1,721,020 research outputs found
Water deficit enhances anthocyanin accumulation in berry skin through up-regulation of genes of the biosynthetic pathway
No full textThe genetic background modulates the intensity of Rpv3-dependent downy mildew resistance in grapevine
No full textGrape varieties with resistance to downy mildew (DM) carry alien chromosome segments in Vitis vinifera backgrounds. We previously showed that the largest descent group shares a non-vinifera haplotype at the locus Rpv3. Here, we performed a common garden experiment with 76 varieties to evaluate the level of field resistance across four years. All varieties exhibited effector-triggered immunity (ETI)-associated necrosis. On a scale of 1–9, the median OIV452 value for foliar resistance was 7.1 in the resistant lineage vs. 3.2 in vinifera controls. Genotype, year and their interaction significantly affected the level of resistance. Some resistant genotypes showed high mean values of OIV452 and low variance among years. Other resistant genotypes showed lower mean OIV452 and higher variance. They were capable of activating ETI, but the intensity was inadequate to restrict pathogen growth under highly conducive conditions. Rpv3-dependent responses were stronger in highly native genetic backgrounds and tended to attenuate in late backcross generations. Genetic backgrounds donated by European winegrapes of the convarietas occidentalis provided on average higher levels of Rpv3 resistance than backgrounds of orientalis table grapes
Transgene-free CRISPR-Cas and cisgenesis approaches for resistance to powdery and downy mildew in grapevine
Full text linkThe development of disease-resistant tree crops is essential to sustainable agriculture, particularly under increasing biotic stresses driven by climate change. This project explores a dual strategy to confer resistance to powdery mildew (PM) and downy mildew (DM) in grapevine employing (i) a transgene-free CRISPR-Cas genome editing platform based on ribonucleoprotein (RNP) delivery, and (ii) a cisgenic transformation approach utilizing native resistance (R) genes. Both approaches rely on efficient production of embryogernic callus and regeneration of modified grapevine plants. Our CRISPR-Cas RNP system enables precise, transient gene editing without the integration of foreign DNA, targeting key susceptibility (S) genes known to be involved in PM and DM pathogenesis–specifically, MLO and DMR6 genes, respectively. In parallel, we are implementing a cisgenic strategy to introduce naturally occurring R genes from sexually compatible and disease-resistant donor genotypes. This strategy uses a binary vector system carrying a heat-inducible recombination cassette. Following selection, regenerated plants containing the cisgenic construct and the desired R gene are subjected to controlled heat shocks to activate the recombinase, leading to the excision of unwanted transgenic sequences. The resulting plants retain only the native R gene sequence. We present initial results demonstrating successful simultaneous editing of one MLO and two DMR6 genes. In cisgenic lines, we report stable expression of the Resistance to Plasmopara viticola1 (RPV1) gene. Both approaches are designed to align with emerging regulatory frameworks and enable the preservation of the genetic backrounds of elite grapevine cultivars such as Chardonnay and Merlot, which are disrupted through conventional breeding. All resulting lines from both cisgenic and gene editing strategies will undergo sequencing to assess and ensure the absence of unwanted genomic modifications
InDel markers for monitoring the introgression of downy mildew resistance from wild relatives into grape varieties
No full textWe identified haplotype-tagging insertion/deletions (InDels) for downy mildew resistance (Rpv3-1) in grapevine and converted them into InDel markers. InDel-25,941 and InDel-26,032 were validated by fragment analysis via capillary electrophoresis in 174 varieties of Vitis vinifera, 50 resistant varieties of the ‘Seibel 4614’ lineage that share Rpv3-1 by descent, and in 83 Vitis accessions. Amplicon sequencing of ancestral and derived alleles revealed that both mutations were caused by deletions. The 25,941-deletion is most likely recent. The derived allele is present only in resistant varieties obtained from ‘Seibel 4614’ and has originated in North American populations through two successive deletions within a predicted multiple stem-loop ssDNA structure, consisting of three nearby short inverted repeats, which shortened the ancestral DNA stepwise. The 26,032-deletion is more ancient. The derived allele is always present in resistant varieties of the ‘Seibel 4614’ lineage, completely absent from V. vinifera, not found in other North American accessions, and rarely present in Asian species. It may have originated in a common ancestral population before the continental disjunction, followed by incomplete lineage sorting, or in either lineage followed by introgression via secondary contacts. Genotyping with these markers does not require special instruments or chemistry for routine screening in breeding practice. Differences in amplicon size between grapes that carry or do not carry Rpv3-1 are detectable via standard agarose gel electrophoresis, or classical melting curve analysis using nonsaturating fluorescent dyes. The recombination rate between each marker and the trait locus is 0.118% for InDel-25,941 and 0.071% for InDel-26,032
DNA microsatellite in fruit crops: isolation, length polymorphism, inheritance, somatic stability, and cross-species conservation
No full textApplying a defined set of molecular markers to improve selection of resistant grapevine accessions
No full textSmart breeding programs aiming at the improvement of resistance to the
main grapevine diseases are based on the application of molecular markers related
to resistance genes. Although many markers are available in literature, a general
overview of markers associated with disease resistances and suitable for marker
assisted selection (MAS) is lacking. Hence, we propose a set of highly valuable
markers for MAS, creating a homogeneous way for the grapevine community to
proceed in smart breeding. This set is used in the project ‘RebSelect’ at Laimburg
Research Centre where a disease resistant collection is being created in collaboration
with private farmers and platforms. The collection consists of interesting hybrids
released by breeding programs around the world, containing resistances to the
principal diseases including downy and powdery mildew but also to other less
prevalent pathogens. In order to select parents with multiple resistance genes that
could be used for new crosses, the collection will be screened. Here we present
preliminary results of the application of a marker set related to resistances in the
different accessions of the collectio
Pre-symptomatic detection of Plasmopara viticola infection in grapevine leaves using chlorophyll fluorescence imaging
No full textPlasmopara viticola is an economically
important pathogen of grapevine. Early detection of
P. viticola infection can lead to improved fungicide
treatment. Our study aimed to determine whether
chlorophyll fluorescence (Chl-F) imaging can be used
to reveal early stages of P. viticola infection under
conditions similar to those occurring in commercial
vineyards. Maximum (FV/FM) and effective quantum
yield of photosystem II (ΦPSII) were identified as the
most sensitive reporters of the infection. Heterogeneous
distribution of FV/FM and ΦPSII in artificially
inoculated leaves was associated with the presence of
the developing mycelium 3 days before the occurrence
of visible symptoms and 5 days before the
release of spores. Significant changes of FV/FM and
ΦPSII were spatially coincident with localised spots of
inoculation across the leaf lamina. Reduction of FV/
FM was restricted to the leaf area that later yielded
sporulation, while the area with significantly lower
ΦPSII was larger and probably reflected the leaf parts
in which photosynthesis was impaired. Our results
indicate that Chl-F can be used for the early detection
of P. viticola infection. Because P. viticola does not
expand systemically in the host tissues and the effects
of infection are localised, Chl-F imaging at high
resolution is necessary to reveal the disease in the
field
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