Induction of tolerance to Fusarium head blight

Abstract

Fusarium head blight (FHB), caused by Fusarium graminerarum, is a very important wheat disease causing remarkable economical damage in Argentina. Because only a few resistance sources are available, we tested synthetic hexaploids as a donor for FHB resistance several years ago. Several lines showed induced resistance against FHB after a phytohormone treatment. In this study, two novel lines (L and M) and a comercial cultivar (ACA 315) were tested in twodifferent localities (La Plata and Tres Arroyos) during three years. A split-plot design was used in order to compare the responses to the following hormone treatments: salicilic acid, jasmonic acid, giberellic acid, a solution with a strain of Pseudomonas fluorescens, or water (control), which were sprayed at anthesis. Twenty-four hours later, half of the plots of each pretreatment of each genotype were inoculated. Spikes were harvested manually, and the number of total grain, damaged kernels, and 1,000-kernel weight were recorded. Pretreatment with gibeerellic acid increased the total grain in lines L, M, and ACA315 with and without inoculation with F. graminearum compared to the controls and the rest of the treatments. Jasmonic acid induced fewer damaged kernels in lines L and M. The commercial cultivar did not show any differences between treatments. The treatment with P. fluorescens induced the highest levels of tolerance in both experimental lines with the lower values of damaged kernels and with a higher 1,000-kernel weight. These results were similar in both localities in the last two years. The elicitation of SAR in the experimental lines increased the tolerance to FHB.