Abstract
Background. Distribution of root nodule bacteria of soybean in soils of Ukraine is the result of intensive cultivation of soybeans over the last 20 years. During the observation the structure of soybean rhizobia populations for the first time we have determined the strains which significantly differ in phenotypic properties from typical slow-growing bacteria of B. japonicum species previously described. These strains are characterized by high speed growth and we tentatively called them “stains with intensive growth”. The aim of our work was to investigate the genotypic properties of microsymbionts of soybeans with different rates of growth spreading in soils of Ukraine. Materials and methods. The 16S rRNA gene and intergenic 16S-23S rRNA region of six strains - typical representatives of soybean nodule bacteria with slow- and intensive growth-rates was carried out. The strains were picked up from different Ukrainian soils. Results. Analysis of the 16S rRNA nucleotide sequences showed the 100% similarity of slow-growing strains to B. japonicum USDA 6T and USDA 4 ones. This analysis proved propinquity of strains with intensive growth to the strain B. japonicum USDA 127 (USDA 123 group). Representatives of this group possessed increased saprophytic competence so as the examined strains. With use of restriction analysis of ITS intergenic region soybean rhizobia were divided among two ITS types: 1st ITS type - strains with intensive growth, 2nd ITS type - slow- growing strains. According to results of ITS-region sequencing soybean rhizobia form 3 reliably different clusters: two of which include slow-growing strains (group USDA 6 and USDA 4), and a third include soybean microsymbionts with intensive growth (USDA 123 group). Conclusion. On the basis of phenotypic and genotypic (16S rRNA and 16S-23S rRNA) analysis all of the investigated soybean strains of root nodule bacteria were related to the Bradyrhizobium japonicum species. The division of strains by the structure of the ITS-region into two genotypes corresponds to the division of strains into two physiological groups: the strains of an intense and slow growth.
Highlights
Известно, что в процессе фиксации молекулярного азота из атмосферы важная роль принадлежит клубеньковым бактериям, которые способны инициировать образование азотфиксирующих клубеньков на корнях бобовых растений
Serogroups of Rhizobium japonicum in soybean nodules sampled in Iowa
all of the investigated soybean strains of root nodule bacteria were related to the Bradyrhizo bium japonicum species
Summary
Объектами исследований были 6 выделенных нами штаммов — типичных представителей клубеньковых бактерий сои с медленным и интенсивным ростом из Коллекции полезных почвенных микроорганизмов Института сельскохозяйственной микробиологии и агропромышленного производства НААН. Обработанную рестриктазой MspI («Fermentas», США) ДНК анализировали при помощи электрофореза в 4%-м агарозном геле. Секвенирование осуществляли на автоматическом ДНК-секвенаторе ABI PRISM 3130 Genetic Analyzer («Applied Biosystems», США). Обработанную рестриктазой ДНК анализировали при помощи электрофореза в 4%-м агарозном геле. Секвенирование нуклеотидных последовательностей ITS проводили на секвенаторе Genetic Analyzer 3130xl («Applied Biosystems», США). Сравнительный анализ полученных последовательностей с последовательностями базы данных GenBank проводили с помощью программы NCBI Blast 1. Электрофоретический анализ продуктов рестрикции фрагмента гена 16S рРНК штаммов ризобий сои после обработки его рестриктазой MspI: М — маркер молекулярного веса; 1, 2, 3 — штаммы ризобий сои с интенсивным ростом (КВ11, КС19, КС22); 4 — типовой штамм B. japonicum USDA 6Т; 5, 6, 7 — медленнорастущие штаммы ризобий сои (46, КС23, КН10)
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