Ergot Alkaloid Contents in Hybrid Rye are Reduced by Breeding

Thomas Miedaner,Anna Kodisch,Armin Raditschnig,Jakob Eifler

doi:10.3390/agriculture11060526

Thomas Miedaner, Anna Kodisch + Show 2 more

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https://doi.org/10.3390/agriculture11060526

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Abstract

Contamination by ergot caused by the phytopathogenic fungus Claviceps purpurea is a constant threat to the whole rye value chain. Ergot alkaloids (EA) produced within the fungal sclerotia are toxic for humans and animals and are subjected to strict regulations in human food. Our main objective was to analyze whether less susceptible rye cultivars with a lower content of sclerotia also contain fewer ergot alkaloids (EA). We analyzed 15 factorial single crosses in multi-environmental trials with artificial inoculation for their ergot severity, the content of twelve EAs by HPLC, and the total ergot content by ELISA. The genotypes displayed a wide range of pollen shedding from fully sterile to fully fertile, of ergot severity expressed as percentage of sclerotia relative to the harvest (0.22–11.47%), and of EA contents when analyzed by HPLC (0.57–45.27 mg/kg. Entry-mean heritabilities were high throughout (0.87–0.98). The factorial analysis yielded a preponderance of male general combining ability (GCA) variances, the estimates for the females were smaller, although significant. EA contents measured by ELISA were, on average, seven times larger. The correlation between ergot severity and EA contents determined by HPLC was r = 0.98 (p ≤ 0.01) and only somewhat lower when analyzed by ELISA. In conclusion, less ergot prone rye genotypes also support lower EA contents.

Highlights

Ergot is a century-old problem in rye (Secale cereale L.) cultivation and the diseasecausing pathogen Claviceps purpurea (Fr.) Tul. has as generalist a wide host range with over 400 different grass species [1]
Cultivation of hybrid varieties based on cytoplasmic-male sterility (CMS) has resulted in increased ergot incidence since the mid-1980s because the required restorer-to-fertility (Rf ) genes provided only 30–50% pollen shedding at that time [7,8]
Fifteen single crosses consisting of four female and four male lines were tested for anther score, ergot severity, and ergot alkaloids (EAs) contents determined by High Performance Liquid Chromatography (HPLC) and Enzyme-Linked Immunosorbent Assay (ELISA) (Table 1)

Summary

Introduction

Ergot is a century-old problem in rye (Secale cereale L.) cultivation and the diseasecausing pathogen Claviceps purpurea (Fr.) Tul. has as generalist a wide host range with over 400 different grass species [1]. The fungus colonizes the unfertilized ovaries during flowering [2] and causes the plant to form large overwintering organs, the purple-black sclerotia [3]. They contain over 80 ergot alkaloids (EAs; [4]) that are dangerous to humans and animals [5]. Because the fungus competes with pollen for the stigma, any conditions where even only little pollen is available are conducive for infection This includes cool, damp weather at flowering that further promotes fungal infection [6].

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