Determining antagonistic and growth promoting factors of bacteria strains against cucumber Fusarium wilt and studies on their biological effects
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DOI:10.7606/j.issn.1000-7601.2018.03.20
Key Words: Fusarium oxysporum f.sp. cucumerinum  cucumber Fusarium wilt  antagonistic bacteria  Bacillus atrophaeus
Author NameAffiliation
MA Xing College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
DONG Xing-chen College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
ZHANG Jian College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
LUO chao-yue College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
DENG De-lei College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
ZHANG Chun-hong College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
WANG You-ling College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
QIU Hui-zhen College of Resources and Environmental Sciences/Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
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Abstract:
      The strains with antagonistic activity against cucumber Fusarium wilt pathogen (FOC, Fusarium oxysporum f.sp. cucumerinum) were screened. Two strains named QHZ[CD*2]Yb1 and QHZ[CD*2]Yb2 were obtained by primary and repeated screening, which showed stable and strong antagonism. It produced inhibition zones with respective width of 3.37mm and 3.42mm and their diameter more than 2.7cm, and the inhibition rates were up to 61.9% and 62.3% by the plate confrontation method. Two strains were preliminarily identified as Bacillus atrophaeus based on the morphological, physiological and biochemical identifications, and the 16S rDNA sequence analyse. In addition, the experiment determining antagonistic and growth promoting factors was conducted to examine the capacity of the strains. The results showed that Yb1 and Yb2 produced multiple antagonistic and growth promoting factors.The antibacterial rate of lipopeptide extracted from the two strains were 57.4% and 58% respectively.The secretion of growth hormone(IAA)were 1.56mg·L-1 and 3.69mg·L-1 respectively. The amount of solubilizing P were 0.77mg·L-1 and1.19mg·L-1 respectively.Siderophore and casease can also be produced in two strains. Seed germination test showed that the bacteria suspension of Yb1 and Yb2 could promote the germination of cucumber seeds.According to the pot experiment of bacteria’s biological effect,Whether the strains were combined or not, it not only had obviously biocontrol effect on cucumber Fusarium wilt, but also significantly increased plant biomass and the amount of bacteria and actinomycetes in cucumber plants rhizosphere, reduced the number of fungi and Fusarium oxysporum. The biocontrol efficiency using the combination of two strains was significantly higher than that of Yb1 or Yb2, which made the incidence of cucumber fusarium wilt reduce 11.11% and the plants biomass increase 56.7%. In conclusion, both Yb1 and Yb2 have well biocontrol potential against FOC. Moreover, Yb1 and Yb2 in combination showed the highest efficiency compared with Yb1 or Yb2 alone.