No 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).

No abstract

The main number of genome editing events in plant objects obtained during the last decade with the help of specific nucleases zinc finger (ZFN), transcription activator-like effector nucleases (TALEN), and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas are the microindels causing frameshift and subsequent gene knock-out. The knock-ins of genes or their parts, i.e., the insertion of them into a target genome region, are between one and two orders of magnitude less frequent. First and foremost, this is associated with the specific features of the repair systems of higher eukaryotes and the availability of the donor template in accessible proximity during double-strand break (DSB) repair. This review briefs the main repair pathways in plants according to the aspect of their involvement in genome editing. The main methods for increasing the frequency of knock-ins are summarized both along the homologous recombination pathway and non-homologous end joining, which can be used for plant objects.

An electrophoretic analysis of histone Hi of Pisum sativum L. was carried out using the collection of 883 accessions of cultivated peas originating from different regions of the Old World. The closely linked genes of five Hi subtypes (2-6) form a cluster, the gene of subtype 1 being located on another chromosome. The fast allelic variant of subtype 1 was not observed to the north of the 44th parallel. The frequency of allele 1 of subtype 5 displays a latitudinal dine and is strongly correlated with the sum of aerial temperatures over the vegetational period. Allele 1 of subtype 6 prevails all over the Old World except Central Asia and China, where allele 3 predominates. From this area allele 3 frequency forms a declining gradient. Alleles of subtypes 2, 3 and 4 exhibit no regularities in their geographic patterns. The data indicate that alleles of Hi subtype 5 and, possibly, subtype 1 in garden pea were subjected to climatically-dependent natural selection under conditions of primitive farming (without conscious selection).