A Global Screening Assay to Select for Maize Phenotypes with a High Tolerance or Resistance to Fusarium verticillioides (Sacc.) Nirenberg Rots

Shamir Gabriel Román,Francisco Roberto Quiroz-Figueroa,Miguel Villalobos,Eusebio Nava-Pérez,Rupesh Kumar Singh,Eliel Ruíz-May,Jesús Quiroz-Chávez,Vianey Urías-Gutiérrez,Lav Sharma

doi:10.3390/agronomy10121990

Shamir Gabriel Román, Francisco Roberto Quiroz-Figueroa + Show 7 more

Open Access

https://doi.org/10.3390/agronomy10121990

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Abstract

Fusarium verticillioides (Sacc.) Nirenberg (Fv) causes rots in maize around the world and produces mycotoxins that contaminate grains, making this species a significant health concern for both animals and humans. One of the best approaches to address rots is to identify highly tolerant or resistant genotypes that can be used for genetic improvement. The aim of the study was to evaluate dose-response assays to tolerance or resistance for Fv rots throughout the maize life cycle. These tests assessed the effects of Fv during post-germination development and the seedling (V2) stage by seed infection, the plantlet (V4) stage by substrate infection, and in the reproductive phase in maize stalks (R2 stage) and ears (R6 stage) by R1 stage inoculation. In all assays, the doses were effective at distinguishing contrasting phenotypes. Severity, root fresh weight, and aerial length were the most informative parameters at the V2 and V4 stages. Evaluation of the stalk necrosis area between and within the internodes of susceptible genotypes revealed significant differences among doses, and a positive correlation between necrosis and conidia concentration was observed in internodes. Injecting eight million conidia in the ear was sufficient for selecting different phenotypes. A total of 85% of the genotypes conserved their same capacity to respond to Fv infection throughout the maize life cycle, so that screening at the early vegetative stage (e.g., V2) could be useful for distinguishing contrasting phenotypes in the reproductive stage. Implementing these screening assays in a maize breeding program could be valuable for classifying the degrees of resilience of maize germplasms to Fv rots. This global screening has the potential to be employed to select against other Fusarium species.

Highlights

Maize (Zea mays L.) is one of the most important crops worldwide
In order to identify the contrasting maize phenotypes in response to the Fusarium verticillioides (Sacc.) Nirenberg (Fv) effect on post-germinative growth (VE stage), genotypes were challenged with Fv in rolled paper assays for four days
Of the grains were damaged (Figure 5a), whereas the IL1 genotype had a very low percent of affection. These results suggest that our protocol and the doses employed can efficiently discriminate between resistant and susceptible genotypes, and that the conidia concentration presented here can be considered for screening and selecting against Fv ear rot

Summary

Introduction

Maize (Zea mays L.) is one of the most important crops worldwide. Due to its high demand as an important food resource for humans and animals, and as a raw material for use in industry and biofuels [1], maize production is increasing at a faster rate than other cereals [1,2]. Maize mono-cropping and its genetic homogeneity (due to a narrow genetic pool of commercial hybrids used extensively in agriculture) enable the establishment of pathogens [3,4]. The amount of toxins found in grains used for food production or feeding must; be taken into consideration, since they are harmful to both animal [10,11] and human health [12,13,14,15]

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