[Genetic potential of local endemic forms of the pea (Pisum sativum L.) on the basis of nitrogen fixation and productivity].

Morphological and symbiotic traits were studied in local endemic forms of the pea originating from Egypt, Syria, Afghanistan, and Palestine. A number of endemic forms exceeded the zoned Druzhnaya variety of the fodder pea in productivity of the seeds in field and greenhouse experiments. In order to improve nodulation and nitrogen fixation, endemic forms were crossed with the supernodulating K301 mutant marked by the nod4 gene. Recurrent selection of lines up to F5,6 generations was conducted with an estimation of productivity, nodulation, and nitrogen fixation. The most promising recurrent lines with a high productivity, active nodulation, and high nitrogen fixation were obtained during the crossing of endemic forms with the recurrent line marked by the nod4 gene. The line was previously created during the crossing between the Druzhnaya variety and the supernodulating K301 mutant marked by the nod4 gene.

[Study of dominant symbiotic mutants of pea Pisum sativum L].

Phenogenetic studies of four symbiotic hypernodulating mutants of pea (Pisum sativum L.) induced from seeds of cultivar Rodno by chemical mutagen EMS were conducted. All mutants have improved symbiotic traits, i.e., an increased number of root nitrogen fixating nodules and high activity of nitrogenase. Symbiotic traits were shown to be inherited dominantly. Mutants grown in the field or in a greenhouse showed superiority over the original cultivar in productivity. An important feature of hypernodulating mutants was found that is responsible for the appearance of high-height productive plants in F2 after crossing mutants and the original cultivar. Constant lines retaining the ability for high-level production up to the F5 generation were created based on individual plants.

[Expression of the symbiotic nod4 pea gene against various genotypic backgrounds].

Experiments on the effect of genotypic environment on the expression of the nod4 gene, responsible for supernodulation in pea, were performed. The genotypic background was found to affect the manifestation of both major symbiosis-related traits (number of nitrogen-fixing bacterial nodules and nitrogenase activity) and productivity-related traits (stem height, seed number, and seed weight), which form the pleiotropic complex of the mutant gene. Using recurrent selection, we developed supernodulating lines significantly exceeding the original mutant line and studied them up to generations F5-F6. Of special importance is the fact that these lines showed high levels of nodulation and nitrogen fixation. The results are discussed from the viewpoint of breeding.