Tsyganov V E, Morzhina E V, Stefanov S Y, Borisov A Y, Lebsky V K, Tikhonovich I A
All-Russia Research Institute for Agricultural Microbiology, Saint-Petersburg-Pushkin.
Mol Gen Genet. 1998 Sep;259(5):491-503. doi: 10.1007/s004380050840.
Two novel non-allelic mutants that were unable to fix nitrogen (Fix ) were obtained after EMS (ethyl methyl sulfonate) mutagenesis of pea (Pisum sativum L.). Both mutants, SGEFix(-)-1) and SGEFix(-)-2, form two types of nodules: SGEFix(-)-1 forms numerous white and some pink nodules, while mutant SGEFix(-)-2 forms white nodules with a dark pit at the distal end and also some pinkish nodules. Both mutations are monogenic and recessive. In both lines the manifestation of the mutant phenotype is associated with the root genotype. White nodules of SGEFix(-)-1 are characterised by hypertrophied infection threads and infection droplets, mass endocytosis of bacteria, abnormal morphological differentiation of bacteroids, and premature degradation of nodule symbiotic structures. The structure of the pink nodules of SGEFix(-)-1 does not differ from that of the parental line, SGE. White nodules of SGEFix(-)-2 are characterised by "locked" infection threads surrounded with abnormally thick plant cell walls. In these nodules there is no endocytosis of bacteria into host-cell cytoplasm. The pinkish nodules of SGEFix(-)-2 are characterised by virtually undifferentiated bacteroids and premature degradation of nodule tissues. Thus, the novel pea symbiotic genes, synm40 and sym33, identified after complementation analysis in SGEFix(-)-1 and SGEFix(-)-2 lines, respectively, control early nodule developmental stages connected with infection thread formation and function.
对豌豆（Pisum sativum L.）进行甲基磺酸乙酯（EMS）诱变后，获得了两个无法固氮的新型非等位突变体。这两个突变体，即SGEFix(-)-1和SGEFix(-)-2，形成两种类型的根瘤：SGEFix(-)-1形成大量白色根瘤和一些粉红色根瘤，而突变体SGEFix(-)-2形成的白色根瘤在远端有一个深色凹陷，也有一些略带粉红色的根瘤。这两种突变均为单基因隐性突变。在这两个株系中，突变体表型的表现都与根的基因型有关。SGEFix(-)-1的白色根瘤的特征是感染丝和感染滴肥大、细菌的大量内吞作用、类菌体的异常形态分化以及根瘤共生结构的过早降解。SGEFix(-)-1粉红色根瘤的结构与亲本株系SGE的根瘤结构没有差异。SGEFix(-)-2的白色根瘤的特征是被异常增厚的植物细胞壁包围的“锁定”感染丝。在这些根瘤中，细菌不会内吞进入宿主细胞的细胞质。SGEFix(-)-2的略带粉红色的根瘤的特征是类菌体几乎未分化以及根瘤组织的过早降解。因此，分别在SGEFix(-)-1和SGEFix(-)-2株系中通过互补分析鉴定出的新型豌豆共生基因synm40和sym33，控制着与感染丝形成和功能相关的早期根瘤发育阶段。
