Identifying Cotton (Gossypium hirsutum L.) Genes Induced in Response to Aspergillus flavus Infection

Aflatoxins are dangerous and carcinogenic mycotoxins produced as secondary metabolites of Aspergillus flavus and Aspergillus parasiticus.   A. flavus is the primary causal agent of aflatoxin contamination of cottonseed.  Although there is a fairly good understanding of the aflatoxin biosynthetic pathway and pathway cluster genes, the complex interaction between the saprophytic Aspergillus and cotton plant (cottonseed, in particular) is poorly understood due to the unavailability of resistant cotton genotype(s).  Genetic engineering to prevent preharvest aflatoxin contamination warrants for identification of resistance associated genes in cotton.  Availability of several small-scale differential mRNA imaging techniques and gene expression analysis allows rapid progress for identification and understanding of gene function related to phenotype.  Our objective in this study was to identify differentially expressed genes (DEGs) in cottonseed and pericarp as a result of Aspergillus infection; and to this end we used an annealing control primer (ACP) system providing a suitable primer with annealing specificity, which specifically targets sequence hybridization to the template via a polydeoxyinosine poly (dI) linker. In this study, we isolated 44 DEGs in response to A. flavus infection, using ACP system. Different functional classification of the DEGs suggested a complex and multi-factorial plant-fungus interaction.  Eight DEGs, including transcription factors,  kinase, and downstream stress responsive genes, showed a tissue- and time-dependent differences in their expression.  The upregulated genes can be used as transgenes and/or functional markers for breeding aflatoxin-resistant cottonseed.