Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
Planta. 2013 Jul;238(1):65-76. doi: 10.1007/s00425-013-1875-3. Epub 2013 Apr 9.
We have succeeded in isolating an MdMYB110a_JP gene responsible for a red-fleshed trait from a fruit of apple cultivar 'JPP35' ('Jonathan' × 'Pink Pearl'). The isolated MdMYB110a_JP gene was located on chromosome (ch.) 17, which was different from the location of known MdMYB1/10 gene of ch.9, and 'JPP35' and 'Pink Pearl' did not contain the known R 6 :MdMYB10 allele responsible for the red-skin and red-fleshed trait. The MdMYB110a_JP was expressed strongly and weakly in the cortex and core of 'JPP35' fruit, respectively, at the time of coloring start in flesh, and also weakly in flower buds. Following the MdMYB110a_JP expression, the expression of the genes, MdCHS and MdLDOX, that encode the enzymes of the flavonoid pathway, was induced in flesh of 'JPP35' in accordance with anthocyanin accumulation. In contrast, the MdMYB110a_JP gene was not expressed in any tissues in red-skin and white-fleshed 'Fuji', and in red-skin and red-fleshed 'Maypole'. Instead, MdMYB1-1 allele responsible for red-skin trait was expressed in red-skin of 'Fuji' and 'JPP35', and R 6 :MdMYB10 allele responsible for red-skin and red-flesh trait was expressed in red-core and red-cortex in 'Maypole' as expected. Moreover, 35S:MdMYB110a_JP transgenic apple 'JM2' showed a red-foliage phenotype depending on the MdMYB110a_JP expression level. From the results, it was strongly suggested that the red-fleshed phenotype of 'JPP35' fruit was caused by up-regulation of the genes of anthocyanin pathway induced by the MdMYB110a_JP gene.
我们成功地从苹果品种‘JPP35’（‘Jonathan’בPink Pearl’）果实中分离出一个负责红色肉质性状的 MdMYB110a_JP 基因。分离出的 MdMYB110a_JP 基因位于第 17 号染色体上，与位于第 9 号染色体上的已知 MdMYB1/10 基因的位置不同，并且‘JPP35’和‘Pink Pearl’不含有已知的 R6:MdMYB10 等位基因，该等位基因负责红色果皮和红色肉质性状。在果肉开始着色时，MdMYB110a_JP 在‘JPP35’果实的皮层和核中分别强烈和弱表达，在芽中也弱表达。在 MdMYB110a_JP 表达之后，编码类黄酮途径酶的基因 MdCHS 和 MdLDOX 的表达在‘JPP35’果肉中被诱导，与花青素积累一致。相比之下，在红色果皮和白色果肉的‘富士’以及红色果皮和红色果肉的‘梅普尔’中，MdMYB110a_JP 基因在任何组织中都不表达。相反，在红色果皮的‘富士’和‘JPP35’中表达了负责红色果皮性状的 MdMYB1-1 等位基因，在红色核心和红色皮层的‘梅普尔’中表达了负责红色果皮和红色肉质性状的 R6:MdMYB10 等位基因，这与预期一致。此外，35S:MdMYB110a_JP 转基因苹果‘JM2’根据 MdMYB110a_JP 表达水平表现出红色叶表型。结果强烈表明，‘JPP35’果实的红色肉质表型是由 MdMYB110a_JP 基因诱导的花青素途径基因的上调引起的。
