Behavior of Spanish durum wheat genotypes against Zymoseptoria tritici: resistance and susceptibility

Rafael Porras,Alejandro Pérez-De-Luque,Josefina C Sillero,Cristina Miguel-Rojas

doi:10.5424/sjar/2021193-17953

Abstract

Aim of study: Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici, is one of the most important wheat diseases worldwide, affecting both bread and durum wheat. The lack of knowledge about the interaction of durum wheat with Z. tritici, together with limited resources of resistant durum wheat material, have both led to a rising threat for durum wheat cultivation, particularly in the Mediterranean Basin. In Spain, STB has increased its incidence in the last few years, leading to higher costs of fungicide applications to control the disease. Therefore, identification of new sources of resistance through wheat breeding stands out as an efficient method of facing STB.Area of study: The experimental study was conducted in growth chambers at the IFAPA facilities in Córdoba (Spain).Material and methods: The percentage of necrotic leaf area, the disease severity, and the pycnidium development through image analysis were evaluated from 48 durum wheat Spanish accessions (breeding lines and commercial cultivars) in growth chambers against an isolate of Z. tritici from Córdoba.Main results: Two breeding lines and six commercial cultivars showed resistant responses by limiting STB development through the leaf or its reproduction ability, while the other 40 accessions presented a susceptible response.Research highlights: Provided these resources of resistance in Spanish durum wheat genotypes, future breeding programs could be developed, incorporating both agronomic traits and resistance to STB.

Highlights

Wheat is the most widespread crop, growing on about 214 million hectares globally, leading the production of cereals with 734 million tons, and providing a large proportion of human diets
The accessions expressed, on average, 62.2% necrotic leaf area (NLA), with most accessions falling in the range of 55-75%, indicating the great development capability of Z. tritici amongst them
Most of the durum wheat accessions studied presented 50% or higher mean values of NLA, which suggests an elevated development of Z. tritici in the leaf tissue amongst groups with diverse genetic origin

Summary

Introduction

Wheat is the most widespread crop, growing on about 214 million hectares globally, leading the production of cereals with 734 million tons, and providing a large proportion of human diets (http://www.fao.org/faostat/es/#home). Z. tritici can be considered as a hemibiotrophic fungus because it colonizes the intercellular space surrounding the mesophyll cells without visible symptoms, which typically occurs for 10-15 days after infection (biotrophic phase) This biotrophic phase is followed by a necrotrophic phase, in which the infection causes chlorotic lesions and later necrotic blotches on wheat, bearing fruiting bodies called pycnidia in the colonized substomatal cavities (Somai-Jemmali et al, 2017b). Distribution of Z. tritici covers temperate climates where wheat cropping plays an important role, and extends to hot dry climates such as the Mediterranean Basin, North Africa, or Iran, where durum wheat cultivation stands out because of its importance in the Mediterranean diet (Hosseinnezhad et al, 2014; Benbelkacem et al, 2016; Ünal et al, 2017; Chedli et al, 2018) This global spread of Z. tritici is due to its rapid evolution and adaptation to diverse agricultural conditions (McDonald & Mundt, 2016). This ability of adaptation implies a resistance to multiple fungicides, which causes an annual cost of ~1 billion euros (70% annual cereal fungicide usage) in the EU only, thereby representing one of the most important foliar diseases of wheat (Torriani et al, 2015)

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