Host Genotype and Weather Effects on Fusarium Head Blight Severity and Mycotoxin Load in Spring Barley.

Felix Hoheneder,Katharina Hofer,Eva Maria Biehl,Jennifer Groth,Michael Rychlik,Johannes Petermeier,Michael Heß,Ralph Hückelhoven,Markus Herz

doi:10.3390/toxins14020125

Abstract

Epidemiology of Fusarium Head Blight (FHB) of spring barley is relatively little understood. In a five-year study, we assessed quantitative resistance to FHB in an assortment of 17 spring barley genotypes in the field in southern Germany. To this end, we used soil and spray inoculation of plants with F. culmorum and F. avenaceum. This increased disease pressure and provoked genotypic differentiation. To normalize effects of variable weather conditions across consecutive seasons, we used a disease ranking of the genotypes based on quantification of fungal DNA contents and multiple Fusarium toxins in harvested grain. Together, this allowed for assessment of stable quantitative FHB resistance of barley in several genotypes. Fungal DNA contents were positively associated with species-specific Fusarium toxins in single years and over several years in plots with soil inoculation. In those plots, plant height limited FHB; however, this was not observed after spray inoculation. A multiple linear regression model of recorded weather parameter and fungal DNA contents over five years identified time periods during the reproductive phase of barley, in which weather strongly influenced fungal colonization measured in mature barley grain. Environmental conditions before heading and late after anthesis showed strongest associations with F. culmorum DNA in all genotypes, whereas for F. avenaceum, this was less consistent where we observed weather-dependent associations, depending on the genotype. Based on this study, we discuss aspects of practical resistance breeding in barley relevant to improve quantitative resistance to FHB and associated mycotoxin contaminations.

Highlights

Barley is a relatively stress-resilient crop that can be grown even under unfavourable conditions
To balance variations in infection among single years and to rate Fusarium Head Blight (FHB) resistance based on fungal DNA contents in harvested grain, a year-wise ranking and a total mean rank (n = 5 years) for individual genotypes were calculated, resulting in a slightly different genotype order compared to the order by average DNA contents
Quantitative FHB resistance of barley is still little exploited and not fully understood. This may be due to a complex interaction among individual genotypes, multiple Fusarium species, and strong associations of the Fusarium epidemiology with environmental conditions

Summary

Introduction

Barley is a relatively stress-resilient crop that can be grown even under unfavourable conditions. It is mainly used as animal feed and, when it comes to spring barley, for producing malt for brewing and food industries. Malting barley is a relatively high-value crop with high demands regarding grain quality. Pests and pathogens are provoking losses in yield and quality and threaten global barley production. The Fusarium pathogen complex comprises several species, which are together the causal agent for Fusarium Head Blight (FHB) in cereal crops, provoking high yield and product quality losses. Fusarium spp. grain infections possess harmful mycotoxin contaminations of animal feed and human food. Zearalenone (ZEA) or trichothecens with its prominent representative deoxynivalenol (DON) are contaminants in cereal grains, among several others and their derivates [9,10]

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