Insights on host-pathogen interaction between groundnut (Arachis hypogaea) and Aspergillus flavus

Abstract

Aflatoxin contamination, caused by fungal pathogen Aspergillus flavus, is the major quality and health problem delimiting the trade and consumption of groundnut (Arachis hypogaea L.) worldwide. Three types of aflatoxin resistance mechanisms namely, resistance to in-vitro seed colonization (IVSC), pre-harvest aflatoxin contamination (PAC) and aflatoxin production (AP) have been reported in groundnut. Transcriptome sequencing approach was used to study the differentially expressed genes that differ in-vitro seed colonization (IVSC) in resistant (J 11) and susceptible (JL 24) genotypes. A total of 1,344 million raw reads with an average of 84 million reads per sample were generated from 16 libraries from four different stages of fungal infection. A total of 737.75 and 770.83 million reads were mapped on the progenitor genomes- A subgenome (A. duranensis) and B subgenome (A. ipaensis) of cultivated groundnut (A. hypogaea), respectively. In groundnut, defense related genes like senescence associated proteins, resveratrol synthase, seed linoleate 9s-lipoxygenases (9s-LOX), pathogenesis related proteins, peroxidases, glutathione- S-transferases, chalcone synthase, defensin and chitinases were differentially expressed. In A. flavus, the genes involved in growth and development of fungus, aflatoxin biosynthesis, binding and transporter proteins were found to be induced in compatible interaction. In addition to IVSC resistance, we have also carried out transcriptome sequencing for PAC and AP resistance. In summary, this study will provide greater insights on the resistance mechanisms and discovery of candidate genes for all the three mechanisms that can further be used as expression markers in genomics-enabled aflatoxin resistance breeding