Ripening in the tomato Green-ripe mutant is inhibited by ectopic expression of a protein that disrupts ethylene signaling
Ripening in the tomato Green-ripe mutant is inhibited by ectopic expression of a protein that disrupts ethylene signaling
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DOI：
10.1073/pnas.0602319103
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发表时间：
2006-05-16
影响因子：
11.1
通讯作者：
Giovannoni, James J.
中科院分区：
文献类型：
--
作者：
Barry, Cornelius S.;Giovannoni, James J.
为了达到完全成熟，跃变型果实，如番茄，需要植物激素乙烯的合成、感知和信号转导。番茄显性绿熟（Gr）和永不熟2（Nr-2）突变体的不成熟表型是果实组织中乙烯反应降低的结果。此外，与花衰老、脱落和根伸长相关的乙烯反应的子集也在突变体植物中受到影响，但程度较小。使用定位克隆，我们已经确定了一个相同的334-bp的缺失在Gr/Nr-2位点的一个未知的生化功能的基因。与功能突变的显性获得一致，这种缺失导致Gr/ Nr-2的异位表达，这反过来又导致成熟抑制。一个CaMV 35：：GR转基因重建的Gr/Nr-2突变体表型，但不会导致乙烯反应的整体降低，表明在番茄乙烯反应的组织特异性调制。Gr/ Nr-2编码一种进化上保守的蛋白质，其生化功能未知，我们在此将其与乙烯信号传导联系起来。由于Gr/Nr-2与先前描述的番茄Nr（永不成熟）乙烯受体没有序列同源性，我们现在仅将该基因称为GR。GR的鉴定扩展了植物中乙烯信号传导组分的现有库，并为进一步阐明乙烯反应机制和控制作物中乙烯信号特异性提供了工具。
To achieve full ripening, climacteric fruits, such as tomato require synthesis, perception and signal transduction of the plant hormone ethylene. The nonripening phenotype of the dominant Green-ripe (Gr) and Never-ripe 2 (Nr-2) mutants of tomato is the result of reduced ethylene responsiveness in fruit tissues. In addition, a subset of ethylene responses associated with floral senescence, abscission, and root elongation are also impacted in mutant plants, but to a lesser extent. Using positional cloning, we have identified an identical 334-bp deletion in a gene of unknown biochemical function at the Gr/Nr-2 locus. Consistent with a dominant gain of function mutation, this deletion causes ectopic expression of Gr/ Nr-2, which in turn leads to ripening inhibition. A CaMV35::GR transgene recreates the Gr/Nr-2 mutant phenotype but does not lead to a global reduction in ethylene responsiveness, suggesting tissue-specific modulation of ethylene responses in tomato. Gr/ Nr-2 encodes an evolutionary conserved protein of unknown biochemical function that we associate here with ethylene signaling. Because Gr/Nr-2 has no sequence homology with the previously described Nr (Never-ripe) ethylene receptor of tomato we now refer to this gene only as GR. Identification of GR expands the current repertoire of ethylene signaling components in plants and provides a tool for further elucidation of ethylene response mechanisms and for controlling ethylene signal specificity in crop plants.