title: Sequential functioning of Sym-13 and Sym-31, two genes affecting symbiosome development in root nodules of pea (Pisum sativum L.).
abstract: Two Fix- mutants of pea (Pisum sativum L.) which are unable to fix molecular nitrogen, E135f (sym-13) and Sprint-2Fix- (sym-31), were crossed to create the doubly homozygous recessive line, named RBT (sym-13, sym-31). The ultrastructural organization of nodules of the RBT line was compared with that of each of the two parental mutant lines and with the original wild-type genotypes of the cultivars Sparkle and Sprint-2. It was shown that the RBT line is similar to the mutant line Sprint-2Fix- in having abnormal symbiosome composition and bacteroids with relatively undifferentiated morphology. Because the phenotypic manifestation of the sym-31 mutant allele suppresses the phenotypic manifestation of the sym-13 mutant allele, it is concluded that the function of the gene Sym-31 (which is mutated in the Sprint-2Fix- line) is necessary at an earlier stage of symbiosome development than the gene Sym-13 (which is mutant in the E135f line).
authors.affiliation: All-Russia Research Institute for Agricultural Microbiology, St. Petersburg-Pushkin.
authors.forename: A Y
authors.initials: AY
authors.lastname: Borisov
authors.forename: S M
authors.initials: SM
authors.lastname: Rozov
authors.forename: V E
authors.initials: VE
authors.lastname: Tsyganov
authors.forename: E V
authors.initials: EV
authors.lastname: Morzhina
authors.forename: V K
authors.initials: VK
authors.lastname: Lebsky
authors.forename: I A
authors.initials: IA
authors.lastname: Tikhonovich
mesh_terms: D017343:Genes, Plant / Q000235:genetics*; D009154:Mutation; D018532:Pisum sativum / Q000235:genetics / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology* / Q000648:ultrastructure; D012231:Rhizobium / Q000502:physiology* / Q000648:ultrastructure; D013559:Symbiosis / Q000235:genetics*