1,721,146 research outputs found
Plant regeneration and transformation in the Rosaceae
Full text linkThe plant family Rosaceae consists of over 100 genera and 3,000 species that include many important fruit, nut, ornamental, and lumber crops. Members of this family provide high-value nutritional foods and contribute desirable aesthetic and industrial products. A complete annotated genome sequence is expected momentarily for apple, and in the near future for peach and strawberry. These sequences will accelerate the next wave of research exploring and comparing the form and function of the many genomes that define the striking differences in morphology and physiology among the Rosaceae, e.g., a herbaceous plant vs. a tree, or a fleshy rather than a dehiscent fruit. Among the many dividends of this research will be the development of superior products for consumers, a better understanding of the genetic elements that contribute to horticultural traits of interest, and an enhanced vision of Rosaceae evolution. It will also answer some of the fundamental questions of plant biology, particularly around the regulation of plant architecture, which may be best answered by species within this family. This review serves as a synopsis of the genetic engineering resources available to study the function and production of new Rosaceae varieties of benefit to the consumer
Overexpressing a molecular target of SAP11CaPM in apple
Full text linkThe bacterial effector SAP11CaPM can bind several members of the TCP transcription factor gene family. To investigate the role of the interaction in the infection process, apple plants stably overexpressing the MdTCP4a gene were generated and infected with a ‘Candidatus Phytoplasma mali’ strain. Preliminary results show a statistically significant lower concentration of the phytoplasma in the aerial parts of the in vitro transgenic lines than in the non-transformed “Gala” plants, suggesting that the overexpression of MdTCP4a gene could limit phytoplasma multiplication. Interestingly, soil-acclimatized transgenic plants displayed phenotypic characteristics similar to the symptoms of apple proliferatio
Malus genome editing via CRISPR/CAS9 to develop sustainable and pest free apples
No full textMost commercial apples are sensitive to pathogens causing re blight (Erwinia amylovora) and powdery mildew (Podosphaera leucotricha). The control
of these pathogens requires pesticides and eradication with a negative impact on the environment and huge economic losses. Resistant varieties were
obtained by classical breeding via the transfer of resistance genes (R-genes) from wild apples, but this approach is time-consuming, leads to low-quality
plants, and the adjunct resistance is not durable. The suppression of susceptibility genes (S-genes) could be used to confer durable resistance to apples
but past attempts to knock-down S-genes were mostly transgenic-based thus limiting the use of resulting plants. The aim of this project is to use
CRISPR/Cas9 to develop pest-free apples by simultaneously mutating S-genes responsible for the susceptibility to E. amylovora and P. leucotricha.
Gene mutation is obtained through the delivery of a vector containing the editing machinery combined with a heat-inducible recombination system to
permit the elimination of vector DNA from the genome of plants after editing. Here we present the results obtained from the Agrobacterium-mediated
delivery of this heat-excisable editing system. More than 50 Gala and Golden Delicious lines with no evident growth deciencies were regenerated and
conrmed for T-DNA integration by PCR. Single-pass sequencing indicated that about 80 % of such lines were edited in at least one of the four target
genes and 30 % had all the four genes edited. Preliminary Illumina sequencing data (19 lines) revealed that editing events were mostly constituted by
small deletions (<6 bp). Plants edited for single and multiple genes are planned to be scored for re blight and powdery mildew resistance and then to
be submitted to heat-treatments for the excision of the editing cassette. A protoplast-to-plant regeneration procedure will also be developed during
the project to allow DNA-free genome editing
Attesa una decisione della Commissione europea sui prodotti delle nuove tecniche di miglioramento genetico
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Malus fusca fire blight resistance: identification of a candidate gene on chromosome 10 and a novel minor locus on chromosome 16
No full textFire blight resistance of the wild apple species Malus fusca (accession MAL0045) has been previously reported.
This accession, crossed with the domesticated apple cultivar ‘Idared’, allowed for studies on the genetics of
the resistance of this crabapple with the resultant F1 population. A major fire blight locus (Mfu10), found on
chromosome 10, explained up to 66% of the phenotypic variance amongst the M. fusca × ‘Idared’ progenies.
Although fire blight resistance is strain specific for some Malus accessions, leading to the breakdown of resistance
in few resistance donors by highly aggressive strains of Erwinia amylovora; no strain able to breakdown the
resistance of M. fusca itself or Mfu10 has been found. This makes this wild apple an interesting model for
resistance studies with different wild-type and mutant strains of E. amylovora. A candidate gene (FB_Mfu10),
underlying the major locus, was recently proposed. FB_Mfu10 was predicted on the sequence of a bacterial
artificial chromosome (BAC) clone, spanning the fire blight locus on chromosome 10 and encodes B-lectin and
serine/threonine kinase domains. Preliminary functional analyses showed, that the open reading frame (ORF),
together with its border sequences upstream of the start codon and downstream of the stop codon (~ 6000 bp), is
present only in resistant F1 genotypes with 8bp distinguishing between susceptibility and resistance. Furthermore,
with a dense genetic map of M. fusca and studies with a mutant of an aggressive strain of E. amylovora, a minor
fire blight locus has been identifie
Status of fire blight resistance breeding in Malus
No full textMalus domestica (apple) is one of the most important fruit crops worldwide. Fire blight, caused by Erwinia amylovora, is one of the most destructive bacterial diseases that impacts apple production systems worldwide. Although it is possible to manage fire blight using antibiotics such as streptomycin, kasugamycin or oxytetracycline, the quest for sustainable and eco-friendly production makes breeding for fire blight resistance the most promising and desirable approach. Breeding for resistance is a long, resource-intensive process due to the high susceptibility of most commercial apple cultivars, and the fact that most resistance sources being characterized are from wild genetic backgrounds with unpalatable fruits, and apple’s long generation times. Nevertheless, establishment of pre-breeding materials is crucial. This review highlights the status of breeding for fire blight resistance in Malus, taking into account, 1) major and minor resistance sources and their interaction with E. amylovora, 2) progress and challenges associated with using wild species as resistance sources, 3) progress and challenges associated with using elite cultivars as resistance sources, 4) advances in biotechnology for use in enhancing the production of durable fire blight resistant cultivar
Genetic analysis and fine mapping of the fire blight resistance locus of Malus ×arnoldiana on linkage group 12 reveal first candidate genes
Full text linkMalus ×arnoldiana accession MAL0004 has been found to be resistant to moderately and highly virulent strains of the fire blight causal pathogen – the Gram-negative bacterium, Erwinia amylovora. Genetic analyses with an F1 segregating population derived from crossing the highly susceptible apple cultivar ‘Idared’ and MAL0004 led to the detection and mapping of the fire blight resistance locus of M. ×arnoldiana to linkage group (LG)12 (FB_Mar12). FB_Mar12 mapped at the distal end of LG12 below the apple SSR Hi07f01 in an interval of approximately 6 cM (Centimorgan), where both the fire blight resistance loci of M. floribunda 821 and ‘Evereste’ were located. We fine mapped the region containing FB_Mar12 using 892 progenies. Mining of the region of interest (ROI) on the ‘Golden Delicious’ doubled haploid genome (GDDH13) identified the presence of 2.3 Mb (megabases) in the homologous region. Of 40 primer pairs designed within this region, 20 were polymorphic and nine were mapped, leading to the identification of 24 significant recombinant individuals whose phenotypes were informative in determining the precise position of the locus within a 0.57 cM interval. Analyses of tightly linked marker sequences on the M. baccata draft genome revealed scaffolds of interest putatively harboring the resistance loci of M. ×arnoldiana, a hybrid between M. baccata and M. floribunda. Open reading frame (ORF) analyses led to the prediction of first fire blight resistance candidate genes with serine/threonine kinase and leucine-rich repeat domains, including homologs of previously identified ‘Evereste’ candidate genes. We discuss the implications of these results on breeding for resistance to fire blight
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