品種稀少。而西洋梨品種中具有較多的紅色品種，近年來我國先後引進了一些紅色西洋梨品種，但是由於氣候條件和品種適應性等原因，栽培面積受到很大的限制。近年來，我國育種工作者雖然選育了部分紅皮梨品種，但是多數表現著色受環境因子影響大，特別是在高溫多濕的南方地區，著色不穩定或不著色。因此，研究紅梨的著色機制對改善果實的品質具有重要的意義。

該團隊在研究中利用梨的SNP和SSR標記構建的高密度遺傳連鎖圖譜在連鎖群LG5上定位控制紅色性狀的主效QTL，對應染色體區間序列信息，篩選出調控色澤形成的重要基因R2R3-MYB轉錄因子PyMYB114，結合轉錄組分析和基因功能驗證，發現ERF/AP2轉錄因子PyERF3與PyMYB114共表達，它們與輔助因子PybHLH3形成調控複合體結合到花青苷代謝通路的基因PyDFR, PyANS, PyUFGT的啟動子區域，激活下游基因的表達，促進花青苷的生物合成，這也是首次發現ERF轉錄因子參與果實色澤的調控。研究還發現，新基因PyMYB114與已報道的PyMYB10有著色增強的效應，並在草莓果實和煙草葉片中得到驗證。研究結果解析了轉錄因子間互作協同調控花青苷生物合成的機制，拓展了果實色澤調控機制的作用網路，為梨等果實色澤性狀的遺傳改良提供了新的思路和基因資源。

該研究在南京農業大學梨工程技術研究中心完成，該中心也是國家梨產業體系技術研發中心的依託單位，姚改芳博士和明美玲碩士為該論文的第一作者，吳俊教授為通訊作者，相關工作得到了國家自然科學基金，國家梨產業技術體系和江蘇省傑出青年科學基金等項目的資助。

Map-based cloning of the pear geneMYB114identifies an interaction with other transcription factors to coordinately regulate fruit anthocyanin biosynthesis

Gaifang Yao, Meiling Ming, Andrew C. Allan, Chao Gu, Leiting Li, Xiao Wu, Runze Wang, Yaojun Chang Kaijie Qi, Shaoling Zhang and Jun Wu

Red fruits are popular and widely accepted by consumers because of an enhanced appearance and enriched anthocyanins. The molecular mechanism of anthocyanin regulation in red-skinned pears has been studied, and the genes encoding the biosynthetic steps and several transcription factors (TFs) have been characterized. In this study, a candidate R2R3 MYB TF, PyMYB114, was identified by linkage to the quantitative trait loci (QTL) for red skin color on linkage group 5 (LG5) in a population of Chinese pear (Pyrus bretschneideri). The function of PyMYB114 was verified by transient transformation in tobacco leaves and strawberry and pear fruits, resulting in the biosynthesis of anthocyanin. Suppression of PyMYB114 could inhibit anthocyanin biosynthesis in red-skinned pears. The ERF/AP2 transcription factor PyERF3 was found to interact with PyMYB114 and its partner PybHLH3 to co-regulate anthocyanin biosynthesis, as shown by a dual luciferase reporter system and a yeast two-hybrid (Y2H) assay. In addition, the transcript abundance of PyMYB114 and PyMYB10 were correlated, and co-transformation of these two genes into tobacco and strawberry led to enhanced anthocyanin biosynthesis. This interaction network provides insight into the coloration of fruits and the interaction of different TFs to regulate anthocyanin biosynthesis.

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