Figure 6

Illustration of cross-talk between groundnut (Arachis hypogaea) and fungus (Aspergillus flavus) during in-vitro seed colonization. The genes/components illustrated represent the defense responsive molecules identified from groundnut-A. flavus interaction during in-vitro seed colonization studies. The components marked within the green rectangular box (with green arrows) are those induced in groundnut and those which are in light blue rectangular box (blue arrows) are the components induced in pathogen in compatible reaction through mixed transcriptome analysis. The components represented in dark blue boxes have important role in host-pathogen interaction in this study. Briefly, the pathogenesis initiation occurs at plant cell wall where NBS-LRR, elicitors and oxylipins have important role in host-pathogen interactions. JA and SA signaling pathways mediated by transcription factors like WRKY, NAC, MYB and ERFs play important role in plant defense. During the process of defense the phytoalexins like resveratrol synthase/stillbene synthase, PR proteins, LOX, chalcone synthase and PAL were expressed. Basal resistance works with the expression of senescence associated proteins that give hypersensitive response to combat the pathogen entry further. The chitinases, glucanases, PGIPs, PAL, PR proteins induce cell wall degradation of fungi during pathogen entry. Due to pathogen attack, there is oxidative burst in the plant cell that regulates the oxidation of fatty acids that in turn involved in signal transduction. Transcriptome analysis of fungus indicated that the RLKs, SNARE complex, elicitors and oxylipins play important role in plant recognition and infection. Most of these proteins are integral part of cell wall and membrane. Genes involved in fungal growth, aflatoxin synthesis and transport were highly expressed in Aspergillus. Abbreviations: ROS- reactive oxygen species; SOD-superoxide dismutase; PR-pathogenesisrelated proteins; HR-hypersensitive response; JA-Jasmonic acid; SA- Salicylic acid; SAR-Systemic acquired resistance; LOX-lipoxygenase; PAL- Phenylalanine ammonia-lyase; Transcription factors-NAC (NAM, ATAF1/2 and CUC2 domain proteins), ERF (Ethylene responsive factors); MAPK- Mitogen-activated protein kinases; SNARE- soluble N-ethylmaleimide sensitive factor attachment receptor; RLK- receptor-like kinase; cAMP- Cyclic adenosine monophosphate, OmtA- O-methyl transferase; AFB1-aflatoxin B1.