Fumonisin and ochratoxin-producing strains of section are associated with onion ( L.) bulbs sold in markets in southwest Nigeria.

INTRODUCTION

Onion bulbs are edible, nutritious vegetables and spices. In Nigeria, mass propagation of onion seedlings is limited due to infection of the onion bulbs by section , especially strains. Mycotoxin-producing strains are detrimental to public health. Hence, this study was undertaken to screen the locally sourced onion bulbs for fumonisin B (FB) [Multiplex A: (374 bp), (272 bp), (168 bp), and (479 bp) and Multiplex B: (452 bp), (238 bp), (173 bp), and (321 bp)] and ochratoxin A [OTA; (776 bp)] biosynthetic genes.

METHODS

Thus, 100 onion bulbs were collected from four different local markets (Dugbe, Agbowo, Sasa, and Omi). The surface of each bulb was disinfected, and after incubation, isolates of were detected. isolates were cultured on potato dextrose agar. Genomic DNA was extracted from isolates of . Multiplex PCR confirmed the presence and absence of FB () and OTA () biosynthetic genes.

RESULTS AND DISCUSSION

A total of 200 isolates of were isolated from the onion bulbs, and 22 (11%) isolates amplified at least two genes, while three (1.5%) amplified the gene. All isolates were positive for and . The highest/lowest percentage of the location/isolates of and was Agbowo/Omi with 32.0%/2.1% and Dugbe/Agbowo with 6.7%/2.3%, respectively. Hence, the use of multiplex PCR to detect FB and OTA biosynthetic genes in the isolated strains from the locally sourced onion bulbs will assist onion growers in the mass production of healthy onion seedlings with export potential and quality. Early detection of FB and OTA biosynthetic genes is important to predict possible mycotoxin-producing . section in onion bulbs.