Maternal differences for the reaction to ergot in unfertilized hybrid rye (Secale cereale)

Abstract

Claviceps purpurea causing ergot maintains to be a problem in commercial cytoplasmic male sterile (CMS)-based hybrid rye growing. The fungal spores compete with pollen during flowering and ergot incidence is reduced in highly pollen-shedding stands. This study was carried out to identify maternal differences in ergot infection in the absence of pollen. Ten male-sterile single crosses were tested by needle and spray inoculation and kept unfertilized in up to four field sites (Germany, Austria) and three greenhouse experiments, respectively, in two years. A medium to high correlation was observed between field (needle inoculation) and greenhouse (spray inoculation) experiments. The environments (=location × year combinations) differed in their ergot severity and ergot incidence. Significant (P ≤ 0.05) genotypic and genotype × environment interaction variances were detected for the unfertilized male-sterile single crosses in both test systems for both traits. The single cross K_4 showed a significantly lower ergot severity averaged across all environments, thus being more resilient to ergot than the other genotypes. In conclusion, spray and needle inoculation are suitable for testing unfertilized male-sterile rye materials, testing across several environments (locations, years) is definitely necessary. Selection of specific females might give the potential for further reducing ergot contamination in hybrid rye in future. The frequency of such genotypes within larger breeding populations needs to be analyzed.

Effective Pollen-Fertility Restoration Is the Basis of Hybrid Rye Production and Ergot Mitigation

“…Thus, the host obviously recognizes the Claviceps infection. Indeed, it has been shown several times that diverse sets of both fully pollen-fertile rye and fully malesterile rye, when grown under pollen-isolated conditions, showed small but significant differences in their ergot reaction [75][76][77]. These quantitative maternal differences could be exploited by targeted selection, as shown by some commercial hybrids without Rfp1 genes and with a low restorer index, as well as lower ergot severity even after artificial infection (Figure 8).…”

ERGOT Claviceps purpurea (Fries) Tulasne ALKALOID DIVERSITY AND VIRULENCE: EVOLUTION, GENETIC DIVERSIFICATION, AND METABOLIC ENGINEERING (review)

“…Гибридная селекция ржи позволяет увеличить урожайность зерна, одновременно усиливая чувствительность к спорынье, связанную с цитоплазматической мужской стерильностью (CMS), которая наследуется по материнской линии (215,216). Тесная связь между наличием фертильной пыльцы и чувствительностью к спорынье создает проблему для селекции (213,215,217).…”