Quantification For Abundance Of Banana Wilt Pathogen Foc4 In Banana Plantation Soil

The incidence of the Fusarium wilt of banana is closely associated with the number of FOC4 in soi.In order to accurately detect the amount of FOC4 in soil before planting banana,in this study,the FOC4 specific gene fragment cloned in our laboratory was used as the standard linear fragment,which could design of specific fluorescent quantitative primers.On the basis of this,the fluorescence quantitative standard curve was established with standard linear fragment as template,and standard soil samples with FOC4 spore concentration gradient was configured without non-FOC4 soil.The total soil DNA was extracted with the Mo Bio soil DNA purification Kit,and it also extracted from standard soil samples with FOC4 spore concentration(1.66x103～1.66×108 copies/μL)gradient,which was as template to detect the quantity of foc4 in each standard soil sample by real-time fluorescence quantitative RCR.Using the results of copy number of linear fragment gene of FOC4 in standard soil sample and the ratio of theoretical copy number to the 100%extraction rate as the extraction rate of FOC4 genome in the standard soil sample.An accurate fluorescence quantitative PCR method was set up to determine the content of FOC4 in soil according to the calibration value of the relative DNA yield,which can detect up to 300 spores/g soil.We used this method in the tests on soil samples from healthy and diseased fields,and obtained an obvious distinction.FOC4 content could accurately reflect the wilt incidence among less than 1%,1%-5%,5%-20%,and 20%.Disease rate was increased with the content of FOC4 in soil samples,showing a less than 1%rate when the quantity of FOC4 was below 7×103,and a remarkably high disease incidence,when FOC4 reached up 2×104.At 14 d after treatment,both dazomet and lime exhibited significantly reduction on the content of FOC4 in soil samples from field with above 50%wilt incidence,though it was not enough to reach below 1%or 1%-5%incidence.In the examination of banana field with a 1%-5%wilt incidence in three-month integrative management,Compound microbial fertilizer and organic fertilizer were observed with an inhibition on the quantity of FOC4 when applied in soils treated with dazomet or lime in advance.In contrast,common chemical fertilizer was found promote FOC4 in the dazomet or lime treated soils.This study can be helpful for the accurate detection of foc4 content in soil and the prevention and control of the Fusarium wilt of banana.