Effect of Fumonisin B1 on Transcriptional Profiles and Biochemical Signatures in Resistant and Susceptible Maize Shoots

Fumonisin B1 (FB1) is the most harmful toxin, due to its incidence and high concentrations in maize, along with its toxicity to humans and animals. To investigate possible mechanisms of FB1 phytotoxicity, an RNA-Sequencing based transcriptome analysis was carried out at 3 h after FB1 treatment in the shoots of the CO433 maize line resistant to Fusarium verticillioides. One thousand four hundred and fifty-nine differentially expressed genes were identified, 13.9% of them playing a role in defense and cell rescue functional classes. The study of the transcriptional changes was extended to the CO389 genotype susceptible to F. verticillioides at 3 and 48 h after exposure to FB1 for a subset of thirteen genes involved in the antioxidant metabolism, mycotoxin detoxification, cell death regulation, hormone signaling, and ubiquitination. Moreover, antioxidant enzymes and compounds were monitored in the same plant material. Defense responses appeared promptly activated in the shoots of the resistant genotype; particularly, at 3 h, the accumulation of most transcripts and enzymes protecting from oxidative stress and involved in the toxicity response processes as well as the ascorbate content were enhanced, underlining an earlier and higher attitude in this background to counteract the phytotoxic action of FB1. In contrast, in the susceptible line, the expression of the majority of genes along with catalase, phenolics and ascorbate levels increased at later treatment time, conferring a lower readiness in response to the mycotoxin. This work provides useful sources of markers for the development of successful disease management strategies in maize.