1,721,080 research outputs found
Landscape discontinuities influence the population structure of Acer opalus ssp. obtusatum Waldst. & Kit. ex Willdenow
No full textThe major goal of landscape genetics is to understand how landscape structure genetic variation in natural populations. We
investigated molecular diversity in Acer opalus subsp. obtusatum sampled from 95 sites using 14 nuclear microsatellite loci.
The average number of alleles per nuclear microsatellite locus differed among sampling sites; the number was high (4.9
alleles) in populations from the Basilicata and Molise regions, where heterozygosity was also high (0.679, Molise; 0.669,
Basilicata). Differentiation between sites was often low (mean FST 1⁄4 0.220), indicating few genetic differences between
most sites. There was a clear excess of homozygotes (mean Ho 1⁄4 0.450, mean He 1⁄4 0.513) and a relatively high FIS
(mean 1⁄4 0.451), suggesting a consistent level of inbreeding in many A. opalus subsp. obtusatum populations. There was a
significant pattern of isolation by distance across the study area (Mantel test; R 2 1⁄4 0.0662, P , 0.001). Two assignment
methods (Structure and Geneland) produced some similarities in their definitions of population structure, especially for
populations from the Campania and Tuscany regions. These two important genetic discontinuities were not associated with
any physical barrier
Evidence of chloroplast DNA variation in the genus Actinidia revealed by restriction analysis of PCR-amplified fragments
No full textPaternal inheritance of chloroplast DNA and maternal inheritance of mitochondrial DNA in the genus Actinidia
No full textPCR ampliÞcation of four chloroplast DNA
(cpDNA) and two mitochondrial DNA (mtDNA) regions
followed by restriction of the ampliÞed products
was used to identify restriction fragment length polymorphisms
in 21 Actinidia taxa. Subsequently, the
mode of organelle inheritance was investigated in both
interspeciÞc and intraspeciÞc controlled crosses made
between genotypes showing di¤erent cpDNA and/or
mtDNA haplotypes. Fifty-six seedlings produced from
three interspeciÞc crosses, including in one case the
pseudo reciprocal (di¤erent genotypes of the same
species used as opposite parents), were checked for
cpDNA inheritance, and 102 seedlings from the same
interspeciÞc crosses and 32 seedlings from two intraspeci
Þc crosses within the species A. deliciosa were
checked for mtDNA inheritance. In all cases, cpDNA
was inherited from the father and mtDNA was inherited
from the mother. Maternal inheritance of mtDNA
was expected, being the rule in plants, but A. deliciosa is
the Þrst genus in angiosperms for which a widespread
and strictly paternal inheritance of cpDNA has been
reported. Transmission of chloroplastic and mitochondrial
genomes through opposite parents provides an
exceptional opportunity for studying the paternal and
maternal genetic lineages of species in the genus
Actinidia
Resistence gene analogs are candidate markers for disease-resistance genes in grape (Vitis spp.)
No full textNucleotide binding site/leucine-rich repeats, Pto-like and receptor-like kinases related to disease resistance in grapevine
No full textNucleotide Binding Site/Leucine-Rich Repeat (NBS-LRR) and Serine/Threonine Kinase (STK) genes are two of the known classes of resistance (R-) genes in plants, and occur in large multigene families. Systematic identification of genes for NBS-LRRs and STKs provides a means of access to genomic regions that may be involved in disease resistance. Here we present a picture of these two families of R-gene analogs (RGAs) in grape with the aim of developing a set of resistance-related sequence-tagged-site (STS) markers. One hundred and three NBS-LRR sequences were isolated. They included members of the CC (coiled-coil) and TIR (Toll-interleukin receptor) sub-classes. A comparative analysis with other angiosperm NBSs is provided. Fifty-three genes for receptor-like kinases (RLKs) with serine/threonine specificity were identified. RLK sequences formed a putative monophyletic group within the kinase superfamily. They were similar to both cytoplasmic RLKs, such as Pto, and RLKs with LRR, S-locus, lectin-like and thaumatin-like extracellular binding-domains. The latter resembled the products of the R-related genes Xa21, FLS2, Rlk10, SFR2, and PRSK. Forty-five reference RGAs were converted into STSs by using appropriately designed specific primers. RGA-STSs were present in diverse grape genotypes, and > 85% of the primers were capable of amplifying the STSs across the taxa Vitis and Muscadinia. DNA sequence polymorphism among these RGAs was assessed by SSCP (single-strand conformation polymorphism) analysis in over 20 Vitis spp. Finally, 45 universal primers for grape RGAs are proposed that should permit tagging of R-related regions in any grape genome
Molecular characterization of the autochthonous grape cultivars of the region Friuli Venezia Giulia - North-Eastern Italy
No full textEffects of fragmentation phenomena on the genetic structure and gene flow in Centaurea cineraria group (Asteraceae) in the Mediterranean Basin
No full textThe complex history of the Mediterranean region illustrates how ancient and recent phenomena are closely associated with
species distribution and the creation of phylogeographic divisions within Mediterranean flora. A good model to explore the
genetic consequences of fragmentation can be found in Centaurea cineraria and its close relatives.We applied simple sequence
repeat molecular markers to a dense population sampling throughout the distribution area of all C. cineraria taxa to study how
fragmentation has altered the genetic structure and distribution of C. cineraria. The average gene diversity (He) was 0.286,
and the average allelic richness (Ar) was 3.65 and ranged from 2.15 (C. gymnocarpa) to 5.25 (C. busambarensis). The FIS
averaged a relatively high 0.223, ranging from 20.724 in C. aeolica subsp. aeolica to 0.589 in C. leucadea. Our results indicate
that habitat fragmentation over several generations reduced heterozygosity due to random genetic drift in populations of C.
cineraria. This heterozygosity erosion becomes more severe when the inbreeding coefficient is positive and the outcrossing
rates show a significant increase. The results observed for outcrossing rates and inbreeding coefficient could also indirectly
support the possibility of disrupted gene flow or mating pattern changes in fragmented C. cineraria population
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