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Selection of powdery mildew resistant and susceptible grapevine genotypes with molecular markers
100-104Views:108Incorporation of competitive quality and resistance against the most important fungal diseases (powdery and downy mildew) in a cultivar is one of the most important aims of grapevine breeding. In the 20th century, the most advanced results in grapevine resistance breeding were achieved by French researchers. They used resistant cultivars in more than 30% of their growing areas. In these varieties, North American wild Vitis
species were the resistance gene sources. The discovery of immunity-like resistance of Muscadinia rotundifolia opened new perspectives in resistance breeding. M. rotundifolia harbours a dominant powdery mildew gene, providing resistance in highquality cultivars after back-crosses with V. vinifera varieties. M. rotundifolia has been involved in the Hungarian grape breeding programs since 1996, thanks to a French-Hungarian variety exchange. In addition to traditional selection methods, application of MAS (Marker Assisted Selection) based on various types of
molecular markers, can provide additional tools for these efforts. Run1 locus, responsible for powdery mildew resistance, was identified in Muscadinia rotundifolia. Molecular markers closely linked to this locus are very significant in screening progenies deriving from M. rotundifolia and V. vinifera crosses, making possible the discrimination between resistant and susceptible genotypes at DNA level. In our analyses BC5 progeny of {(M. rotundifola×V. vinifera) BC4}×Cardinal (V. vinifera) tested for powdery symptoms were analysed with PCR-RFLP (GLP1- 12P1P3) and microsatellite markers (VMC4f3.1, VMC8g9). Our results proved the applicability of the linked markers and reliability of marker assisted selection. -
Use of molecular marker methods in the classification of bamboo taxa: A review
51-59Views:153Bamboo plants are currently attractive to researchers because of their versatile uses. Understanding the bamboos’ genetic level is needed to develop new varieties. Taxonomic identification is the basis for plant development. Bamboos were identified as their taxonomical morphological characters which are dependent on environmental factors. Molecular Marker techniques can be used to perform accurate genotype identification, which can be used for genetic diversity analyses. The RFLP, RAPD, AFLP, SSR, ISSR, iPBS, SCARS, SCoT, SRAP marker systems have been shown to be able to efficiently determine the genetic diversity of bamboo species based on genotyping. This paper summarizes research that aims to analyze the genetic diversity of bamboo species on a molecular basis.
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Genetic diversity of the Hungarian draft horse assessed by mitochondrial DNA
29-32Views:201Hungarian draft is a horse breed with a recent mixed ancestry. It was developed in the 1920s by crossing local mares with draught horses imported from France and Belgium. To genetically characterize the breed and to set up the basis for a conservation programme, we have employed a molecular marker: a 256-bp D-loop mitochondrial DNA fragment. We analyzed 124 horses representing Hungarian draft horses to assess the maternal phylogeography of the breed. Sequence analysis of a 256-bp segment revealed a total of 34 haplotypes with thirty-four polymorphic sites. High haplotype and nucleotide diversity values (Hd=0.953±0.001; π=0.024±0.001) were detected. The average number of pairwise differences were k=5.998. This breed counts 800 mares today, and only survive due to breeding programmes, this way each haplotype frequency depends on the extent to which mares are involved into the breeding. The reduced number of surviving maternal lineages emphasizes the importance of establishing a conservation plan for this endangered breed. Due to the revealed 34 polymorphic sites we could presuppose twelve maternal linages, which could be a first step for making a breeding programme.
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Phylogenetic analysis of Phoma species
100-107Views:92The cosmopolitan Phoma genus contains mainly phytopathogenic, opportunistic parasites, and saprophyte fungal species. Up to now, the characterization of Phoma species and other taxa of Phoma has been determined on the basis of morphology on standardized media, and gene sequence analysis was only used as a confirmative or distinctive complement.
In this study, we tried to find molecular markers which can be used as phylogenetics markers in the molecular based classification in the Phoma genus.
We employed a part of the translation elongation factor 1 subunit alpha (EF-1α=tef1) containing both introns and exons and ITS region containing the internal transcribed spacer regions 1 and 2 and the 5.8S rDNA, as potential genetic markers to infer phylogenetic relationships among different Phoma taxa. Twelve different Phoma species sequences were analysed together with the closely related Ascochyta ones. The constructed phylogenetic trees, based on tef1 and ITS sequences, do not support the traditional Phoma sections based on morphological characterization. However, we managed to distinguish between the Phoma strains and Ascochyta species by comparing their tef1 sequences through parsimony analysis. We proved that a tef1 can be a useful phylogenetic marker to resolve phylogenetic relationships at species level in Phoma genus.
Both parsimony sequence analyses confirmed that the Phyllosticta sojicola species is identical to the Phoma exigua var. exigua species as Kövics et al. (1999) claimed. However, the evolutionary distance by ITS sequences within Phoma species is too small to get well based consequences for the phylogenetic relationships of Phoma genus.
Further investigations would be necessary to clarify whether the tef1 and ITS sequences as phylogenetic molecular markers are well suited for the classification of Phoma species. -
Study of alternative oxidase as possible molecular marker for phylogenetic analysis of the Botrytis cinerea
127-132Views:114Botrytis cinerea (teleomorph Botryotinia fuckeliana (de Bary) Whetzel) is able to attack several economically important plants causing gray rot. Botrytis cinerea species complex includes two cryptic species (B. cinerea and B. pseudocinerea) that tolerate fungicides differently. On the basis of classical taxonomic markers, the two related species are very difficult to be distinguished; therefore, their separation is usually performed using molecular methods based on the time-consuming molecular analysis of several markers. Our goal was to find markers, which are suitable for the differentiation. Testing the nucleotide sequences of the alternative oxidase encoding gene, B. cinerea and B. pseudocinerea strains were clearly differentiated. Moreover, the analysis of the protein sequences of the enzyme with the maximum likelihood method reflected well the taxonomic relationships of the different fungi.