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Chinese Journal Of Biological Control ›› 2020, Vol. 36 ›› Issue (5): 751-760.DOI: 10.16409/j.cnki.2095-039x.2020.05.016

• RESEARCH REPORTS • Previous Articles     Next Articles

Inspection on the Mechanisms of the Proportional Change of Fusarium oxysporum Associated Bacteria and Its Influence on Cucumber Growth

JING Yuling, GUO Rongjun, LI Shidong   

  1. Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
  • Received:2020-02-14 Online:2020-10-08 Published:2020-11-20

Abstract: Hyphae-associated bacteria exist in a narrow area where fungi react strongly with soil. Continuous cropping of cucumber resulted in the community change of Fusarium oxysporum f. sp. cucumerinum (Foc) associated bacteria. In this study, different bacterial mixtures of HB-1(33:8:7:6)and HB-2(41:12:2:1)were designed according to the abundance of Rhizobium sp., Achromobacter sp., Shinella sp., Stenotrophomonas sp. in hyphosphere of Foc baiting from the corresponding treatments of un-monoculture and monoculture soil. The effects of the proportion changes of the representative hyphae-associated bacterial strains 76, 77, 252 and 29 on cucumber growth were assessed by plate-incubating bioassay, the result showed that the cucumber seedlings in treatment HB-1 was higher than that in treatment HB-2. The interactions between strains were determined by "V" pair-culturing of bacterial suspension on root exudate plates, and the effects of the hyphae-associated bacterial culture filtrate on the growth of itself and other strains were determined in 96-well plates. Interaction was observed among the four bacteria. The culture filtrate of strain 76 significantly promoted the growth of strain 77, and the secondary metabolite of strain 77 inhibited its own growth. The abilities of four bacteria to utilize different carbon sources of synthetic cucumber root exudates were measured in 96-well plates. The results showed that strain 76 utilized different carbon sources bes-U, and strain 252 grew best in the root exudate medium containing glucose as main carbon source. Bacterial mixtures of HB-1 and HB-2 grew well in five kinds of root exudates with different carbon. The determination of IAA production of the four strains showed that strain 76 had the highest capability to produce IAA persistently, up to 19.4 mg/L, followed by strain 252 with a highest IAA yield of 22.1 mg/L at 60 h. The IAA produced by mixture HB-1 is higher than that by mixture HB-2. In a conclusion, the interaction among bacteria and the utilization ability of cucumber root exudates resulted in the community change of hyphae-associated bacteria, and IAA production is an important factor to influence cucumber growth. This study provides new clues for keeping plants healthy.

Key words: hyphae-associated bacteria, cucumber growth, carbon utilization, interaction

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