Expression and internal feedback regulation of ACC synthase and ACC oxidase genes in ripening tomato fruit
Expression and internal feedback regulation of ACC synthase and ACC oxidase genes in ripening tomato fruit
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DOI：
10.1093/oxfordjournals.pcp.a029094
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发表时间：
1997-10-01
影响因子：
4.9
通讯作者：
Inaba, A
中科院分区：
文献类型：
--
作者：
Nakatsuka, A;Shiomi, S;Inaba, A
我们研究了1-氨基环丙烷-1-羧酸（ACC）合酶和ACC氧化酶基因表达的正反馈调节是否也在成熟番茄中起作用本研究克隆了ACC合成酶和ACC氧化酶的两个cDNA片段，它们与成熟番茄果实中乙烯生物合成相关基因具有高度同源性，用丙烯处理成熟的绿色果实2天后，可诱导与这些cDNA探针杂交的mRNA的积累。在转青期后成熟的果实中，随着成熟度的增加，果实的红色发展、乙烯产生、ACC含量、ACC合成酶和ACC氧化酶活性增加，果实中两种ACC合酶和一种ACC氧化酶mRNA的丰度从转粉红期开始增加，随后在转红期略有下降，这些mRNA丰度随成熟的增加在很大程度上被乙烯作用抑制剂1-甲基环丙烯（MCP）处理所阻止，这在转基因阶段用MCP处理的果实中最为明显，其中ACC合酶和ACC氧化酶转录物的积累在前两天几乎完全消除，恰好是对照果实具有最高水平的每种mRNA积累的同一阶段，MCP处理2 ~ 4 d后，对转录物积累的抑制恢复到对照水平，MCP处理还降低了乙烯生物合成活性，但这种降低并不反映mRNA积累的减少，这些结果表明，番茄果实乙烯生物合成在基因转录水平上存在强烈的正反馈调节，即使在乙烯产生爆发的阶段也是如此。
We have examined whether or not a positive feedback regulation of gene expression for 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase also operates in ripening tomato (Lycopersicon esculentum) fruit during the burst of ethylene production, Two cDNA fragments for ACC synthase and one for ACC oxidase were cloned with high homology to already known genes involved in ethylene biosynthesis in ripening tomato fruit, Accumulation of mRNAs which hybridize to these cDNA probes were induced in mature green fruit within two days by treatment with propylene, In the fruit ripened from the turning stage, red color development, ethylene production, ACC content, and activities of ACC synthase and ACC oxidase increased as maturity progressed, The abundance of two ACC synthase and one ACC oxidase mRNAs in the fruit increased from the turning to pink stage and were followed by a slight decline towards the red stage, These increases in mRNAs abundance with ripening were prevented to a large extent by treatment with the ethylene action inhibitor, 1-methylcyclopropene (MCP), This was most pronounced in the fruit treated with MCP at the turning stage, in which the accumulation of ACC synthase and ACC oxidase transcripts was almost completely eliminated in the first two d, precisely the same stage at which the control fruit had the greatest level of each mRNA accumulation, The inhibition of transcript accumulation recovered to the control level within two to four d, MCP also decreased ethylene biosynthetic activity, although this decrease did not reflect the reduction in the mRNAs accumulation, These results suggest that a strong positive feedback regulation is involved in ethylene biosynthesis at the gene transcriptional level in tomato fruit, even at the stage with a burst of ethylene production.