Gene Expression Profile Of The ABC Transporters In The Tolerance Of Gliocladium Roseum To The Antibiotic Metabolites Of Pseudomonas Choloeaphtis

Gliocladium roseum strain IK726 and Pseudomonas choloeaphtis strain MA342 are two promising biocontrol microbes which both has various biocontrol mechanisms to control many seed and soil-borne plant diseases.Because a potential additive effect may exist between these two biocontrol microbes,we expected to get a more competitive biocontrol with a mixture of IK726 and MA342.But considerable uncertainty existed in the tolerance of IK726 against a wide range of antifungal metabolites of MA342.Dual culture assay and mycelial dry weight measurement were used to demonstrate the influence of antifungal metabolites of MA342 to the growth rate and biomass production of IK726.Furthermore,13 candidate genes were selected within the ABC transporters superfamily which were possibly involved in the antibiotic resistance of IK726.The expression patterns of putative ABC transporter genes in IK726 were monitored using quantitative reverse transcription PCR during the treatment of the culture filtrate of MA342.The results are as follows:1)We got an exciting result that IK726 displayed a high level of resistance to the antifungal metabolites of MA342.Neither living MA342 or its culture filtrate can suppress the mycelium growth of IK726.We guess after long-term evolution that IK726 has already developed a mature tolerant mechanism to cope the exogenous toxics.2)The transcript levels of putative multidrug resistance(MDR)gene(ABC4267)and mitochondrial peptide transporter gene(ABC4987)were relatively increased during 2-6 hours of MA342 culture filtrate treated,especially ABC4267 was over 10 fold increased compared to the non-treated control,but after 24 hours treated these two gene expressions were decreased to normal level as non-culture filtrate treated control.Siderophore transporter gene(ABC3069)of IK726 in all treated groups showed a higher expression throughout the 24 hours.The expression levels of pheromone transporter gene(ABC2419)and pleiotropic drug resistance(PDR)gene(ABC3525)of treated IK726 were detected only increased within 2hours.Higher expressions of secondary metabolite transpoter genes(ABC592,ABC3918),MDR gene(ABC3260)and PDR gene(ABC4345)of treated IK726 were only detected after 6hours and then decreased to normal level.Treated with MA342 filtrate has no influence to the expression levels of putative pheromone transporter gene(ABC2210),secondary metabolite transporter gene(ABC3433,ABC2700)and PDR gene(ABC3189).