Aspergillus flavus growth and aflatoxin production as influenced by total lipid content during growth and development of cottonseed

Authors: Rajasekaran, Kanniah - Rajah; Ford, Gregory; Sethumadhavan, Kandan; Carter-Wientjes, Carol; Bland, John; Cao, Heping; Bhatnagar, Deepak

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2016
Publication Date: 11/19/2016
Citation: Rajasekaran, K., Ford, G., Sethumadhavan, K., Carter Wientjes, C., Bland, J., Cao, H., Bhatnagar, D. 2016. Aspergillus flavus growth and aflatoxin production as influenced by total lipid content during growth and development of cottonseed. Journal of Crop Improvement. 31(1):91-99. https://doi.org/10.1080/15427528.2016.1263811.
DOI: https://doi.org/10.1080/15427528.2016.1263811

Interpretive Summary: The fungus Aspergillus flavus infects several food and feed crops such as corn, cotton, peanuts and tree nut crops and produces carcinogenic aflatoxins. These susceptible crops contain rich reserves of lipids and fatty acids. In cottonseed, one of the rich proteinaceous animal feed, the nature of relationship between lipids and the ability of the fungus to infect and produce aflatoxins has been addressed in several in vitro studies using mature cottonseed. In this study, we have tracked lipid accumulation in developing cottonseed (15-35 days post anthesis, dpa) and also the ability of the fungus to grow and produce aflatoxins in planta. The toxigenic strain Af-70 GFP and the isogenic, non-toxigenic strain SRRC 1500 did not differ much with regard to infection, colonization of cottonseed; however, the non-toxigenic strain did not produce aflatoxin at all stages of cottonseed development. On the other hand, the toxigenic strain Af-70 GFP produced copious amounts of aflatoxin and it coincided very closely with the increasing levels of lipids, especially in mature cottonseed (30-35 dpa). Fungal growth, as quantified by the GFP expression in the fungus, was also highly correlated with the toxin production. This study makes it possible to understand the relationship between lipids accumulation and Aspergillus infection, growth followed by aflatoxin contamination, a key prerequisite for devising control measures by breeding or biotechnology.

Technical Abstract: Aspergillus flavus infects several food and feed crops such as corn, cotton, peanuts and tree nut crops and contaminates the seed with carcinogenic aflatoxins. These susceptible crops contain rich reserves of lipids and fatty acids. The nature of relationship between lipids and the ability of the fungus to infect and produce aflatoxins in mature cottonseed, a protein-rich animal feed, has been addressed previously. In this study, we tracked lipid accumulation in developing cottonseed (15-35 days post anthesis, dpa) and also the ability of a toxigenic strain and an isogenic non-toxigenic strain to grow and produce aflatoxins in planta. The aflatoxigenic strain Af-70 GFP and the isogenic, non-toxigenic strain SRRC 1500 did not differ much in infection, colonization of cottonseed. The non-toxigenic strain did not produce aflatoxin at all stages of cottonseed development whereas, the toxigenic strain Af-70 GFP produced copious amounts of aflatoxin and it coincided with the increasing levels of lipids, especially in mature cottonseed (30-35 dpa). Fungal growth, as quantified by the GFP expression in the fungus, was highly correlated with the toxin production.