Analyses of Genetic Diversity and Aflatoxin in Arachis hypogaea L. of Kenya and Malawi

Peanut breeding programs often focus on yields and disease control overlooking aflatoxin (AF) contamination. This study sought to assess genetic variation in 10 peanut varieties using both molecular markers and aflatoxin accumulation levels. Random amplified polymorphic DNA (RAPDs) analysis and Ultrahigh-Performance Liquid Chromatography (UHPLC) were used respectively, in peanut varieties from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Malawi and varieties sourced from local markets in Kenya. Eleven primers used generated a total of 63 scorable bands, revealing 39 polymorphic loci across the 10 varieties. Percentage of polymorphic loci among Malawian varieties was higher (74.4%) than Kenya varieties (46.2%). Analysis of molecular variance (AMOVA) was 24.1% and 75.9% within and among groups respectively defined based on PCoA. Expected heterozygosity (HE) was 0.18 for local varieties and 0.30 for Malawian varieties with the Shannon diversity index (SDI) that followed the same trend (0.26 and 0.44, respectively). Variety ‘CG12’ clustered alone thus the most divergent from all other varieties and had the lowest total aflatoxins (1.36 µg/kg). No significant relationships occurred between aflatoxin levels in the varieties and genetic variation (p>0.05). Variety ‘12991’ showed the lowest AFB2(0.15µg/kg), ‘Local 5’ and ‘Local 3’ displayed the lowest AFG1(1.28 µg/kg), and AFG2(0.34µg/kg) levels respectively. The most toxic aflatoxin(AFB1) was recorded in 40% of varieties and limits >5µg/kg which is unacceptable by Kenya Bureau of Standards. Although more in-depth genetic and multi-environmental confirmation field trials are necessary, our data suggests this heritable variation that might be exploited in future breeding programs.