Home About us Contact
|
Home About us Contact | ||
|
|
||
Thaliana Accessions (thaliana + accession)
Kinds of Thaliana Accessions Selected AbstractsLight and Electron Microscopy of the Compatible Interaction Between Arabidopsis and the Downy Mildew Pathogen Peronospora parasiticaJOURNAL OF PHYTOPATHOLOGY, Issue 6 2003E. M. Soylu Abstract In this study, we focused on compatible interactions between Peronospora parasitica isolate Emoy-2 and wild-type (Oy-0) and mutant (Ws- eds1) Arabidopsis thaliana accessions by using light and transmission electron microscopy (TEM). Light microscopy of compatible interactions revealed that conidia germinated and penetrated through the anticlinal cell walls of two epidermal cells. Rapid spreading of the hyphal growth with formation of numerous haustoria within the mesophyll cells was subsequently followed by profuse sporulation in the absence of host cell necrosis on both wild-type and mutant accessions. TEM observations revealed that coenocytic intercellular hyphae ramified and spread intercellularly throughout the host tissue forming several haustoria in host mesophyll cells. Intracellular haustoria were lobed with the diameter of 6,7 ,m. Each haustorium was connected to intercellular hyphae in the absence of apparent haustorial neck. The cytoplasm of the haustorium included the organelles characteristic of the pathogen. Callose-like deposits were frequently observed at sites of penetration around the proximal region of the haustorial neck. Apart from a few callose ensheatments, no obvious response was observed in host cells following formation of haustoria. Most of mesophyll cells contained normal haustoria and the host cytoplasm displayed a high degree of structural integrity. Absence of host cell wall alteration and cell death in penetrated host cell of both accessions suggest that the pathogen exerts considerable control over basic cellular processes and in this respect, response to this biotroph oomycete differs considerably from responses to other pathogens such as necrotrophs. [source] Sequence diversity and haplotype associations with phenotypic responses to crowding: GIGANTEA affects fruit set in Arabidopsis thalianaMOLECULAR ECOLOGY, Issue 14 2007MARCUS T. BROCK Abstract Identifying the molecular genetic basis of intraspecific variation in quantitative traits promises to provide novel insight into their evolutionary history as well as genetic mechanisms of adaptation. In an attempt to identify genes responsible for natural variation in competitive responses in Arabidopsis thaliana, we examined DNA sequence diversity at seven loci previously identified as members of the phytochrome B signalling network. For one gene, GIGANTEA (GI), we detected significant haplotype structure. To test for GI haplogroup,phenotype associations, we genotyped 161 A. thaliana accessions at GI and censused the same accessions for total fruit set and the expression of three phenotypic traits (days to flowering, petiole length, and inflorescence height) in a greenhouse experiment where plants were grown in crowded and uncrowded environments. We detected a significant association between GI and total fruit set that resulted in a 14% difference in average fruit set among GI haplogroups. Given that fruit set is an important component of fitness in this species and given the magnitude of the effect, the question arises as to how variation at this locus is maintained. Our observation of frequent and significant epistasis between GI and background single nucleotide polymorphisms (SNP), where the fitness ranking of the GI allele either reverses or does not differ depending on the allele at the interacting SNP, suggests that epistatic selection may actively maintain or at least slow the loss of variation at GI. This result is particularly noteworthy in the light of the ongoing debate regarding the genetic underpinnings of phenotypic evolution and recent observations that epistasis for phenotypic traits and components of fitness is common in A. thaliana. [source] Maintenance of genetic variation in plants and pathogens involves complex networks of gene-for-gene interactionsMOLECULAR PLANT PATHOLOGY, Issue 4 2009SHARON A. HALL SUMMARY The RPP13 [recognition of Hyaloperonospora arabidopsidis (previously known as Peronospora parasitica)] resistance (R) gene in Arabidopsis thaliana exhibits the highest reported level of sequence diversity among known R genes. Consistent with a co-evolutionary model, the matching effector protein ATR13 (A. thaliana -recognized) from H. arabidopsidis reveals extreme levels of allelic diversity. We isolated 23 new RPP13 sequences from a UK metapopulation, giving a total of 47 when combined with previous studies. We used these in functional studies of the A. thaliana accessions for their resistance response to 16 isolates of H. arabidopsidis. We characterized the molecular basis of recognition by the expression of the corresponding ATR13 genes from these 16 isolates in these host accessions. This allowed the determination of which alleles of RPP13 were responsible for pathogen recognition and whether recognition was dependent on the RPP13/ATR13 combination. Linking our functional studies with phylogenetic analysis, we determined that: (i) the recognition of ATR13 is mediated by alleles in just a single RPP13 clade; (ii) RPP13 alleles in other clades have evolved the ability to detect other pathogen ATR protein(s); and (iii) at least one gene, unlinked to RPP13 in A. thaliana, detects a different subgroup of ATR13 alleles. [source] Competitive ability not kinship affects growth of Arabidopsis thaliana accessionsNEW PHYTOLOGIST, Issue 1 2010Frédéric Masclaux Summary ,In many organisms, individuals behave more altruistically towards relatives than towards unrelated individuals. Here, we conducted a study to determine if the performance of Arabidopsis thaliana is influenced by whether individuals are in competition with kin or non-kin. ,We selected seven pairs of genetically distinct accessions that originated from local populations throughout Europe. We measured the biomass of one focal plant surrounded by six kin or non-kin neighbours in in vitro growth experiments and counted the number of siliques produced per pot by one focal plant surrounded by four kin or non-kin neighbours. ,The biomass and number of siliques of a focal plant were not affected by the relatedness of the neighbour. Depending on the accession, a plant performed better or worse in a pure stand than when surrounded by non-kin plants. In addition, whole-genome microarray analyses revealed that there were no genes differentially expressed between kin and non-kin conditions. ,In conclusion, our study does not provide any evidence for a differential response to kin vs non-kin in A. thaliana. Rather, the outcome of the interaction between kin and non-kin seems to depend on the strength of the competitive abilities of the accessions. [source] Genetic analysis identifies quantitative trait loci controlling rosette mineral concentrations in Arabidopsis thaliana under droughtNEW PHYTOLOGIST, Issue 1 2009Artak Ghandilyan Summary ,,Rosettes of 25 Arabidopsis thaliana accessions and an Antwerp-1 (An-1) × Landsberg erecta (Ler) population of recombinant inbred lines (RILs) grown in optimal watering conditions (OWC) and water deficit conditions (WDC) were analysed for mineral concentrations to identify genetic loci involved in adaptation of mineral homeostasis to drought stress. ,,Correlations between mineral concentrations were determined for accessions and a quantitative trait locus (QTL) analysis was performed for the RIL population. ,,Plant growth and rosette mineral contents strongly decreased in WDC compared with OWC. Mineral concentrations also generally decreased, except for phosphorus (P), which remained constant, and potassium (K), which increased. Large variations in mineral concentrations were observed among accessions, mostly correlated with total rosette leaf area. Mineral concentration QTLs were identified in the RIL population, but only a few were common for both conditions. Clusters of mineral concentration QTLs often cosegregated with dry weight QTLs. ,,Water deficit has a strong effect on rosette mineral status. This is genetically determined and seems largely a pleiotropic effect of the reduction in growth. The low number of common mineral concentration QTLs, shared among different RIL populations, tissues and conditions in Arabidopsis, suggests that breeding for robust, mineral biofortified crops will be complex. [source] Arabidopsis proteins important for modulating defense responses to Pseudomonas syringae that secrete HopW1-1THE PLANT JOURNAL, Issue 3 2008Min Woo Lee Summary Plant infection responses result from the interaction of pathogen-derived molecules with host components. For the bacterial pathogen Pseudomonas syringae, these molecules are often effector proteins (Hops) that are injected into plant cells. P. syringae carrying hopW1-1 have restricted host range on some Arabidopsis thaliana accessions. At least two Arabidopsis genomic regions are important for the natural variation that conditions resistance to P. syringae/hopW1-1. HopW1-1 elicits a resistance response, and consequently the accumulation of the signal molecule salicylic acid (SA) and transcripts of HWI1 (HopW1-1-Induced Gene1). This work identified three HopW1-1-interacting (WIN) plant proteins: a putative acetylornithine transaminase (WIN1), a protein phosphatase (WIN2) and a firefly luciferase superfamily protein (WIN3). Importantly, WIN2 and WIN3 are partially required for HopW1-1-induced disease resistance, SA production and HWI1 expression. The requirement for WIN2 is specific for HopW1-1-induced resistance, whereas WIN3 is important for responses to several effectors. Overexpression of WIN2 or WIN3 confers resistance to virulent P. syringae, which is consistent with these proteins being defense components. Several known genes important for SA production or signaling are also partially (EDS1, NIM1/NPR1, ACD6 and ALD1) or strongly (PAD4) required for the robust resistance induced by HopW1-1, suggesting a key role for SA in the HopW1-1-induced resistance response. Finally, WIN1 is an essential protein, the overexpression of which over-rides the resistance response to HopW1-1 (and several other defense-inducing effectors), and delays SA and HWI1 induction. Thus, the WIN proteins have different roles in modulating plant defense. [source] | ||||||||||