Abstract
Aflatoxin contamination is a global menace that adversely affects food crops and human health. Peanut seed coat is the outer layer protecting the cotyledon both at pre- and post-harvest stages from biotic and abiotic stresses. The aim of the present study is to investigate the role of seed coat against A. flavus infection. In-vitro seed colonization (IVSC) with and without seed coat showed that the seed coat acts as a physical barrier, and the developmental series of peanut seed coat showed the formation of a robust multilayered protective seed coat. Radial growth bioassay revealed that both insoluble and soluble seed coat extracts from 55-437 line (resistant) showed higher A. flavus inhibition compared to TMV-2 line (susceptible). Further analysis of seed coat biochemicals showed that hydroxycinnamic and hydroxybenzoic acid derivatives are the predominant phenolic compounds, and addition of these compounds to the media inhibited A. flavus growth. Gene expression analysis showed that genes involved in lignin monomer, proanthocyanidin, and flavonoid biosynthesis are highly abundant in 55-437 compared to TMV-2 seed coats. Overall, the present study showed that the seed coat acts as a physical and biochemical barrier against A. flavus infection and its potential use in mitigating the aflatoxin contamination.
Highlights
IntroductionMycotoxins are produced by Aspergillus, Fusarium, and Penicillium species as a defense response as well as in response to environmental changes [1]
The A. flavus strain used was isolated from infected peanut seeds and characterized for the experiments in the present study
The Polymerase Chain Reaction (PCR) data showed that A. flavus isolates 1, 2, and 3 contain all the tested toxigenic biosynthetic genes (Table 5)
Summary
Mycotoxins are produced by Aspergillus, Fusarium, and Penicillium species as a defense response as well as in response to environmental changes [1]. Are produced by Aspergillus flavus and A. parasiticus, and have been considered as the most potent mycotoxins, especially aflatoxin B1 (AFB1 ). AFB1 has been recognized as a class. I human carcinogen by the International Agency for Research on Cancer [2]. Aflatoxin poses significant health problems in humans, such as liver cancer, growth impairment in children, and acute aflatoxicosis in developing countries [3]. The average dietary exposure to aflatoxin is generally below 1 ng/kg body weight per day, while those of sub-Saharan nations in Africa are above 100 ng/kg body weight per day [4]
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