During plant growth and defense, cell cycle activity needs to be coordinated with cell wall integrity. Little is known about how this coordination is achieved. Here, we investigated coordination in Arabidopsis thaliana seedlings by studying the impact of cell wall damage (CWD, caused by cellulose biosynthesis inhibition) on cytokinin homeostasis, cell cycle gene expression and cell shape in root tips. CWD inhibited cell cycle gene expression and increased transition zone cell width in an osmosensitive manner. These results were correlated with CWD-induced, osmosensitive changes in cytokinin homeostasis. Expression of CYTOKININ OXIDASE/DEHYDROGENASE 2 and 3 (CKX2, CKX3), which encode cytokinin-degrading enzymes, was induced by CWD and reduced by osmoticum treatment. In nitrate reductase1 nitrate reductase2 (nia1 nia2) seedlings, CKX2 and CKX3 transcript levels were not increased and cell cycle gene expression was not repressed by CWD. Moreover, established CWD-induced responses, such as jasmonic acid, salicylic acid and lignin production, were also absent, implying a central role of NIA1/2-mediated processes in regulation of CWD responses. These results suggest that CWD enhances cytokinin degradation rates through a NIA1/2-mediated process, leading to attenuation of cell cycle gene expression.

• MeSH
• Arabidopsis cytologie   účinky léků   genetika   MeSH
• benzamidy farmakologie   MeSH
• biologické modely MeSH
• buněčná stěna účinky léků   metabolismus   MeSH
• buněčný cyklus účinky léků   genetika   MeSH
• cytokininy farmakologie   MeSH
• fenotyp MeSH
• homeostáza účinky léků   MeSH
• kořeny rostlin cytologie   účinky léků   růst a vývoj   MeSH
• messenger RNA genetika   metabolismus   MeSH
• nitrátreduktasa metabolismus   MeSH
• osmóza MeSH
• proteiny huseníčku metabolismus   MeSH
• regulace genové exprese u rostlin * účinky léků   MeSH
• semenáček účinky léků   genetika   MeSH
• sorbitol farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The severity and spatial extent of bark-beetle outbreaks substantially increased in recent decades worldwide. The ongoing controversy about natural forest recovery after these outbreaks highlights the need for individual-based long-term studies, which disentangle processes driving forest regeneration. However, such studies have been lacking. To fill this gap, we followed the fates of 2,552 individual seedlings for 12 years after a large-scale bark-beetle outbreak that caused complete canopy dieback in mountain Norway spruce (Picea abies) forests in southeast Germany. We explore the contribution of advance, disturbance-related, and post-disturbance regeneration to forest recovery. Most seedlings originated directly within the three-year dieback of canopy trees induced by bark-beetle outbreak. After complete canopy dieback, the establishment of new seedlings was minimal. Surprisingly, advance regeneration formed only a minor part of all regeneration. However, because it had the highest survival rate, its importance increased over time. The most important factor influencing the survival of seedlings after disturbance was their height. Survival was further modified by microsite: seedlings established on dead wood survived best, whereas almost all seedlings surrounded by graminoids died. For 5 cm tall seedlings, annual mortality ranged from 20 to 50% according to the rooting microsite. However, for seedlings taller than 50 cm, annual mortality was below 5% at all microsites. While microsite modified seedling mortality, it did not affect seedling height growth. A model of regeneration dynamics based on short-term observations accurately predicts regeneration height growth, but substantially underestimates mortality rate, thus predicting more surviving seedlings than were observed. We found that P. abies forests were able to regenerate naturally even after severe bark-beetle outbreaks owing to advance and particularly disturbance-related regeneration. This, together with microsite-specific mortality, yields structurally and spatially diverse forests. Our study thus highlights the so far unrecognized importance of disturbance-related regeneration for stand recovery after bark-beetle outbreaks.

• MeSH
• brouci fyziologie   MeSH
• býložravci * MeSH
• lesy MeSH
• populační dynamika MeSH
• semenáček fyziologie   MeSH
• smrk fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Německo MeSH

Transporter genes and cytokinins are key targets for crop improvement. These genes are active during the development of the seed and its establishment as a strong sink. However, during germination, the seed transitions to being a source for the developing root and shoot. To determine if the sucrose transporter (SUT), amino acid permease (AAP), Sugar Will Eventually be Exported Transporter (SWEET), cell wall invertase (CWINV), cytokinin biosynthesis (IPT), activation (LOG) and degradation (CKX) gene family members are involved in both the sink and source activities of seeds, we used RT-qPCR to determine the expression of multiple gene family members, and LC-MS/MS to ascertain endogenous cytokinin levels in germinating Pisum sativum L. We show that genes that are actively expressed when the seed is a strong sink during its development, are also expressed when the seed is in the reverse role of being an active source during germination and early seedling growth. Cytokinins were detected in the imbibing seeds and were actively biosynthesised during germination. We conclude that, when the above gene family members are targeted for seed yield improvement, a downstream effect on subsequent seed germination or seedling vigour must be taken into consideration.

• MeSH
• buněčná stěna enzymologie   MeSH
• cytokininy biosyntéza   genetika   MeSH
• hrách setý genetika   růst a vývoj   MeSH
• invertasa biosyntéza   genetika   MeSH
• klíčení genetika   MeSH
• proteiny přenášející monosacharidy biosyntéza   genetika   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin genetika   MeSH
• semena rostlinná genetika   růst a vývoj   MeSH
• semenáček genetika   MeSH
• tandemová hmotnostní spektrometrie MeSH
• transportní systémy aminokyselin biosyntéza   genetika   MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: In seeds, the transition from dormancy to germination is regulated by abscisic acid (ABA) and gibberellins (GAs), and involves chromatin remodelling. Particularly, the repressive mark H3K27 trimethylation (H3K27me3) has been shown to target many master regulators of this transition. DAG1 (DOF AFFECTING GERMINATION1), is a negative regulator of seed germination in Arabidopsis, and directly represses the GA biosynthetic gene GA3ox1 (gibberellin 3-β-dioxygenase 1). We set to investigate the role of DAG1 in seed dormancy and maturation with respect to epigenetic and hormonal control. RESULTS: We show that DAG1 expression is controlled at the epigenetic level through the H3K27me3 mark during the seed-to-seedling transition, and that DAG1 directly represses also the ABA catabolic gene CYP707A2; consistently, the ABA level is lower while the GA level is higher in dag1 mutant seeds. Furthermore, both DAG1 expression and protein stability are controlled by GAs. CONCLUSIONS: Our results point to DAG1 as a key player in the control of the developmental switch between seed dormancy and germination.

• MeSH
• Arabidopsis růst a vývoj   metabolismus   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• gibereliny metabolismus   MeSH
• kyselina abscisová metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• semena rostlinná genetika   růst a vývoj   metabolismus   MeSH
• semenáček genetika   růst a vývoj   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

In higher plants, cell cycle activation in the meristems at germination is essential for the initiation of post-embryonic development. We previously identified the signaling pathways of homeobox transcription factor STIMPY and metabolic sugars as two interacting branches of the regulatory network that is responsible for activating meristematic tissue proliferation in Arabidopsis. In this study, we found that CYCP2;1 is both a direct target of STIMPY transcriptional activation and an early responder to sugar signals. Genetic and molecular studies show that CYCP2;1 physically interacts with three of the five mitotic CDKs in Arabidopsis, and is required for the G2 to M transition during meristem activation. Taken together, our results suggest that CYCP2;1 acts as a permissive control of cell cycle progression during seedling establishment by directly linking genetic control and nutritional cues with the activity of the core cell cycle machinery.

• MeSH
• aktivace transkripce MeSH
• Arabidopsis embryologie   MeSH
• buněčné dělení genetika   MeSH
• cyklin-dependentní kinasy biosyntéza   MeSH
• cykliny biosyntéza   genetika   metabolismus   MeSH
• homeodoménové proteiny genetika   MeSH
• meristém cytologie   embryologie   MeSH
• proliferace buněk MeSH
• proteiny huseníčku biosyntéza   genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné geny MeSH
• sacharosa farmakologie   MeSH
• semenáček genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

The proper timing of flowering is essential for the adaptation of plant species to their ever-changing environments. The central position in a complex regulatory network is occupied by the protein FT, which acts as a florigen. We found that light, following a permissive period of darkness, was essential to induce the floral promoter CrFTL1 and to initiate flowering in seedlings of the short-day plant Chenopodium rubrum L. We also identified two novel CONSTANS-like genes in C. rubrum and observed their rhythmic diurnal and circadian expressions. Strong rhythmicity of expression suggested that the two genes might have been involved in the regulation of photoperiod-dependent processes, despite their inability to complement co mutation in A. thaliana. The CrCOL1 and CrCOL2 genes were downregulated by dark-light transition, regardless of the length of a preceding dark period. The same treatment activated the floral promoter CrFTL1. Light therefore affected CrCOL and CrFTL1 in an opposite manner. Both CrCOL genes and CrFTL1 displayed expression patterns unique among short-day plants. Chenopodium rubrum, the subject of classical physiological studies in the past, is emerging as a useful model for the investigation of flowering at the molecular level.

• MeSH
• Arabidopsis MeSH
• Chenopodium genetika   růst a vývoj   fyziologie   MeSH
• florigen metabolismus   MeSH
• fotoperioda MeSH
• květy růst a vývoj   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• promotorové oblasti (genetika) MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• semenáček růst a vývoj   MeSH
• testy genetické komplementace MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The aim of this study was to determine which species of culturable bacteria are associated with ectomycorrhizae (ECM) of Norway spruce (Picea abies (L.) Karst) in the Sudety Mountains, exposed for years to atmospheric pollutants, acid rain, and climatic stress, and to identify particular species that have adapted to those conditions. Biolog identification was performed on bacterial species from ECM of adult spruce trees and seedlings of stands with low, intermediate, and high forest decline. Bacterial diversity in ECM associated with adult spruce trees, seedlings, and seedlings grown on monoliths was calculated; although the expected values appeared to vary widely, no significant differences among sites were observed. Dendrograms based on the identified bacterial species showed that stands with low forest decline clustered separately from the others. Principal component analysis of the normalized data for ECM-associated species showed a clear separation between stands with high forest decline and stands with low forest decline for seedlings and a less evident separation for adult spruce trees. In conclusion, shifts in ECM-associated culturable bacterial populations seem to be associated with forest decline in Norway spruce stands. Some bacterial species were preferentially associated with mycorrhizal roots depending on the degree of forest decline; this was more evident in seedlings where the species Burkholderia cepacia and Pseudomonas fluorescens were associated with, respectively, ECM of the most damaged stands and those with low forest decline.

• MeSH
• Bacteria genetika   růst a vývoj   izolace a purifikace   MeSH
• ekosystém * MeSH
• kořeny rostlin mikrobiologie   MeSH
• mykorhiza fyziologie   MeSH
• počet mikrobiálních kolonií MeSH
• populační dynamika MeSH
• RNA ribozomální 16S genetika   MeSH
• semenáček mikrobiologie   MeSH
• smrk mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH