MOLECULAR BASIS OF NUCLEUS-CYTOPLASM HYBRIDS IN WHEAT THAT INDUCE STRUCTRUAL ALTERATIONS OF MITOCHONDRIAL GENOME AND TRANSCRIPTION PATTERNS OF MITOCHONDRIAL GENES

异质体小麦，小麦。摘要norin26与天蚕细胞质结合，表现为光周期敏感细胞质雄性不育（PCMS）。该同种异质系仅在长日照条件下生长时才表现出雌蕊。为了评估PCMS系统的分子基础，我们利用从PCMS不同表型的异质系幼苗中分离的线粒体dna和rna，并用12个线粒体基因进行了Southern和Northern blot分析。同种异质系线粒体DNA的RFLP谱均与普通小麦有较大差异，与亲本品种（即粗穗小麦）的RFLP谱略有差异。这表明相关植物物种之间的核替换会引起线粒体基因组的结构改变。此外，coxIII和orf25检测到的(cr)-N61和fr -突变体的RFLP图谱相同，但与其他异质系的RFLP图谱不同，说明N61和fr -突变体的细胞核中含有一些诱导coxIII和orf25基因周围线粒体基因组结构改变的基因。研究了Ae中atp6和cob的转录模式。草型与青霉型不同。此外，异质系小麦的orf25转录物比包括伊麦在内的同质系小麦的转录物长约300个核苷酸。这表明orf25的转录模式与从PCMS现象中恢复有关。这些数据清楚地显示了核基因组和线粒体之间的相互串扰。这些观察结果提出了一种可能性，即线粒体基因表达的协同控制失败导致的线粒体功能障碍影响了花的形态发生途径，特别是在器官身份步骤中。

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 the long-day condition (>15 h light). To assess molecular basis of the PCMS system, we carried out Southern and Northern blot analyzes by using the mitochondrial DNAs and RNAs isolated from seedlings of alloplasmic lines showing various phenotypes for PCMS and probing them with 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 their parental species, i.e., Ae.crassa. This indicates that nuclear substitutions between the related plant species induce the structural alterations of the mitochondrial genome. Furthermore, RFLP patterns of (cr)-N61 and FR-mutant probed with cox III and orf25 were identical with each other, but different from those of the other alloplasmic lines, indicating the nuclei of N61 and FR-mutant harbor some gene (s) that induces the structural alterations of the mitochondrial genome around the regions of coxIII and orf25 genes. The transcription patterns of atp6 and cob in Ae.crassa type were different from those of T.aestivum type. Furthermore, the orf25 transcript of 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 the 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 organ identity step.