Antisense inhibition of the Nr gene restores normal ripening to the tomato Never-ripe mutant, consistent with the ethylene receptor-inhibition model
Antisense inhibition of the Nr gene restores normal ripening to the tomato Never-ripe mutant, consistent with the ethylene receptor-inhibition model
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DOI：
10.1104/pp.124.3.1079
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发表时间：
2000-11-01
期刊：
影响因子：
7.4
通讯作者：
Grierson, D
中科院分区：
文献类型：
--
作者：
Hackett, RM;Ho, CW;Grierson, D
激素乙烯调节植物生长发育的许多方面，包括果实成熟。在转基因番茄（Lycopersicon esculentum）植株中，乙烯生物合成基因的反义抑制导致成熟被抑制或延迟。显性番茄突变体永不成熟（Nr）对乙烯不敏感，果实不成熟。Nr表型是由NX基因编码的乙烯受体突变引起的，这样它就不能再结合激素了。NR与拟南芥乙烯受体具有同源性。对拟南芥中乙烯感知的研究表明，受体通过“受体抑制”的作用模式运作，在缺乏激素的情况下，它们积极抑制乙烯反应，而在与乙烯结合时则不活跃。在成熟的番茄果实中，NX的表达受到高度调控，在成熟开始时表达增加，与乙烯产量增加一致。这种表达表明在成熟过程中需要NX基因产物，并暗示通过番茄NR受体的乙烯信号可能不受受体抑制。利用反义抑制法研究了NR在番茄果实成熟过程中的作用，并确定了其作用方式。我们通过抑制突变的Nr基因来恢复Nr果实的正常成熟，表明该受体不是正常成熟所必需的，并证实受体抑制是Nr蛋白的作用模式。
The hormone ethylene regulates many aspects of plant growth and development, including fruit ripening. In transgenic tomato (Lycopersicon esculentum) plants, antisense inhibition of ethylene biosynthetic genes results in inhibited or delayed ripening. The dominant tomato mutant, Never-ripe (Nr), is insensitive to ethylene and fruit fail to ripen. The Nr phenotype results from mutation of the ethylene receptor encoded by the NX gene, such that it can no longer bind the hormone. NR has homology to the Arabidopsis ethylene receptors. Studies on ethylene perception in Arabidopsis have demonstrated that receptors operate by a "receptor inhibition" mode of action, in which they actively repress ethylene responses in the absence of the hormone, and are inactive when bound to ethylene. In ripening tomato fruit, expression of NX is highly regulated, increasing in expression at the onset of ripening, coincident with increased ethylene production. This expression suggests a requirement for the NX gene product during the ripening process, and implies that ethylene signaling via the tomato NR receptor might not operate by receptor inhibition. We used antisense inhibition to investigate the role of NR in ripening tomato fruit and determine its mode of action. We demonstrate restoration of normal ripening in Nr fruit by inhibition of the mutant Nr gene, indicating that this receptor is not required for normal ripening, and confirming receptor inhibition as the mode of action of the NR protein.