Genetic transformation to mitigate drought and aflatoxin-related losses in peanut

Authors: FOUNTAIN, J - University Of Georgia; KEMERAIT, R - University Of Georgia; CHU, Y - University Of Georgia; OZIAS-AKINS, P - University Of Georgia; CHEN, Z - Louisiana State University; WANG, K - Iowa State University; YANG, Y - Pennsylvania State University; Guo, Baozhu

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The mitigation of aflatoxin and drought stress related losses and food safety risks are priorities for the peanut research community. The development of novel technologies in combination with recent advances in peanut genomics allow for the deployment of genetic transformation and genome editing to address this issue. Previously, we have found that drought tolerance and aflatoxin resistance are correlated with reduced accumulation of reactive oxygen species (ROS) in peanut and corn. It was hypothesized that modifying the accumulation of antioxidant enzymes in these plants may result in reduced aflatoxin accumulation and increased drought tolerance. To test this hypothesis, we have used biolistic transformation to independently overexpress three antioxidant genes, AhAPX1, AhCAT1, and AhSOD1 in the cultivar Georgia Green. Conversely, we have engineered a novel polycistronic guide-RNA (gRNA) into the CRISPR-Cas9 cassette for genome editing to silence the expression of an isoform of AhCAT1. These approaches have resulted in the performance of six bombardments per construct/gene. Following regeneration and root induction, 27, 40, and 28 potentially transgenic T0 plants have been generated representing 9, 11, and 6 independent transgenic events for overexpression of AhAPX1, AhCAT1, and AhSOD1, respectively. Regeneration of CRISPR-Cas9 plants is currently in progress. Genotypic and phenotypic evaluation is currently underway with both PCR and enhanced green fluorescent protein (eGFP) expression. Using eGFP expression as an initial screen in young root and foliar tissues, 37.0%, 47.5%, and 42.9% of regenerated plants (43.2% overall) for AhAPX1, AhCAT1, and AhSOD1, respectively, showed positive eGFP expression. This may indicate that these overexpression constructs are inserted into expressible regions of the peanut genome and warrant further evaluation. Effects of these genome modifications on antioxidant gene expression and ROS accumulation will be discussed along with the potential effects on aflatoxin contamination and drought tolerance.