Endophytes isolated from maize Lombard landraces: new perspectives for the control of Fusarium verticillioides

Maize is one of the most important crops in our country. However, in the past years yields have gradually decreased due to reduced cultivated areas and climate change. GEMMA project aims to study the endophytic bacterial community of landraces and their relationship with Fusarium verticillioides, one of the most widespread toxicogenic fungal pathogens in Lombardy region. Recent studies show how endophytes have abilities to inhibit the development of pathogens. Over the past three years four traditional landraces (Nero Spinoso Valcamonica, Spinato Gandino, Rostrato Rosso Rovetta, Fiorine Clusone, preserved at CREA Bergamo Genebank) and a pure line (B73) were grown in different locations (Landriano, Bergamo, Verderio, Carvico) with low-input farming techniques. Embryo of seeds harvested in 2019 allowed the isolation of 96 bacterial strains, mostly Firmicutes. In vitro antifungal assays against F. verticillioides allowed the selection of 12 strains with inhibition percentage higher than 50% for in vivo test. Only 2 isolates (Bacillus and Psychrobacillus) significantly reduced fungal infection in vivo. In 2021, experimental inoculations with F. verticillioides conidia were carried out in field during flowering. Values of infected seeds/ear and % infected area/ear show that Spinato di Gandino is the most susceptible variety while Nero Spinoso is confirmed as being the least susceptible. The study of microbiota and resistance traits from landraces shows potential for future organic maize production where biocontrol agents and resistant genotypes can contribute to a better, and more sustainable, response to stresses that will allow a higher maize yield even in the scenario of climate change.