Background: Aflatoxins are highly carcinogenic secondary metabolites produced by Aspergillus flavus and A. parasiticus when they infect agricultural crops such as peanut and maize. Previous gene profiling studies by EST and microarray strategies under A. flavus infected conditions in field peanut, identified 22 up-regulated genes resistant to A. flavus infection in peanut. Methods: For studying the mechanism of plant/fungal interaction, specifically the mode of inhibition to fungal growth and/or aflatoxin formation in A. flavus, a total of 10 peanut genes and 8 fungal genes directly involved in aflatoxin formation were targeted for this study. The two peanut lines showing resistant and susceptible to fungal infection were inoculated with A. flavus NRRL 3357. Fungal growth was measured visually and aflatoxin formation was assessed by HPLC. The expression levels of selected peanut genes and aflatoxin pathway gene were detected by RT-PCR and real-time PCR from RNA samples collected from 1 to 7 day cultures after inoculation. Results: Preliminary results indicated that the expression of aflatoxin pathway genes in A. flavus was significantly inhibited. On plant side, three resistant genes in peanut were identified. Conclusion:We have demonstrated for the first time that genes from resistant peanut line showing inhibition to both fungal growth and aflatoxin formation. The regulatory mechanism of inhibition on aflatoxin formation in fungus involved in those genes is under further investigation.
Full conference title:
- ASM 112th (2012)