Genotype Heterogeneity in Accessions of a Winter Barley Core Collection Assessed on Postulated Specific Powdery Mildew Resistance Genes

Abstract

Gene bank accessions are necessary for implementing many research and breeding projects. However, a great number of accessions are contaminated or confused. If such accessions are used, the results obtained from these projects are inaccurate and non-reproducible. There are methods that allow almost perfect genotype identification; nevertheless, they are relatively recent and results cannot be compared with the characteristics of the original accessions. Growing resistant cultivars is an environmentally safe and cheap way of disease management and knowledge of diverse resistance genes and their combinations can be used to identify varieties and verify their authenticity and homogeneity. For this purpose, all 172 accessions of the core collection (CC) of the Czech winter barley (Hordeum vulgare) gene bank, originating from 35 countries, were studied. For resistance tests, 51 reference isolates of Blumeria graminis f.sp. Hordei, collected in all nonpolar continents over a period of 63 years and representing the global virulence/avirulence diversity of the pathogen, were used. Only 25 barley accessions were homogeneous (genetically uniform), whereas 147 accessions were heterogeneous due to presence of different genotypes. In total, 17 resistance genes were found singly or in combinations; 76.3% of accessions with identified resistance genes carried alleles at the Mla locus. To purify the CC, progenies of individual plants must be multiplied and authenticity and homogeneity of the seed should be confirmed with resistance tests, and subsequently can be studied with more advanced methods.

Powdery Mildew Resistance Genes in Single-Plant Progenies Derived from Accessions of a Winter Barley Core Collection

“…This contribution describes the identification of the powdery mildew resistance genes in single-plant progenies (SPPs) of accessions of the core collection (CC) of the Czech winter barley gene bank. Results from a similar project have already been reported [ 8 ], but more than 85% of the accessions showed heterogeneity in their resistance and identification of resistances was limited. Therefore, the aims of this study were i) to grow a technically-manageable group of homogeneous samples (lines) in order to record the most frequent genotypes present in each accession; ii) to identify resistance genes in each of them, and iii) to evaluate their authenticity.…”

“…The first cultivar with a gene located at the Mla locus was Vogelsanger Gold ( Mla6 ) derived from wild barley ( Hordeum vulgare subsp. spontaneum ) and many subsequent cultivars were bred with other new resistances, mainly alleles of Mla locus [ 6 , 8 ]. Later, it was found that even European landraces carry some specific resistance genes completely ineffective in the field [ 9 ].…”

Powdery Mildew Resistance Phenotypes of Wheat Gene Bank Accessions

“…Gene bank accessions are commonly characterized by high genotypic heterogeneity [ 11 ]. Therefore, ear progenies of the tested cultivars were grown for this project.…”

“…The following methods, especially in Section 2.2 and Section 2.3 , are similar to those previously described [ 11 ].…”

RACE1, a Japanese Blumeria graminis f. sp. hordei isolate, is capable of overcoming partially mlo-mediated penetration resistance in barley in an allele-specific manner

“…In fact, Reinstädler et al [ 48 ] reported that one of eight “ mlo -11 mutant alleles” tested was not mlo -11. Recently, it was also reported that about 85% of accessions of the core collection of the Czech winter barley gene bank was heterogenous [ 49 ]. In addition, we found that the wild-type Diamant seeds were suspected to be heterogenous due to contamination with other mlo mutant alleles, and avoided using them.…”