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Agnese Kokina and Nils Rostoks

Genome-Wide and Mla Locus-Specific Characterisation of Latvian Barley Varieties

Genetic diversity in locally adapted germplasm forms the basis for crop improvement through breeding. While single loci have been routinely used for studies of genetic diversity, the highthroughput genotyping platforms that have recently become available for large genome crop plants offer an unbiased view on genetic diversity on a genome-wide scale. We assessed genetic diversity in Latvian barley varieties and some progenitors using DArT markers and studied the extent of linkage disequilibrium in Latvian germplasm. Further, genetic diversity at three loci flanking the barley powdery mildew Mla locus conferring race-specific resistance was studied in Latvian barley germplasm. The Mla locus encompasses several closely related resistance gene homologues with a complex evolutionary history, which complicates the design of molecular markers for different Mla genes. We observed significant linkage disequilibrium between the single nucleotide polymorphisms (SNPs) at the three loci, 206i20_T7, ABC15612, and 538P8, flanking the Mla locus. SNP haplotypes were largely in agreement with known phenotypic data and, thus, may be potentially diagnostic for Mla resistance genes in hybrids.

Open access

Anta Sparinska and Nils Rostoks

Abstract

Hybrid Rugosa is the most winter hardy group of roses in the climatic conditions of the Baltic Sea region. This study aimed at identifying new qualities of Hybrid Rugosa by focusing on determination of content of volatile organic compounds of flower petals and in hydrosols produced from these. Volatiles of seven cultivars were extracted using solid phase microextraction (SPME) with subsequent separation by gas chromatography. Identification was made by comparison with mass spectral libraries and by calculating linear retention indexes and comparing them with literature data. Twenty-five volatile aroma compounds were identified in the petals and hydrosols of six Hybrid Rugosa and species. Among those, phenylethylalcohol, ß-citronellol, geraniol and nerol were predominant. Species Rosa rugosa and variety ‘Plena’ showed the highest total level of volatiles and contained 26% and 31% ß-citronellol, respectively. Varieties ‘Raita’ and ‘Sniedze’ contained up to 57% citronellol. The main volatile compounds were detected in hydrosols in the same proportions, but their concentration was higher than in petals. The varieties ‘Raita’ and ‘Violeta’, bred in Latvia, are recommendable for use as a source of hydrosol.

Open access

Māra Bleidere, Ieva Mežaka, Linda Legzdiņa, Ilze Grunte, Indra Beinaroviča and Nils Rostoks

Variation of spring barley agronomic traits significant for adaption to climate change in latvian breeding programmes

Breeding programmes have been recently challenged by climate change. Spring barley (Hordeum vulgare L.) yield, phenological traits (days to heading, length of filling period and days to maturity) and resistance to powdery mildew and net blotch, which are influenced by the rising temperature and precipitation, along with threshability in hulless, were evaluated and their genetic and environmental variability were determined. One hundred and ninety spring barley genotypes were studied, including 129 hulless genotypes and 61 hulled genotypes. The genotypes were grown in the State Stende Cereal Breeding Institute and State Priekuļi Plant Breeding Institute for three seasons during 2007-2009. Broad-sense heritability estimated on the basis of genotypical and phenotypical variances for all traits of hulled barley varied from 31 to 98, and 42 to 98% for hulless barley. For both types of barley the highest heritability was observed for days to heading, filling period and days to maturity. Despite the relatively high estimated heritability for all traits, nevertheless, location, year and interaction of genotype and environment were also been significant for all traits.

Open access

Nadezhda Zoteyeva, Ilze Skrabule, Ieva Mežaka, Daiga Vilcāne, Guna Usele and Nils Rostoks

Abstract

Potato breeding clones were evaluated for resistance to late blight (agent Phytophthora infestans) using tuber inoculation tests and for presence of the resistance alleles of R1 and R3a genes in polymerase chain reaction tests. Among clones tested those expressing high, moderate and low resistance were identified. The data were analysed for the impact of R1 and R3a genes on tuber resistance to late blight in tested plant material. In previous evaluations performed on smaller amount of clones the tuber resistance levels significantly depended on presence/absence of the resistance allele of R3a gene and did not depend on presence of R1 gene allele. In the current study the statistical analyses did not prove the significant difference in resistance levels depending on presence of the resistance alleles, neither of R1 gene, nor of R3a gene. Tuber resistant clones bearing R3a gene resistance alleles still noticeably prevailed over the clones bearing the alleles of R1 gene as well as over the clones bearing the no resistance alleles of both genes. In several cases the resistance of clones with detected resistance allele of R1 gene was higher compared to those derived from the same crosses and showing amplification of the allele of R3a gene or those with no resistance alleles. Clones accumulating the resistance alleles of both (R1 and R3a) genes expressed high tuber resistance accompanied by necrotic reaction.

Open access

Nadezhda Zoteyeva, Ieva Meþaka, Daiga Vilcâne, Ulrika Carlson-Nilsson, Ilze Skrabule and Nils Rostoks

Abstract

The oomycete Phytophthora infestans Mont. (de Bary), which causes potato late blight, and Potato Virus Y (PVY) are economically important potato pathogens. More virulent P. infestans strains have evolved and are able to overcome resistance genes introgressed earlier to cultivated potato from wild Solanum species, especially from S. demissim Lindl. Potato cultivars resistant to the previously common type of PVYN may be susceptible to the more virulent isolates of PVY. In previous research, S. guerreroense Corr. (grr) and S. neoantipoviczii Buk. (nan) accessions were rated as resistant to P. infestans and to two (grr) and three (nan) strains of PVY. These parental accessions and their respective hybrid offspring were screened using polymerase chain reaction (PCR) tests to detect alleles conferring resistance to P. infestans (R1 and R3) and to PVY (Rysto). Screenings were made in detached leaflet tests (P. infestans), and with the aid of ELISA tests (PVY). The resistance of two hybrids derived from grr was rated as high, mostly due to a hypersensitivity reaction. The allele R3 was detected in only one grr plant among 20 plant populations for each grr and nan accession. R1 and R3 alleles were more frequently detected in one hybrid of grr (grr × B.d.R5.). The resistance allele Rysto was found in nan and provided host plant resistance to three strains of PVY, including PVYNTN. Hybrids derived from this accession were characterised by a high frequency of plants bearing the resistant allele Rysto. In the parental clone tbr × phu, as well as in grr and its hybrids, only the susceptible allele at Rysto locus was detected.