The objective of this study was to answer the question of how the deacclimation process affects frost tolerance, photosynthetic efficiency, brassinosteroid (BR) homeostasis and BRI1 expression of winter oilseed rape. A comparative study was conducted on cultivars with different agronomic and physiological traits. The deacclimation process can occur when there are periods of higher temperatures, particularly in the late autumn or winter. This interrupts the process of the acclimation (hardening) of winter crops to low temperatures, thus reducing their frost tolerance and becoming a serious problem for agriculture. The experimental model included plants that were non-acclimated, cold acclimated (at 4 °C) and deacclimated (at 16 °C/9 °C, one week). We found that deacclimation tolerance (maintaining a high frost tolerance despite warm deacclimating periods) was a cultivar-dependent trait. Some of the cultivars developed a high frost tolerance after cold acclimation and maintained it after deacclimation. However, there were also cultivars that had a high frost tolerance after cold acclimation but lost some of it after deacclimation (the cultivars that were more susceptible to deacclimation). Deacclimation reversed the changes in the photosystem efficiency that had been induced by cold acclimation, and therefore, measuring the different signals associated with photosynthetic efficiency (based on prompt and delayed chlorophyll fluorescence) of plants could be a sensitive tool for monitoring the deacclimation process (and possible changes in frost tolerance) in oilseed rape. Higher levels of BR were characteristic of the better frost-tolerant cultivars in both the cold-acclimated and deacclimated plants. The relative expression of the BRI1 transcript (encoding the BR-receptor protein) was lower after cold acclimation and remained low in the more frost-tolerant cultivars after deacclimation. The role of brassinosteroids in oilseed rape acclimation/deacclimation is briefly discussed.
- Klíčová slova
- brassinosteroid insensitive 1, brassinosteroids, dehardening, delayed chlorophyll fluorescence, frost tolerance, homocastasterone, photosystem I, photosystem II, prompt chlorophyll fluorescence, stress tolerance,
- MeSH
- aklimatizace fyziologie MeSH
- Brassica napus * genetika MeSH
- brassinosteroidy MeSH
- fotosyntéza MeSH
- homeostáza MeSH
- nízká teplota MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- brassinosteroidy MeSH
Phoma stem canker (caused by the ascomycetes Leptosphaeria maculans and Leptosphaeria biglobosa) is an important disease of oilseed rape. Its effect on endophyte communities in roots and shoots and the potential of endophytes to promote growth and control diseases of oilseed rape (OSR) was investigated. Phoma stem canker had a large effect especially on fungal but also on bacterial endophyte communities. Dominant bacterial genera were Pseudomonas, followed by Enterobacter, Serratia, Stenotrophomonas, Bacillus and Staphylococcus. Achromobacter, Pectobacter and Sphingobacterium were isolated only from diseased plants, though in very small numbers. The fungal genera Cladosporium, Botrytis and Torula were dominant in healthy plants whereas Alternaria, Fusarium and Basidiomycetes (Vishniacozyma, Holtermaniella, Bjerkandera/Thanatephorus) occurred exclusively in diseased plants. Remarkably, Leptosphaeria biglobosa could be isolated in large numbers from shoots of both healthy and diseased plants. Plant growth promoting properties (antioxidative activity, P-solubilisation, production of phytohormones and siderophores) were widespread in OSR endophytes. Although none of the tested bacterial endophytes (Achromobacter, Enterobacter, Pseudomonas, Serratia and Stenotrophomonas) promoted growth of oilseed rape under P-limiting conditions or controlled Phoma disease on oilseed rape cotyledons, they significantly reduced incidence of Sclerotinia disease. In the field, a combined inoculum consisting of Achromobacter piechaudii, two pseudomonads and Stenotrophomonas rhizophila tendencially increased OSR yield and reduced Phoma stem canker.
- MeSH
- Achromobacter genetika růst a vývoj MeSH
- Ascomycota genetika růst a vývoj MeSH
- Brassica napus genetika růst a vývoj mikrobiologie MeSH
- endofyty genetika růst a vývoj MeSH
- kořeny rostlin genetika mikrobiologie MeSH
- mykobiom genetika MeSH
- nemoci rostlin genetika mikrobiologie MeSH
- odolnost vůči nemocem genetika MeSH
- Phoma genetika růst a vývoj MeSH
- Stenotrophomonas genetika růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Rate of photosynthesis and related plant carbohydrate status are crucial factors affecting plant vigor. Sugars providing carbon and energy sources serve also as important signaling molecules governing plant growth and development through a complex regulatory network. These facts are often neglected when mixotrophic cultivation of plants in vitro is used, where artificial exogenous sugar supply hinders studies of metabolism as well as sugar-driven developmental processes. We compared the growth, selected gas-exchange parameters and sugar metabolism characteristics in four model plants, potato (Solanum tuberosum 'Lada'), tobacco (Nicotiana tabacum 'Samsun'), rapeseed (Brassica napus 'Asgard') and strawberry (Fragaria vesca), under both photomixotrophic (PM) and photoautotrophic (PA) conditions. To ensure PA conditions, we used our improved sun caps that serve as gas and light permeable covers for cultivation vessels. We found bigger biomass accumulation, larger leaf areas, higher stomatal conductance and higher instantaneous water use efficiency and lower root sugar contents in PA plants compared to PM ones. However, for other characteristics (root biomass, root/shoot ratio, pigment contents, leaf sugar and starch levels and transpiration rates), a strong species-dependent reactions to the exogenous sugar supply was noted, which does not allow to create a general view on the overall impact of PM nutrition under in vitro conditions.
- MeSH
- Brassica napus genetika metabolismus fyziologie MeSH
- fotosyntéza genetika fyziologie MeSH
- jahodník genetika metabolismus fyziologie MeSH
- kořeny rostlin genetika metabolismus fyziologie MeSH
- listy rostlin genetika metabolismus fyziologie MeSH
- tabák genetika metabolismus fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Cytokinin is a negative regulator of root growth, and a reduction of the cytokinin content or signalling causes the formation a larger root system in model plants, improves their growth under drought and nutrient limitation and causes increased accumulation of elements in the shoot. Roots are an important but understudied target of plant breeding. Here we have therefore explored whether root enhancement by lowering the cytokinin content can also be achieved in oilseed rape (Brassica napus L.) plants. RESULTS: Transgenic plants overexpressing the CKX2 gene of Arabidopsis thaliana encoding a cytokinin-degrading cytokinin oxidase/dehydrogenase showed higher CKX activity and a strongly reduced cytokinin content. Cytokinin deficiency led to the formation of a larger root system under different growth conditions, which was mainly due to an increased number of lateral and adventitious roots. In contrast, shoot growth was comparable to wild type, which caused an enhanced root-to-shoot ratio. Transgenic plants accumulated in their leaves higher concentrations of macro- and microelements including P, Ca, Mg, S, Zn, Cu, Mo and Mn. They formed more chlorophyll under Mg- and S-deficiency and accumulated a larger amount of Cd and Zn from contaminated medium and soil. CONCLUSIONS: These findings demonstrate the usefulness of ectopic CKX gene expression to achieve root enhancement in oilseed rape and underpin the functional relevance of a larger root system. Furthermore, the lack of major developmental consequences on shoot growth in cytokinin-deficient oilseed rape indicates species-specific differences of CKX gene and/or cytokinin action.
- Klíčová slova
- Brassica napus, Cytokinin, Cytokinin oxidase/dehydrogenase, Leaf mineral enrichment, Phytoremediation, Plant growth, Root enhancement,
- MeSH
- biodegradace * MeSH
- Brassica napus genetika růst a vývoj metabolismus MeSH
- chlorofyl analýza metabolismus MeSH
- cytokininy genetika metabolismus MeSH
- geneticky modifikované rostliny MeSH
- kadmium analýza metabolismus MeSH
- kořeny rostlin růst a vývoj metabolismus MeSH
- listy rostlin chemie metabolismus MeSH
- oxidoreduktasy genetika metabolismus MeSH
- půda chemie MeSH
- zinek analýza metabolismus MeSH
- živiny analýza metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl MeSH
- cytokinin oxidase MeSH Prohlížeč
- cytokininy MeSH
- kadmium MeSH
- oxidoreduktasy MeSH
- půda MeSH
- zinek MeSH
BACKGROUND AND AIMS: Brassica napus (AACC, 2n = 38, oilseed rape) is a relatively recent allotetraploid species derived from the putative progenitor diploid species Brassica rapa (AA, 2n = 20) and Brassica oleracea (CC, 2n = 18). To determine the influence of intensive breeding conditions on the evolution of its genome, we analysed structure and copy number of rDNA in 21 cultivars of B. napus, representative of genetic diversity. METHODS: We used next-generation sequencing genomic approaches, Southern blot hybridization, expression analysis and fluorescence in situ hybridization (FISH). Subgenome-specific sequences derived from rDNA intergenic spacers (IGS) were used as probes for identification of loci composition on chromosomes. KEY RESULTS: Most B. napus cultivars (18/21, 86 %) had more A-genome than C-genome rDNA copies. Three cultivars analysed by FISH ('Darmor', 'Yudal' and 'Asparagus kale') harboured the same number (12 per diploid set) of loci. In B. napus 'Darmor', the A-genome-specific rDNA probe hybridized to all 12 rDNA loci (eight on the A-genome and four on the C-genome) while the C-genome-specific probe showed weak signals on the C-genome loci only. Deep sequencing revealed high homogeneity of arrays suggesting that the C-genome genes were largely overwritten by the A-genome variants in B. napus 'Darmor'. In contrast, B. napus 'Yudal' showed a lack of gene conversion evidenced by additive inheritance of progenitor rDNA variants and highly localized hybridization signals of subgenome-specific probes on chromosomes. Brassica napus 'Asparagus kale' showed an intermediate pattern to 'Darmor' and 'Yudal'. At the expression level, most cultivars (95 %) exhibited stable A-genome nucleolar dominance while one cultivar ('Norin 9') showed co-dominance. CONCLUSIONS: The B. napus cultivars differ in the degree and direction of rDNA homogenization. The prevalent direction of gene conversion (towards the A-genome) correlates with the direction of expression dominance indicating that gene activity may be needed for interlocus gene conversion.
- Klíčová slova
- Brassica napus, allopolyploidy, chromosome evolution, gene conversion, rDNA,
- MeSH
- Brassica napus genetika MeSH
- genetická variace genetika MeSH
- genetické lokusy genetika MeSH
- genová konverze genetika MeSH
- hybridizace in situ fluorescenční MeSH
- ribozomální DNA genetika MeSH
- Southernův blotting MeSH
- stanovení celkové genové exprese MeSH
- vysoce účinné nukleotidové sekvenování MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ribozomální DNA MeSH
Nitrogen (N) efficiency of winter oilseed rape (Brassica napus L.) line-cultivars (cvs.), defined as high grain yield under N limitation, has been primarily attributed to maintained N uptake during reproductive growth (N uptake efficiency) in combination with delayed senescence of the older leaves accompanied with maintained photosynthetic capacity (functional stay-green). However, it is not clear whether genotypic variation in N starvation-induced leaf senescence is due to leaf-inherent factors and/or governed by root-mediated signals. Therefore, the N-efficient and stay-green cvs. NPZ-1 and Apex were reciprocally grafted with the N-inefficient and early-senescing cvs. NPZ-2 and Capitol, respectively and grown in hydroponics. The senescence status of older leaves after 12 days of N starvation assessed by SPAD, photosynthesis and the expression of the senescence-specific cysteine protease gene SAG12-1 revealed that the stay-green phenotype of the cvs. NPZ-1 and Apex under N starvation was primarily under the control of leaf-inherent factors. The same four cultivars were submitted to N starvation for up to 12 days in a time-course experiment. The specific leaf contents of biologically active and inactive cytokinins (CKs) and the expression of genes involved in CK homeostasis revealed that under N starvation leaves of early-senescing cultivars were characterized by inactivation of biologically active CKs, whereas in stay-green cultivars synthesis, activation, binding of and response to biologically active CKs were favoured. These results suggest that the homeostasis of biologically active CKs was the predominant leaf-inherent factor for cultivar differences in N starvation-induced leaf senescence and thus N efficiency.
- Klíčová slova
- Brassica napus, cytokinins, genotypic differences, leaf senescence, nitrogen efficiency, nitrogen starvation, reciprocal grafting, stay-green.,
- MeSH
- Brassica napus genetika metabolismus MeSH
- chlorofyl metabolismus MeSH
- cytokininy metabolismus MeSH
- dusík metabolismus MeSH
- fotosyntéza MeSH
- glukosidy metabolismus MeSH
- homeostáza MeSH
- kořeny rostlin metabolismus MeSH
- listy rostlin enzymologie růst a vývoj metabolismus MeSH
- proteasy metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- roční období * MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- signální transdukce genetika MeSH
- zeatin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chlorofyl MeSH
- cytokininy MeSH
- dusík MeSH
- glukosidy MeSH
- proteasy MeSH
- rostlinné proteiny MeSH
- zeatin-O-glucoside MeSH Prohlížeč
- zeatin MeSH
The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS (ARF5)-dependent auxin signalling and auxin transport. This MONOPTEROS-dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate that auxin-dependent cell specification during embryo development requires balanced auxin transport involving both influx and efflux mechanisms, and that this transport is maintained by a positive transcriptional feedback on auxin signalling.
- Klíčová slova
- AUX1, Arabidopsis thaliana embryogenesis, Auxin transport, Brassica napus, LIKE-AUX1 (LAX), MONOPTEROS (ARF5), Microspore, PIN,
- MeSH
- Arabidopsis embryologie genetika metabolismus MeSH
- biologický transport genetika fyziologie MeSH
- Brassica napus embryologie genetika metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- rostlinné proteiny metabolismus MeSH
- semena rostlinná cytologie metabolismus MeSH
- signální transdukce genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- rostlinné proteiny MeSH
Cytokinin (CK) signalling is known to play key roles in the regulation of plant growth and development, crop yields, and tolerance to both abiotic stress and pathogen defences, but the mechanisms involved are poorly characterized in dicotyledonous crops. Here the identification and functional characterization of sensor histidine kinases homologous to Arabidopsis CK receptors AHK2 and AHK3 in winter oilseed rape are presented. Five CHASE-containing His kinases were identified in Brassica napus var. Tapidor (BnCHK1-BnCHK5) by heterologous hybridization of its genomic library with gene-specific probes from Arabidopsis. The identified bacterial artificial chromosome (BAC) clones were fingerprinted and representative clones in five distinct groups were sequenced. Using a bioinformatic approach and cDNA cloning, the precise gene and putative protein domain structures were determined. Based on phylogenetic analysis, four AHK2 (BnCHK1-BnCHK4) homologues and one AHK3 (BnCHK5) homologue were defined. It is further suggested that BnCHK1 and BnCHK3, and BnCHK5 are orthologues of AHK2 and AHK3, originally from the B. rapa A genome, respectively. BnCHK1, BnCHK3, and BnCHK5 displayed high affinity for trans-zeatin (1-3nM) in a live-cell competitive receptor assay, but not with other plant hormones (indole acetic acid, GA3, and abscisic acid), confirming the prediction that they are genuine CK receptors. It is shown that BnCHK1 and BnCHK3, and BnCHK5 display distinct preferences for various CK bases and metabolites, characteristic of their AHK counterparts, AHK2 and AHK3, respectively. Interestingly, the AHK2 homologues could be divided into two subfamilies (BnCHK1/BnCK2 and BnCHK3/BnCHK4) that differ in putative transmembrane domain topology and CK binding specificity, thus implying potential functional divergence.
- Klíčová slova
- CHASE-containing His kinase, E. coli-based live-cell competitive receptor assay, JBnB library, gene structure, modular protein architecture, phylogenetic analysis,
- MeSH
- Brassica napus genetika metabolismus MeSH
- fylogeneze MeSH
- histidinkinasa MeSH
- molekulární sekvence - údaje MeSH
- proteinkinasy genetika metabolismus MeSH
- proteiny huseníčku MeSH
- regulace genové exprese u rostlin * MeSH
- rostlinné proteiny chemie genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- signální transdukce MeSH
- terciární struktura proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- AHK2 protein, Arabidopsis MeSH Prohlížeč
- AHK3 protein, Arabidopsis MeSH Prohlížeč
- histidinkinasa MeSH
- proteinkinasy MeSH
- proteiny huseníčku MeSH
- rostlinné proteiny MeSH
Antimicrobial decapeptide anoplin was tested for its antifungal activity against plant pathogen Leptosphaeria maculans and protection of Brassica napus plants from disease. To reveal the mode of action of the peptide, a natural form of anoplin amidated on C-terminus (ANP-NH2), and its carboxylated analog (ANP-OH) were used in the study. We demonstrated strong antifungal activity of anoplin in vitro regardless C-terminus modification. In addition we show that both ANP-NH2 and ANP-OH induce expression of defence genes in B. napus and protects plants from L. maculans infection. The results indicate that the amidation of anoplin is not essential for its antifungal and plant defence stimulating activities.
- Klíčová slova
- Anoplin, Antifungal, Antimicrobial peptide, Brassica napus, Leptosphaeria maculans,
- MeSH
- amidy chemie farmakologie MeSH
- antifungální látky chemie farmakologie MeSH
- Ascomycota účinky léků MeSH
- Brassica napus genetika mikrobiologie MeSH
- kationické antimikrobiální peptidy chemie farmakologie MeSH
- nemoci rostlin mikrobiologie prevence a kontrola MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- vosí jedy chemie farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- amidy MeSH
- anoplin MeSH Prohlížeč
- antifungální látky MeSH
- kationické antimikrobiální peptidy MeSH
- vosí jedy MeSH
