Feng Shouqian, Sun Shasha, Chen Xiaoliu, Wu Shujing, Wang Deyun, Chen Xuesen
State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
PLoS One. 2015 Nov 4;10(11):e0142112. doi: 10.1371/journal.pone.0142112. eCollection 2015.
Color is an important agronomic trait of pears, and the anthocyanin content of fruit is immensely significant for pear coloring. In this study, an anthocyanin-activating R2R3-MYB transcription factor gene, PyMYB10.1, was isolated from fruits of red sand pear (Pyrus pyrifolia cv. Aoguan). Alignments of the nucleotide and amino acid sequences suggested that PyMYB10.1 was involved in anthocyanin regulation. Similar to PyMYB10, PyMYB10.1 was predominantly expressed in red tissues, including the skin, leaf and flower, but it was minimally expressed in non-red fruit flesh. The expression of this gene could be induced by light. Dual-luciferase assays indicated that both PyMYB10 and PyMYB10.1 activated the AtDFR promoter. The activation of AtDFR increased to a greater extent when combined with a bHLH co-factor, such as PybHLH, MrbHLH1, MrbHLH2, or AtbHLH2. However, the response of this activation depended on the protein complex formed. PyMYB10-AtbHLH2 activated the AtDFR promoter to a greater extent than other combinations of proteins. PyMYB10-AtbHLH2 also induced the highest anthocyanin accumulation in tobacco transient-expression assays. Moreover, PybHLH interacted with PyMYB10 and PyMYB10.1. These results suggest that both PyMYB10 and PyMYB10.1 are positive anthocyanin biosynthesis regulators in pears that act via the formation of a ternary complex with PybHLH. The functional characterization of PyMYB10 and PyMYB10.1 will aid further understanding of the anthocyanin regulation in pears.
颜色是梨的一项重要农艺性状，果实中的花青素含量对梨的着色极为重要。在本研究中，从红砂梨（Pyrus pyrifolia cv. Aoguan）果实中分离出一个花青素激活型R2R3-MYB转录因子基因PyMYB10.1。核苷酸和氨基酸序列比对表明PyMYB10.1参与花青素调控。与PyMYB10相似，PyMYB10.1主要在红色组织中表达，包括果皮、叶片和花朵，但在非红色果肉中表达量极低。该基因的表达可被光诱导。双荧光素酶检测表明PyMYB10和PyMYB10.1均激活AtDFR启动子。当与bHLH辅因子如PybHLH、MrbHLH1、MrbHLH2或AtbHLH2结合时，AtDFR的激活程度更大。然而，这种激活的反应取决于形成的蛋白质复合物。PyMYB10-AtbHLH2比其他蛋白质组合更能激活AtDFR启动子。在烟草瞬时表达检测中，PyMYB10-AtbHLH2也诱导了最高的花青素积累。此外，PybHLH与PyMYB10和PyMYB10.1相互作用。这些结果表明PyMYB10和PyMYB10.1都是梨中花青素生物合成的正调控因子，它们通过与PybHLH形成三元复合物发挥作用。PyMYB10和PyMYB10.1的功能特性将有助于进一步了解梨中花青素的调控机制。
