Response of wild Avena species to fungal infection of grain

Sixty-six accessions belonging to Avena species (A. atlantica, A. canariensis, A. clauda, A. damascena, A. hirtula, A. longiglumis, A. wiestii, A. agadiriana, A. barbata, A. vaviloviana, A. insularis, A. magna, A. murphyi, A. fatua, A. ludoviciana, A. occidentalis, A. sterilis, A. sativa, and A. byzantina) obtained from the N. I. Vavilov Institute of Plant Genetic Resources (VIR) were tested for the infection of grain by Alternaria and Cladosporium at the genus level and by a group of trichothecene-producing Fusarium fungi. Real-time PCR was performed to quantify fungal abundance and ELISA was performed for mycotoxin analysis in grain. The average amounts of all tested fungi in tetraploid Avena species were higher than those in diploid and hexaploid species. Low amounts of deoxynivalenol (DON) were detected in seven hexaploid genotypes (A. sterilis, A. byzantina, A. sativa, and A. fatua) and one diploid genotype (A. wiestii). The relationship between some morphological traits (1000-grain weight, percent of husk, trichome density, and plant height) of Avena species and grain infection by fungi and mycotoxins was investigated. Alternaria and Cladosporium fungi could not penetrate the husk. A highly negative correlation of the amounts of their DNA with the proportions of husk in grain as well as with trichome density was found. In contrast, a significant positive correlation between the amount of Fusarium DNA and these traits was found. A strong negative correlation between plant height and DNA of the analyzed fungi was found. The oats least infected by Alternaria, Cladosporium, and Fusarium fungi and containing low amounts of DON were accessions of the hexaploids A. byzantina, A. fatua, A. sativa, A. sterilis, and the diploid A. wiestii.