Peanuts that keep aflatoxin at bay: a threshold that matters

Abstract

SummaryAflatoxin contamination in peanuts poses major challenges for vulnerable populations of sub‐Saharan Africa and South Asia. Developing peanut varieties to combat preharvest Aspergillus flavus infection and resulting aflatoxin contamination has thus far remained a major challenge, confounded by highly complex peanut–Aspergilli pathosystem. Our study reports achieving a high level of resistance in peanut by overexpressing (OE) antifungal plant defensins MsDef1 and MtDef4.2, and through host‐induced gene silencing (HIGS) of aflM and aflP genes from the aflatoxin biosynthetic pathway. While the former improves genetic resistance to A. flavus infection, the latter inhibits aflatoxin production in the event of infection providing durable resistance against different Aspergillus flavus morphotypes and negligible aflatoxin content in several peanut events/lines well. A strong positive correlation was observed between aflatoxin accumulation and decline in transcription of the aflatoxin biosynthetic pathway genes in both OE‐Def and HIGS lines. Transcriptomic signatures in the resistant lines revealed key mechanisms such as regulation of aflatoxin synthesis, its packaging and export control, besides the role of reactive oxygen species‐scavenging enzymes that render enhanced protection in the OE and HIGS lines. This is the first study to demonstrate highly effective biotechnological strategies for successfully generating peanuts that are near‐immune to aflatoxin contamination, offering a panacea for serious food safety, health and trade issues in the semi‐arid regions.

Scaling-Up the Impact of Aflatoxin Research in Africa. The Role of Social Sciences

“…Researchers from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) have successfully applied this technique to peanuts. The question is whether this approach can also significantly reduce aflatoxin contamination in other crops and not just in groundnut [41]. …”

Functional Biology and Molecular Mechanisms of Host-Pathogen Interactions for Aflatoxin Contamination in Groundnut (Arachis hypogaea L.) and Maize (Zea mays L.)

“…Using multiple approaches in groundnut and maize have led to the identification of several moderate/low/high resistant lines for A. flavus infection and reduced aflatoxin contamination. These advances have facilitated the development of aflatoxinresistant transgenic groundnut (Sharma et al, 2018) and maize (Thakare et al, 2017); and it is expected that in the coming years, farmers may have access to superior and aflatoxin-resistant varieties. However, the release of transgenic cultivars is dependent on their acceptance by regulators in the target countries.…”

“…In groundnut, very few reports on transgenic approaches are available substantiating the importance of host genes like PR and defensin (Xie et al, 2013;Arias et al, 2015). A study (Sharma et al, 2018) has shown that the overexpression of Medicago defensin genes-MsDef1 and MtDef4.2 reduced Aspergillus infection as well as AP in susceptible groundnut variety JL 24. The study also demonstrated a host-induced gene silencing (HIGS) mediated silencing of aflatoxin biosynthetic pathway regulatory genes aflM and aflP to inhibit AP.…”

Past, Present and Future Perspectives on Groundnut Breeding in Burkina Faso

“…In such conditions, genetic transformation presents great potential in groundnut improvement to utilize genes from other species [44,69,140,141]. Likewise, the difficulties of plant regeneration by tissue culture techniques and selection of transgenic events [141][142][143] are being overcome by recent advances in groundnut transformation process [144]. To date, at least a dozen of successful groundnut transformations have been reported in the literature [68].…”