Identification Of Endophytic Bacteria StC01 Isolated From Potato And Study On Its Plant-growth-promotion Effect

Endophytic bacteria, which have been found in many plants, are a category of parasiticbacteria being symbiotic with the hosts. It is known that endophytic bacteria play animportant role in plant growth and its adaptation to the environment. In potato, someresearches have been done on endophytic bacteria isolated from plants grown in the fields.This work focused the isolation and identification of endophytic bacteria from in vitropotato plants in our laboratory and the relationship between the bacterium and its host. Theresults were shown below.A strain of endophytic bacterium, named as StC01, was isolated from in-vitro potato(Solanum tuberosum L.) plants. The bacterium is rod, with round, yellow colonies andidentified to be Curtobacterium by employing physic-biochemical methods as well as 16SrRNA gene sequencing analysis.The population density of StC01 is the highest in roots, then in stem, and the lowest inleaves. After applying this bacterium to non-host potato plantlets, the population density ofStC01 increased at the beginning and then come to a stable state.We used lysozyme to remove the endophytic bacterium from the host. The MIC of thelysozyme to the endophytic bacteria is generally 0.4mg mL^-1. In this experience, 2 mg mL^-1of lysozyme would be suitable for removing bacterium from potato plantlets.The endophytic bacterium StC01 could influence the growth of in vitro potato plantletsand the formation of microtubers. The culture showed that the growth of potato plantletswas promoted by the bacterium. Compared with the control, the height of the treatedplantlets increased by 17.85%, the fresh weight increased by 17.56% (the shoots 25.87%,and the roots 2.26%) and the dry weights also increased by 24.46%, of which the shootsand roots increased by 38.13% and 1.67% respectively. In wild potato A, similar results were got between whole plant and upground organ, an increase of 16.29% in dry weightand 10.39% in fresh weight was recorded with whole plant and an increase of 13.72% and10.63% observed with upground organ. Regarding to roots, the dry weight and fresh weightincreased by (the shoots 13.72%, and the roots 24.52%). The dry weight also increased, theaverage dry weight increased by 10.39%, the shoots and roots increased by 24.52% and14.05% respectively. Essay on microtubers induction by inoculating endophytic bacteriaStC01 showed that the existance of endophytic bacteria StC01 decrease the number ofmicrotubers by 6.80% and the fresh and dry weights by 70.18% and 70.84% respectively.