| Banana wilt caused by Fusarium oxysporum f.sp cubense(FOC)has caused the most serious losses to the rapidly developing banana industry at home and abroad.Among them,banana fusarium wilt caused by FOC4 is the most serious harm to banana planting industry.Up to now,there is still no effective prevention and treatment method that can effectively control the epidemic occurrence of this disease in a long term.At present,the ideal and promising measures are disease resistance breeding and biological control.Base on the previous work isolating a bacillus amyloliquefaciens ZJ6-6,which there is obvious inhibitory effect against FOC4,The investigation of characteristics of bio-control was carried out in order to developof the environment friendly bio-control measures against banana fusarium wilt.The specific research results are as follows:1 under different p H gradients(the p H values were 4.2,5.2,6.2,72,and 8.2,respectively),the experimental results of the plate bacteriostatic activity of zj6-6fermentation broth and FOC4 showed that:(1)when the p H value was 4.2,zj6-6 could hardly carry out normal growth and reproduction,and the obtained fermentation broth had no inhibitory effect on FOC4.(2)The bacteriostatic effects of the other p H gradient culture conditions were:6.2>5.2>7.2>8.2.(3)The bacteriostasis rate was 31.92%under the p H value of 6.2.The real-time fluorescence quantitative PCR was used to determine the expressions of three biocontrol genes of ZJ6-6,including srf AB,fen D and itu D under different p H values.The results showed that:(1)the three biocontrol genes had significantly different expressions at the same time point and under different p H values.(2)the bio-defensive genes srf AB and fen D for maximum value within about 16 h under different p H values.Itu D reached its maximum value after 24 h of culture.(3)at p H 6.2,the expression levels of the three biocontrol genes were all higher at different time points.2 tablet active detection of different temperature gradient(temperature 25℃,28℃,31℃,34℃and 37℃),under the condition of ZJ6-6 in the fermented liquid of FOC4mycelium growth of antibacterial activity,the results showed that:(1)under different temperature conditions,the inhibition effect is different,when the temperature of 31℃,bacteriostatic effect bacteriostatic rate(26.77%),the best.(2)in the temperature of 37℃,the bacteriostasis is low,the other three effect of temperature gradient difference was not significant.Fermented liquid under the conditions of different temperature on FOC4 spore germination inhibition experiment results show that:under the condition of different temperatures,ZJ6-6 fermented liquid of FOC4 spore germination inhibition rate and plate bacteriostatic activity of the experimental results are basically identical,and the temperature of 31℃under the condition of the spore germination inhibition rate of75.31%.3 soil colonization experiment results showed that:(1)the colonization amount of Rif ZJ6-6 in field soil of different treatments was successively shown as:unsterilized+plant>sterilized>unsterilized;Among them,the amount of colonization in the unsterilized+plant treatment and the sterilized treatment maintained a dynamic balance between 1.82×10~5 cfu/m L and 1.21×10~5 cfu/m L,respectively.However,the content in the unsterilized treatment showed a decreasing trend,and the content was at the level of 5×10~4 cfu/m L.(2)the amount of rifzj6-6 colonization in different substrate soils is also significantly different,its colonization effect in the soil of the sterilization treatment is the best,up to 7.20×10~5cfu/m L,the first rise and then decline,and then maintain a relatively stable dynamic balance;In the other two treated soils,the content was lower than that of the sterilization treatment,which also increased first and then decreased slightly,and then maintained a relative dynamic balance at the level of 2×10~5 cfu/g.4.the results of pot colonization experiment showed that:(1)the contents of roots and corms of Rif ZJ6-6 in resistant varieties were maintained at 10~2 cfu/g,but the colonization of Rif ZJ6-6 was not detected in the pseudostem.(2)the colonization ability of Rif ZJ6-6 in different parts of different varieties was shown as follows:the colonization ability of rhizoma xanthophylla in south China was better than that in the susceptible variety rhizoma xanthophylla in south China.5 the results of potted growth promotion experiment showed that the stem diameter,plant height,fresh(dry)weight,chlorophyll and other plant growth related traits of disease-resistant and susceptible banana varieties were significantly increased compared with that of the sterile water control group,revealing that Rif ZJ6-6 had a significant growth promotion effect on bananas.In addition,the growth promoting effect of the banana resistant variety nantianhuang was better than that of the susceptible variety Brazil banana.6 pot experiment results showed that:(1)when Rif ZJ6-6 and FOC4 were inoculated at the same time,there was no significant control effect on resistant and susceptible banana varieties.After 14 days of inoculation,the relative control effect was 45.48%and 33.19%,respectively.After 28 days of inoculation,the relative efficacy was 20.44%and 18.67%,respectively.(2)for the disease-resistant variety nantianhuang,after inoculation with Rif ZJ6-6 for 3 days and then inoculation with FOC4 at different concentrations,the relative control effect was significantly improved,and the lower the concentration of pathogen inoculation,the better the control effect.In conclusion,inoculation with biocontrol bacteria for 3 days before inoculation with pathogenic bacteria can effectively improve the control effect of ZJ6-6 against banana fusarium wilt. |
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