Brassica nap cytoplasmic male sterility is associated with expression of a mtDNA region containing a chimeric gene similar to the pol CMS-associated orf224 gene
Brassica nap cytoplasmic male sterility is associated with expression of a mtDNA region containing a chimeric gene similar to the pol CMS-associated orf224 gene
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DOI：
10.1007/s002940050212
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发表时间：
1997-04-01
期刊：
影响因子：
2.5
通讯作者：
Brown, GG
中科院分区：
文献类型：
--
作者：
LHomme, Y;Stahl, RJ;Brown, GG
在油菜（Brassica napus）中发现了两种不同的细胞质雄性不育（CMS）系统，nap和pol。物理定位研究已经表明，不育pol和可育cam线粒体基因组之间的组织差异仅限于atp6基因上游的一个相对较小的区域。cam mtDNA中缺失约4.5 kb的pol mtDNA片段，该片段包含与atp6共转录的嵌合开放阅读框（orf224），位于nap mtDNA上的不同位置；orf224/atp6基因区域的表达与pal CMS性状高度相关。序列分析现在表明，转置的nap片段包含一个开放阅读框（ORF），与pol orf224相关，但与pol orf224不同。该开放阅读框（orf222）可能编码一个222个氨基酸的蛋白质，与pol orf224基因的预测产物序列相似性为79%。nap orf222与反式剪接的nad5基因的第三外显子和另一个ORF共转录。orf222转录本在nap- CMS中比在nap-细胞质恢复植株中丰富数倍，并且在该区域的质性转录本在CMS和恢复植株之间也存在差异。orf222/nad5c/orf139区域的表达与nap CMS特别相关：在检测的21个线粒体基因区域中，包括nap和可育cam线粒体基因组之间的所有重排列位点和22个已知基因，只有orf222/nad5c/orf139区域检测到维持cam细胞质，nap CMS-和育性恢复nap细胞质-植物之间的转录差异。我们的研究结果表明，orf222/nad5c/orf139区域的表达可能与nap CMS有关，更普遍的是，不同形式的CMS可能与编码结构相似蛋白的基因有关。
Two different cytoplasmic male-sterility (CMS) systems, nap and pol, are found in the oilseed rape (canola) species Brassica napus Physical mapping studies have previously shown that organizational differences between the sterile pol and fertile cam mitochondrial genomes are restricted to a relatively small region immediately upstream of the atp6 gene. An approximately 4.5-kb pol mtDNA segment containing a chimeric open reading frame (orf224) co-transcribed with atp6 is missing from cam mtDNA and located at a different site on nap mtDNA; expression of the orf224/atp6 gene region is highly correlated with the pal CMS trait. Sequence analysis now shows that the transposed nap segment contains an open reading frame (ORF) related to, but distinct from, pol orf224. This open reading frame (orf222) potentially encodes a protein of 222 amino acids possessing 79% sequence similarity to the predicted product of the pol orf224 gene. nap orf222 is co-transcribed with the third exon of the trans-spliced nad5 gene and another ORF. orf222 transcripts are several times more abundant in nap CMS than in fertility restored nap-cytoplasm plants and qualitative transcript differences for the region between CMS and restored plants are found as well. Expression of the orf222/nad5c/orf139 region is specifically correlated with nap CMS: of 21 mitochondrial gene regions examined, including all the sites of rearrangement between the nap and fertile cam mitochondrial genomes and 22 known genes, only the orf222/nad5c/orf139 region detected transcript differences between maintainer cam cytoplasm, nap CMS- and fertility restored nap cytoplasm-plants. Our results suggest that expression of the orf222/nad5c/orf139 region may be associated with nap CMS, and, more generally, that different forms of CMS may be associated with genes encoding structurally similar proteins.