Endophytic actinobacteria genus Cellulomonas in an artificially created association with potato meristem
Ryabova O.V., PhD, researcher
North-East Agricultural Research Institute, Kirov, Russia
The article presents the results of the study of ability of the auxins producing strain Cellulomonas sp. 7, isolated from the inner tissues of roots of winter rye (Secale cereale L.) on sod-podzolic soil and manifests growth-stimulating activity in the host plant, to interact with other crop - potato (Solanum tuberosum L.), propagated in conditions in vitro. The study was conducted on two varieties of potato -Rozhdestvensky and Darik. Creating of microbe-plant association in vitro was carried out by coating of cell suspension of studied isolates on the surface of the explant. As a result of inoculationCellulomonas sp. 7 actively colonizes the surface and internal tissues of the shoots (0.5×109 and 4.2×106 CFU/g, respectively on 30th day after treatment) and roots (3.4×107 and 9.4×103 CFU/g) ofplant of Rozhdestvensky variety. Population density of colonization of the phylloplane (2.6×109 CFU/g) and rhizoplane (0.7×107 CFU/g) of potato Darik by cellulomanades was on the same level aspotato Rozhdestvensky; however in the internal tissues of the shoots of this variety bacteria were found in smaller number (2.1×103 CFU/g) than that of the Rozhdestvensky variety and in surface-sterilized roots did not show up at all. Observation for three passages for colonization of potato meristem plants revealed that their numbers in phytosphere of variety Rozhdestvensky remained at a high level throughout the experiment. Stable colonization by studied isolate of phytosphere of potato Darik observed for only two passages; in the third passage the bacteria could not be identified on the plants. The obtained results demonstrate the ability of Cellulomonas sp. 7 to interact with potato meristem. The density of the population of bacteria in plant tissues, as well as the stability of the association is largely dependent on the variety of plant accessories: a closer connection of the studied isolates was with the variety Rozhdestvensky than Darik. The possibility of regulation of potatomeristem growth by actinobacteria of genus Cellulomonas in conditions in vitro is shown. Treatment of explants Cellulomonas sp. 7 promotes an increase in shoots height, the mass and the coefficient of plant propagation. Significant growth-promoting effect of the inoculation of plants is achieved by selection of the optimal concentration of inoculum.
Keywords: actinobacteria, tissue culture, potato, colonization, endophytes, plant hormones