Global Transcriptome Profiling Identified Transcription Factors, Biological Process, and Associated Pathways for Pre-Harvest Aflatoxin Contamination in Groundnut.

Pooja Soni,Rajeev K Varshney,Hari K Sudini,Prasad Bajaj,Priya Tolani,Prashant Singam,Sarita Pandey,Baozhu Guo,Manish K Pandey,Arun K Pandey,Jake C Fountain,Spurthi N Nayak

doi:10.3390/jof7060413

Abstract

Pre-harvest aflatoxin contamination (PAC) in groundnut is a serious quality concern globally, and drought stress before harvest further exacerbate its intensity, leading to the deterioration of produce quality. Understanding the host–pathogen interaction and identifying the candidate genes responsible for resistance to PAC will provide insights into the defense mechanism of the groundnut. In this context, about 971.63 million reads have been generated from 16 RNA samples under controlled and Aspergillus flavus infected conditions, from one susceptible and seven resistant genotypes. The RNA-seq analysis identified 45,336 genome-wide transcripts under control and infected conditions. This study identified 57 transcription factor (TF) families with major contributions from 6570 genes coding for bHLH (719), MYB-related (479), NAC (437), FAR1 family protein (320), and a few other families. In the host (groundnut), defense-related genes such as senescence-associated proteins, resveratrol synthase, seed linoleate, pathogenesis-related proteins, peroxidases, glutathione-S-transferases, chalcone synthase, ABA-responsive gene, and chitinases were found to be differentially expressed among resistant genotypes as compared to susceptible genotypes. This study also indicated the vital role of ABA-responsive ABR17, which co-regulates the genes of ABA responsive elements during drought stress, while providing resistance against A. flavus infection. It belongs to the PR-10 class and is also present in several plant–pathogen interactions.

Highlights

Aflatoxins are strong cancer-causing and teratogenic mycotoxins produced in crops such as groundnut, maize, cottonseed, chilies, and tree nuts upon infection by Aspergillus flavus and A. parasiticus
The molecular mechanism correlated with the pre-harvest aflatoxin contamination (PAC) mechanism is not yet clearly welldefined and the availability of high-quality reference genomes provides a great opportunity for improving our current understanding
A. flavus infection and aflatoxin production are reported to be controlled by a combination of factors like reactive oxygen species (ROS), LOX genes, carbohydrate and fatty acid biosynthesis pathway factors, defense proteins like pathogenesis related etc. [47,48,49,50,51]

Summary

Introduction

Aflatoxins are strong cancer-causing and teratogenic mycotoxins produced in crops such as groundnut, maize, cottonseed, chilies, and tree nuts upon infection by Aspergillus flavus and A. parasiticus. Aflatoxin exposure can have significant negative impacts on human health. It is considered as a growth development retardant in the young [3] and an immune suppressor [4], contributing to susceptibility to AIDS [5]. Aflatoxin B1 (AFB1 ) produced by the A. flavus and A. parasiticus is believed to be the essential driver of liver disease, alongside ongoing hepatitis B and C infections [6] and intense aflatoxicosis [7,8]. The PAC is a vital segment of aflatoxin which, if ignored, increases in intensity during post-harvest operations such as packing, transportation and storage [11,12,13]

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