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1.
Background and Aims
Genotype by environment (G × E) interactions are important for the long-term persistence of plant species in heterogeneous environments. It has often been suggested that disease is a key factor for the maintenance of genotypic diversity in plant populations. However, empirical evidence for this contention is scarce. Here virus infection is proposed as a possible candidate for maintaining genotypic diversity in their host plants.Methods
The effects of White clover mosaic virus (WClMV) on the performance and development of different Trifolium repens genotypes were analysed and the G × E interactions were examined with respect to genotype-specific plant responses to WClMV infection. Thus, the environment is defined as the presence or absence of the virus.Key Results
WClMV had a negative effect on plant performance as shown by a decrease in biomass and number of ramets. These effects of virus infection differ greatly among host genotypes, representing a strong G × E interaction. Moreover, the relative fitness and associated ranking of genotypes changed significantly between control and virus treatments. This shift in relative fitness among genotypes suggests the potential for WClMV to provoke differential selection on T. repens genotypes, which may lead to negative frequency-dependent selection in host populations.Conclusions
The apparent G × E interaction and evident repercussions for relative fitness reported in this study stress the importance of viruses for ecological and evolutionary processes and suggest an important role for viruses in shaping population dynamics and micro-evolutionary processes. 相似文献2.
Background and Aims
Plant genotypic mixtures have the potential to increase yield stability in variable, often unpredictable environments, yet knowledge of the specific mechanisms underlying enhanced yield stability remains limited. Field studies are constrained by environmental conditions which cannot be fully controlled and thus reproduced. A suitable model system would allow reproducible experiments on processes operating within crop genetic mixtures.Methods
Phenotypically dissimilar genotypes of Arabidopsis thaliana were grown in monocultures and mixtures under high levels of competition for abiotic resources. Seed production, flowering time and rosette size were recorded.Key Results
Mixtures achieved high yield stability across environments through compensatory interactions. Compensation was greatest when plants were under high levels of heat and nutrient stress. Competitive ability and mixture performance were predictable from above-ground phenotypic traits even though below-ground competition appeared to be more intense.Conclusions
This study indicates that the mixing ability of plant genotypes can be predicted from their phenotypes expressed in a range of relevant environments, and implies that a phenotypic screen of genotypes could improve the selection of suitable components of genotypic mixtures in agriculture intended to be resilient to environmental stress. 相似文献3.
Background and Aims
Experimental crosses between the diploid woodland strawberry (Fragaria vesca L.) and the octoploid garden strawberry (F. × ananassa Duch.) can lead to the formation of viable hybrids. However, the extent of such hybrid formation under natural conditions is unknown, but is of fundamental interest and importance in the light of the potential future cultivation of transgenic strawberries. A hybrid survey was therefore conducted in the surroundings of ten farms in Switzerland and southern Germany, where strawberries have been cultivated for at least 10 years and where wild strawberries occur in the close vicinity.Methods
In 2007 and 2008, 370 wild F. vesca plants were sampled at natural populations around farms and analysed with microsatellite markers. In 2010, natural populations were revisited and morphological traits of 3050 F. vesca plants were inspected. DNA contents of cell nuclei of morphologically deviating plants were estimated by flow cytometry to identify hybrids. As controls, 50 hybrid plants from interspecific hand-crosses were analysed using microsatellite analysis and DNA contents of cell nuclei were estimated by flow cytometry.Key Results
None of the wild samples collected in 2007 and 2008 contained F. × ananassa microsatellite markers, while all hybrids from hand-crosses clearly contained markers of both parent species. Morphological inspection of wild populations carried out in 2010 and subsequent flow cytometry of ten morphologically deviating plants revealed no hybrids.Conclusions
Hybrid formation or hybrid establishment in natural populations in the survey area is at best a rare event. 相似文献4.
5.
Albert B Raquin C Prigent M Nadot S Brisset F Yang M Ressayre A 《Annals of botany》2011,107(8):1421-1426
Background and Aims
The tam (tardy asynchronous meiosis) mutant of Arabidopsis thaliana, which exhibits a modified cytokinesis with a switch from simultaneous to successive cytokinesis, was used to perform a direct test of the implication of cytokinesis in aperture-pattern ontogeny of angiosperm pollen grains. The aperture pattern corresponds to the number and arrangement of apertures (areas of the pollen wall permitting pollen tube germination) on the surface of the pollen grain.Methods
A comparative analysis of meiosis and aperture distribution was performed in two mutant strains of arabidopsis: quartet and quartet-tam.Key Results
While the number of apertures is not affected in the quartet-tam mutant, the arrangement of the three apertures is modified compared with the quartet, resulting in a different aperture pattern.Conclusions
These results directly demonstrate the relationship between the type of sporocytic cytokinesis and pollen aperture-pattern ontogeny. 相似文献6.
Thomas Miedaner Yusheng Zhao Manje Gowda C Friedrich H Longin Viktor Korzun Erhard Ebmeyer Ebrahim Kazman Jochen C Reif 《BMC genomics》2013,14(1)
Background
Septoria tritici blotch is an important leaf disease of European winter wheat. In our survey, we analyzed Septoria tritici blotch resistance in field trials with a large population of 1,055 elite hybrids and their 87 parental lines. Entries were fingerprinted with the 9 k SNP array. The accuracy of prediction of Septoria tritici blotch resistance achieved with different genome-wide mapping approaches was evaluated based on robust cross validation scenarios.Results
Septoria tritici blotch disease severities were normally distributed, with genotypic variation being significantly (P < 0.01) larger than zero. The cross validation study revealed an absence of large effect QTL for additive and dominance effects. Application of genomic selection approaches particularly designed to tackle complex agronomic traits allowed to double the accuracy of prediction of Septoria tritici blotch resistance compared to calculation methods suited to detect QTL with large effects.Conclusions
Our study revealed that Septoria tritici blotch resistance in European winter wheat is controlled by multiple loci with small effect size. This suggests that the currently achieved level of resistance in this collection is likely to be durable, as involvement of a high number of genes in a resistance trait reduces the risk of the resistance to be overcome by specific pathogen isolates or races.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-14-858) contains supplementary material, which is available to authorized users. 相似文献7.
Background and Aims
Despite the intense interest in phenological adaptation to environmental change, the fundamental character of natural variation in germination is almost entirely unknown. Specifically, it is not known whether different genotypes within a species are germination specialists to particular conditions, nor is it known what physiological mechanisms of germination regulation vary in natural populations and how they are associated with responses to particular environmental factors.Methods
We used a set of recombinant inbred genotypes of Arabidopsis thaliana, in which linkage disequilibrium has been disrupted over seven generations, to test for genetic variation and covariation in germination responses to distinct environmental factors. We then examined physiological mechanisms associated with those responses, including seed-coat permeability and sensitivity to the phytohormones gibberellic acid (GA) and abscisic acid (ABA).Key Results
Genetic variation for germination was environment-dependent, but no evidence for specialization of germination to different conditions was found. Hormonal sensitivities also exhibited significant genetic variation, but seed-coat properties did not. GA sensitivity was associated with germination responses to multiple environmental factors, but seed-coat permeability and ABA sensitivity were associated with specific germination responses, suggesting that an evolutionary change in GA sensitivity could affect germination in multiple environments, but that of ABA sensitivity may affect germination under more restricted conditions.Conclusions
The physiological mechanisms of germination responses to specific environmental factors therefore can influence the ability to adapt to diverse seasonal environments encountered during colonization of new habitats or with future predicted climate change. 相似文献8.
Zixiang Wen Ruijuan Tan Jiazheng Yuan Carmille Bales Wenyan Du Shichen Zhang Martin I Chilvers Cathy Schmidt Qijian Song Perry B Cregan Dechun Wang 《BMC genomics》2014,15(1)
Background
Sudden death syndrome (SDS) is a serious threat to soybean production that can be managed with host plant resistance. To dissect the genetic architecture of quantitative resistance to the disease in soybean, two independent association panels of elite soybean cultivars, consisting of 392 and 300 unique accessions, respectively, were evaluated for SDS resistance in multiple environments and years. The two association panels were genotyped with 52,041 and 5,361 single nucleotide polymorphisms (SNPs), respectively. Genome-wide association mapping was carried out using a mixed linear model that accounted for population structure and cryptic relatedness.Result
A total of 20 loci underlying SDS resistance were identified in the two independent studies, including 7 loci localized in previously mapped QTL intervals and 13 novel loci. One strong peak of association on chromosome 18, associated with all disease assessment criteria across the two panels, spanned a physical region of 1.2 Mb around a previously cloned SDS resistance gene (GmRLK18-1) in locus Rfs2. An additional variant independently associated with SDS resistance was also found in this genomic region. Other peaks were within, or close to, sequences annotated as homologous to genes previously shown to be involved in plant disease resistance. The identified loci explained an average of 54.5% of the phenotypic variance measured by different disease assessment criteria.Conclusions
This study identified multiple novel loci and refined the map locations of known loci related to SDS resistance. These insights into the genetic basis of SDS resistance can now be used to further enhance durable resistance to SDS in soybean. Additionally, the associations identified here provide a basis for further efforts to pinpoint causal variants and to clarify how the implicated genes affect SDS resistance in soybean.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-809) contains supplementary material, which is available to authorized users. 相似文献9.
10.
Background and Aims
Successful establishment of newly formed polyploid species depends on several interlinked genetic and ecological factors. These include genetic diversity within and among individuals, chromosome behaviour and fertility, novel phenotypes resulting from novel genomic make-up and expression, intercytotypic and interspecific competition, and adaptation to distinct habitats. The allotetraploid rock fern Asplenium majoricum is known from one small population in Valencia, Spain, and several larger populations on the Balearic island of Majorca. In Valencia, it occurs sympatrically with its diploid parents, A. fontanum subsp. fontanum and A. petrarchae subsp. bivalens, and their diploid hybrid A. × protomajoricum. This highly unusual situation allowed the study of polyploid genetic diversity and its relationship to the formation and establishment of nascent polyploid lineages.Methods
Genetic variation for isozyme and chloroplast DNA markers was determined for A. majoricum and A. × protomajoricum sampled thoroughly from known sites in Majorca and Valencia. Results were compared with variation determined previously for the diploid parent taxa.Key Results
A highly dynamic system with recurring diploid hybrid and allotetraploid formation was discovered. High diversity in the small Valencian A. majoricum population indicates multiple de novo origins from diverse parental genotypes, but most of these lineages become extinct without becoming established. The populations on Majorca most probably represent colonization(s) from Valencia rather than an in situ origin. Low genetic diversity suggests that this colonization may have occurred only once.Conclusions
There is a striking contrast in success of establishment of the Majorcan and Valencian populations of A. majoricum. Chance founding of populations in a habitat where neither A. fontanum subsp. fontanum nor A. petrarchae subsp. bivalens occurs appears to have been a key factor enabling the establishment of A. majoricum on Majorca. Successful establishment of this polyploid is probably dependent on geographic isolation from diploid progenitor competition. 相似文献11.
12.
Kenderesová L Stanová A Pavlovkin J Durisová E Nadubinská M Ciamporová M Ovecka M 《Annals of botany》2012,110(2):445-459
Background and Aims
Uptake of heavy metals by plant root cells depends on electro-physiological parameters of the plasma membrane. In this study, responses of the plasma membrane in root cells were analysed where early reactions to the metal ion-induced stress are localized. Three different Arabidopsis species with diverse strategies of their adaptation to heavy metals were compared: sensitive Arabidopsis thaliana and tolerant A. halleri and A. arenosa.Methods
Plants of A. thaliana Col-0 ecotype and plants of A. arenosa and A. halleri originating from natural metallicolous populations were exposed to high concentrations of Zn2+. Plants were tested for root growth rate, cellular tolerance, plant morphology and cell death in the root apex. In addition, the membrane potential (EM) of mature cortical root cells and changes in the pH of the liquid culture media were measured.Key Results
Primary roots of A. halleri and A. arenosa plants grew significantly better at increased Zn2+ concentrations than A. thaliana plants. Elevated Zn2+ concentrations in the culture medium induced rapid changes in EM. The reaction was species-specific and concentration-dependent. Arabidopsis halleri revealed the highest insensitivity of the plasma membrane and the highest survival rate under prolonged treatment with extra-high concentrations. Plants were able to effectively adjust the pH in the control, but much less at Zn2+-induced lower pH.Conclusions
The results indicate a similar mode of early reaction to Zn2+, but with different extent in tolerant and sensitive species of Arabidopsis. The sensitivity of A. thaliana and a high tolerance of A. halleri and A. arenosa were demonstrated. Plasma membrane depolarization was lowest in the hyperaccumulator A. halleri and highest in A. thaliana. This indicates that rapid membrane voltage changes are an excellent tool to monitor the effects of heavy metals. 相似文献13.
Water stress-induced xylem hydraulic failure is a causal factor of tree mortality in beech and poplar 总被引:1,自引:0,他引:1
Têtè Sévérien Barigah Olivia Charrier Marie Douris Marc Bonhomme Stéphane Herbette Thierry Améglio Régis Fichot Frank Brignolas Hervé Cochard 《Annals of botany》2013,112(7):1431-1437
Background and Aims
Extreme water stress episodes induce tree mortality, but the physiological mechanisms causing tree death are still poorly understood. This study tests the hypothesis that a potted tree''s ability to survive extreme monotonic water stress is determined by the cavitation resistance of its xylem tissue.Methods
Two species were selected with contrasting cavitation resistance (beech and poplar), and potted juvenile trees were exposed to a range of water stresses, causing up to 100 % plant death.Key Results
The lethal dose of water stress, defined as the xylem pressure inducing 50 % mortality, differed sharply across species (1·75 and 4·5 MPa in poplar and beech, respectively). However, the relationships between tree mortality and the degree of cavitation in the stems were similar, with mortality occurring suddenly when >90 % cavitation had occurred.Conclusions
Overall, the results suggest that cavitation resistance is a causal factor of tree mortality under extreme drought conditions. 相似文献14.
Background and Aims
Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots.Methods
Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen.Key Results
Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant.Conclusions
The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks. 相似文献15.
16.
Hippolyte I Jenny C Gardes L Bakry F Rivallan R Pomies V Cubry P Tomekpe K Risterucci AM Roux N Rouard M Arnaud E Kolesnikova-Allen M Perrier X 《Annals of botany》2012,109(5):937-951
Background and Aims
The production of triploid banana and plantain (Musa spp.) cultivars with improved characteristics (e.g. greater disease resistance or higher yield), while still preserving the main features of current popular cultivars (e.g. taste and cooking quality), remains a major challenge for Musa breeders. In this regard, breeders require a sound knowledge of the lineage of the current sterile triploid cultivars, to select diploid parents that are able to transmit desirable traits, together with a breeding strategy ensuring final triploidization and sterility. Highly polymorphic single sequence repeats (SSRs) are valuable markers for investigating phylogenetic relationships.Methods
Here, the allelic distribution of each of 22 SSR loci across 561 Musa accessions is analysed.Key Results and Conclusions
We determine the closest diploid progenitors of the triploid ‘Cavendish’ and ‘Gros Michel’ subgroups, valuable information for breeding programmes. Nevertheless, in establishing the likely monoclonal origin of the main edible triploid banana subgroups (i.e. ‘Cavendish’, ‘Plantain’ and ‘Mutika-Lujugira’), we postulated that the huge phenotypic diversity observed within these subgroups did not result from gamete recombination, but rather from epigenetic regulations. This emphasizes the need to investigate the regulatory mechanisms of genome expression on a unique model in the plant kingdom. We also propose experimental standards to compare additional and independent genotyping data for reference. 相似文献17.
Background and Aims
The ecological, evolutionary and genetic bases of population differentiation in a variable environment are often related to the selection pressures that plants experience. We compared differences in several growth- and defence-related traits in two isolated populations of Acacia raddiana trees from sites at either end of an extreme environmental gradient in the Negev desert.Methods
We used random amplified polymorphic DNA (RAPD) to determine the molecular differences between populations. We grew plants under two levels of water, three levels of nutrients and three levels of herbivory to test for phenotypic plasticity and adaptive phenotypic plasticity.Key Results
The RAPD analyses showed that these populations are highly genetically differentiated. Phenotypic plasticity in various morphological traits in A. raddiana was related to patterns of population genetic differentiation between the two study sites. Although we did not test for maternal effects in these long-lived trees, significant genotype × environment (G × E) interactions in some of these traits indicated that such plasticity may be adaptive.Conclusions
The main selection pressure in this desert environment, perhaps unsurprisingly, is water. Increased water availability resulted in greater growth in the southern population, which normally receives far less rain than the northern population. Even under the conditions that we defined as low water and/or nutrients, the performance of the seedlings from the southern population was significantly better, perhaps reflecting selection for these traits. Consistent with previous studies of this genus, there was no evidence of trade-offs between physical and chemical defences and plant growth parameters in this study. Rather, there appeared to be positive correlations between plant size and defence parameters. The great variation in several traits in both populations may result in a diverse potential for responding to selection pressures in different environments. 相似文献18.
Patel D Power JB Anthony P Badakshi F Pat Heslop-Harrison JS Davey MR 《Annals of botany》2011,108(5):809-819
Background and Aims
The genus Nicotiana includes diploid and tetraploid species, with complementary ecological, agronomic and commercial characteristics. The species are of economic value for tobacco, as ornamentals, and for secondary plant-product biosynthesis. They show substantial differences in disease resistance because of their range of secondary products. In the last decade, sexual hybridization and transgenic technologies have tended to eclipse protoplast fusion for gene transfer. Somatic hybridization was exploited in the present investigation to generate a new hybrid combination involving two sexually incompatible tetraploid species. The somatic hybrid plants were characterized using molecular, molecular cytogenetic and phenotypic approaches.Methods
Mesophyll protoplasts of the wild fungus-resistant species N. debneyi (2n = 4x = 48) were electrofused with those of the ornamental interspecific sexual hybrid N. × sanderae (2n = 2x = 18). From 1570 protoplast-derived cell colonies selected manually in five experiments, 580 tissues were sub-cultured to shoot regeneration medium. Regenerated plants were transferred to the glasshouse and screened for their morphology, chromosomal composition and disease resistance.Key Results
Eighty-nine regenerated plants flowered; five were confirmed as somatic hybrids by their intermediate morphology compared with parental plants, cytological constitution and DNA-marker analysis. Somatic hybrid plants had chromosome complements of 60 or 62. Chromosomes were identified to parental genomes by genomic in situ hybridization and included all 18 chromosomes from N. × sanderae, and 42 or 44 chromosomes from N. debneyi. Four or six chromosomes of one ancestral genome of N. debneyi were eliminated during culture of electrofusion-treated protoplasts and plant regeneration. Both chloroplasts and mitochondria of the somatic hybrid plants were probably derived from N. debneyi. All somatic hybrid plants were fertile. In contrast to parental plants of N. × sanderae, the seed progeny of somatic hybrid plants were resistant to infection by Peronospora tabacina, a trait introgressed from the wild parent, N. debneyi.Conclusions
Sexual incompatibility between N. × sanderae and N. debneyi was circumvented by somatic hybridization involving protoplast fusion. Asymmetrical nuclear hybridity was seen in the hybrids with loss of chromosomes, although importantly, somatic hybrids were fertile and stable. Expression of fungal resistance makes these somatic hybrids extremely valuable germplasm in future breeding programmes in ornamental tobacco. 相似文献19.