Tatsuki Miho, Hayama Hiroko, Nakamura Yuri
National Institute of Fruit Tree Science, NARO, Fujimoto, 2-1, 305-8605, Tsukuba, Ibaraki, Japan.
Planta. 2009 Jul;230(2):407-17. doi: 10.1007/s00425-009-0953-z. Epub 2009 May 30.
Ethylene plays a crucial role in apple fruit ripening. Ethylene receptors have been identified and are known to be negative regulators of ethylene signalling. We examined ethylene receptors MdERS1 and MdERS2 in 1-MCP-treated and untreated fruit and leaves of cultivar 'Orin' and 'Fuji' apples. MdERS1 and MdERS2 transcription increased rapidly after harvest in control fruit, but in 1-MCP-treated fruit, increases were delayed for 30 days. However, MdERS1 and MdERS2 protein levels behaved differently. MdERS1 decreased gradually in both the control and 1-MCP treatments. MdERS2, however, increased gradually in control 'Fuji' and remained steady in 1-MCP-treated 'Fuji' but remained low in 'Orin'. Exogenous ethylene treatment of fruit increased MdERS1 and MdERS2 expression with slightly decreased protein levels. The ratios of proteins to mRNAs were much lower in 'Orin' fruit, and they decreased with ethylene treatment in both cultivars. However, protein to transcript ratio was higher in 'Fuji' ethylene treated fruit than in air- and ethylene-treated 'Orin' fruit. MdERS1 and MdERS2 transcript levels were increased by exogenous ethylene treatment in air pre-treated leaves, but MdERS1 and MdERS2 protein levels did not change or decrease with ethylene treatment, and the ratio of protein to mRNA was lower in ethylene-treated leaves. Differences between transcription and protein levels may be due to receptor turnover differences in the presence or absence of ethylene. Furthermore, MdERS1 and MdERS2 protein stabilities in the presence of ethylene were different in the two cvs. 'Orin' and 'Fuji'.
乙烯在苹果果实成熟过程中起着关键作用。乙烯受体已被鉴定出来，并且已知是乙烯信号传导的负调节因子。我们研究了在经过1-甲基环丙烯（1-MCP）处理和未处理的‘奥琳’和‘富士’苹果品种的果实及叶片中的乙烯受体MdERS1和MdERS2。在对照果实中，收获后MdERS1和MdERS2的转录迅速增加，但在经过1-MCP处理的果实中，增加延迟了30天。然而，MdERS1和MdERS2的蛋白质水平表现不同。在对照和1-MCP处理中，MdERS1都逐渐下降。然而，MdERS2在对照‘富士’中逐渐增加，在经过1-MCP处理的‘富士’中保持稳定，但在‘奥琳’中一直较低。对果实进行外源乙烯处理会增加MdERS1和MdERS2的表达，蛋白质水平略有下降。‘奥琳’果实中蛋白质与mRNA的比率要低得多，并且在两个品种中，该比率都随着乙烯处理而降低。然而，经过乙烯处理的‘富士’果实中蛋白质与转录本的比率高于经过空气处理和乙烯处理的‘奥琳’果实。在空气预处理的叶片中，外源乙烯处理会增加MdERS1和MdERS2的转录水平，但MdERS1和MdERS2的蛋白质水平在乙烯处理后没有变化或下降，并且在经过乙烯处理的叶片中蛋白质与mRNA的比率较低。转录水平和蛋白质水平之间的差异可能是由于乙烯存在与否时受体周转差异所致。此外，在两个品种‘奥琳’和‘富士’中，乙烯存在时MdERS1和MdERS2的蛋白质稳定性不同。
