A Beneficial Soil Bacterium Induces Growth, Salt Tolerance And Metabolites Accumulation Of Codonopsis Pilosula (Franch.) Nannf

Bacillus subtilis is non-toxic to humans and animals, non-polluting to the environment, non-pathogenic and highly stress tolerant. Bacillus subtilis can produce a variety of growth hormone and rich antimicrobial substances to promote plant growth, improve plant development and stress tolerance. Recent researches indicated that it can regulate some metabolites accumulation. Codonopsis pilosula (Franch.) Nannf. is a kind of important authentic Chinese herbal medicine cultivated in Gansu Province. The roots of C. pilosula contains rich terpenes, glycosides, amino acids, polysaccharides etc.. C. pilosula lobetyolin has various functions of anti-cancer, anti-bacterium, anti-inflammatory, sedative, anti-hypertensive, anti-gastric acid secretion. In addition, the roots of C. pilosula contains all the seven kinds of essential amino acids, which makes C. pilosula more versatile. In current study, the regulation of B. subtilis GB03 to growth, salt tolerance and metabolites accumulation of C. pilosula was investigated. The main results are as follows:1. After 5,10 and 20 min soaking with GB03 bacterial solution, seed germination vigor of C. pilosula was significantly increased compared with control,5 min soaking had the best effect and significantly increased germination vigor by 211.8%(P< 0.05).5 and 20 min soaking significantly increased germination rate by 8.0% and 11.6%(P< 0.05). Compared with DH5a, LB and water,GB03 bacterial volatiles significantly increased germination vigor by 94.4%,105.9% and 116.8%(P< 0.05) and germination rate by 14.1%,18.7% and 23.6%(P< 0.05), respectively.2. GB03 plays a significant role in promoting the growth of 20,40 and 60 days old C. pilosula seedlings compared with LB with plant height, root length, branch number, single leaf area, chlorophyll content and biomass. GB03 significantly improved transpiration rate, stomatal conductance and net photosynthetic rate and reduced intercellular CO2 concentration, thus promoted the photosynthesis.3. Compared with LB, GB03 increased shoot height, root length, biomass and photosynthesis under 0,50,100 and 150 mM NaCl, significantly lowered leaf osmotic potential by 20.8%(P<0.05)under 100 mM NaCl,thus increased the osmotic adustment ability,significantly reduced MDA content by 41.5%and 7.9%(p<0.05) under 100 and 150 mM NaCl,respeetively.4.Compared with DH5%LB and water,GB03 significantly increased root diameter by 18.1%,30.1%and 26.4%,root volume by 6.5%,37.3%and 25.2%, root dry weight 49.8%,55%and 37.7%and root lObetyolin content by 75.2%,71.5 %and 51.9%(p<0.05),respectively；GB03 increased root total amino acid by 10.6 %,6.2%and 5.6%,shoot total amino acids by 10.8%,0.5%and 4.3%,root essential amino acids by 11.8%,6.7%and 7.7%and shoot essential amino acids improved 13.8%,2.5%and 5.0%,respectively,althoughnot significantly.These results provides not only a theoretical basis for cultivation of medicinal plants under environmental stresses,yield enhancement and quality improvement with potential application values,but a new idea for the researches on beneficial rhizosphere microbe-plants interactions.