Ogihara Y, Futami K, Tsuji K, Murai K
Kihara Institute for Biological Research, Yokohama City University, Japan.
Mol Gen Genet. 1997 Jun;255(1):45-53. doi: 10.1007/s004380050473.
Alloplasmic wheat. Triticum aestivum cv. Norin 26, with Aegilops crassa cytoplasm, shows photoperiod-sensitive cytoplasmic male sterility (PCMS). This alloplasmic line expresses pistillody of anthers only when grown in long-day conditions (> 15 h light). To assess the molecular basis of the PCMS, we carried out Southern and Northern hybridization analyses on mitochondrial DNAs and RNAs isolated from seedlings of alloplasmic lines showing various PCMS phenotypes using probes for twelve mitochondrial genes. All RFLP patterns of mitochondrial DNA from alloplasmic lines greatly differed from those of common wheat, and were slightly changed from those of the parental species, i.e., Ae. crassa. This indicates that nuclear substitutions between related plant species induce structural alterations in the mitochondrial genome. Furthermore, RFLP patterns of (cr)-N61 and FR-mutant probed with coxIII and orf25 were identical with each other, but different from those of the other alloplasmic lines, indicating that the nuclei of N61 and FR-mutant harbor some gene(s) that induces structural alterations of the mitochondrial genome in the coxIII and orf25 regions. The transcription patterns of atp6 and cob in Ae. crassa type were different from those of T. aestivum type. Furthermore, the orf25 transcript in alloplasmic wheats was about 300 nucleotides longer than that of euplasmic lines, including the Ae. crassa pure line, suggesting that transcription patterns of orf25 are associated with recovery from the PCMS phenomenon. These data clearly show the mutual cross-talk between the nuclear genome and chondriome. These observations raise the possibility that the dysfunction of mitochondria caused by the failure of a cooperative control of mitochondrial gene(s) expression influences the pathway of flower morphogenesis, especially in the process that determines organ identity.
异质小麦。携带粗厚山羊草细胞质的普通小麦品种Norin 26表现出光周期敏感型细胞质雄性不育（PCMS）。这种异质系仅在长日照条件（光照时长>15小时）下生长时才表现出花药雌蕊化现象。为了评估PCMS的分子基础，我们使用针对12个线粒体基因的探针，对从表现出不同PCMS表型的异质系幼苗中分离出的线粒体DNA和RNA进行了Southern和Northern杂交分析。异质系线粒体DNA的所有RFLP模式与普通小麦的模式有很大差异，与亲本物种即粗厚山羊草的模式略有不同。这表明相关植物物种间的核置换会诱导线粒体基因组的结构改变。此外，用coxIII和orf25探针检测的（cr）-N61和FR-突变体的RFLP模式彼此相同，但与其他异质系不同，这表明N61和FR-突变体的细胞核含有一些能诱导线粒体基因组在coxIII和orf25区域发生结构改变的基因。粗厚山羊草型atp6和cob的转录模式与普通小麦型不同。此外，异质小麦中orf25转录本比包括粗厚山羊草纯系在内的同质系长约300个核苷酸，这表明orf25的转录模式与从PCMS现象中恢复有关。这些数据清楚地表明了核基因组与线粒体基因组之间的相互作用。这些观察结果增加了一种可能性，即线粒体基因表达协同控制失败导致的线粒体功能障碍会影响花形态发生途径，尤其是在决定器官特性的过程中。
