Aflatoxins (B1, B2, G1 and G2) are notorious for their potent carcinogenic property in animal and human beings. They are produced from Aspergillus flavus and A. parasiticus. Aflatoxin contamination of agricultural crops not only causes significant economical losses in the world, but results in serious health problem in developing countries such as liver carcinoma and aspergillosis in immunocompromised individuals. In order to decifer the mechanism of aflatoxin production and regulation, sequencing of A. flavus NRRL3357 has been completed. This fungus has a genome of about 36-Mb in size and contains 13,488 genes including the aflatoxin gene cluster. For functional elucidation of the mechanism of genetic regulation on aflatoxin production, we performed genome-wide RNA-Sequencing by SOLEXA technology to characterize the entire transcriptome (cDNA fragments) under aflatoxin conducive and non-conducive conditions obtained from Poly(A)-enriched total RNA samples: (i) extracted from fungal mycelium grown under PMS medium, 29 C, 24h, no toxin; (ii) grown under GMS medium, 29 C, 24h, make toxin; and (iii) grown under GMS medium, 37 C, 24h, no toxin. Two cDNA libraries from each treatment were sequenced using the Illumina (SOLEXA) short-read technology. Over 5 Million 100 nt reads were sequenced for each cDNA prep, which were combined to generate a powerful high resolution map of the A. flavus transcriptome. In addition, we used the RPKM analysis to determine transcript abundance in the 3 mRNA samples. The analysis detected expression in at least 50 % of the genes for each condition and contributed to our better understanding on genetic regulation of aflatoxin formation.
Full conference title:
110th General Meeting American Society for Microbiology
- ASM 110th (2010)