The At-Hook Motif Nuclear Localized Protein (AHL) gene family encodes embryophyte-specific nuclear proteins with DNA binding activity. They modulate gene expression and affect various developmental processes in plants. We identify AHL18 (At3G60870) as a developmental modulator of root system architecture and growth. AHL18 is involved in regulation of the length of the proliferation domain and number of dividing cells in the root apical meristem and thereby, cell production. Both primary root growth and lateral root development respond according to AHL18 transcription level. The ahl18 knock-out plants show reduced root systems due to a shorter primary root and a lower number of lateral roots. This change results from a higher number of arrested and non-developing lateral root primordia (LRP) rather than from a decreased LRP initiation. The over-expression of AHL18 results in a more extensive root system, longer primary roots, and increased density of lateral root initiation events. AHL18 is thus involved in the formation of lateral roots at both LRP initiation and their later development. We conclude that AHL18 participates in modulation of root system architecture through regulation of root apical meristem activity, lateral root initiation and emergence; these correspond well with expression pattern of AHL18.
- MeSH
- Arabidopsis genetika růst a vývoj metabolismus MeSH
- AT-hook motivy MeSH
- DNA vazebné proteiny chemie genetika metabolismus MeSH
- kořeny rostlin genetika růst a vývoj metabolismus MeSH
- mutace MeSH
- proteiny huseníčku chemie genetika metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: A water-impermeable testa acts as a barrier to a seed's imbibition, thereby imposing dormancy. The physical and functional properties of the macrosclereids are thought to be critical determinants of dormancy; however, the mechanisms underlying the maintenance of and release from dormancy in pea are not well understood. METHODS: Seeds of six pea accessions of contrasting dormancy type were tested for their ability to imbibe and the permeability of their testa was evaluated. Release from dormancy was monitored following temperature oscillation, lipid removal and drying. Histochemical and microscopic approaches were used to characterize the structure of the testa. KEY RESULTS: The strophiole was identified as representing the major site for the entry of water into non-dormant seeds, while water entry into dormant seeds was distributed rather than localized. The major barrier for water uptake in dormant seeds was the upper section of the macrosclereids, referred to as the 'light line'. Dormancy could be released by thermocycling, dehydration or chloroform treatment. Assays based on either periodic acid or ruthenium red were used to visualize penetration through the testa. Lipids were detected within a subcuticular waxy layer in both dormant and non-dormant seeds. The waxy layer and the light line both formed at the same time as the establishment of secondary cell walls at the tip of the macrosclereids. CONCLUSIONS: The light line was identified as the major barrier to water penetration in dormant seeds. Its outer border abuts a waxy subcuticular layer, which is consistent with the suggestion that the light line represents the interface between two distinct environments - the waxy subcuticular layer and the cellulose-rich secondary cell wall. The mechanistic basis of dormancy break includes changes in the testa's lipid layer, along with the mechanical disruption induced by oscillation in temperature and by a decreased moisture content of the embryo.
- MeSH
- hrách setý * MeSH
- klíčení * MeSH
- semena rostlinná MeSH
- teplota MeSH
- vegetační klid MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
There are various preparatory techniques for light microscopy permitting access to the inner structure of plant body and its development. Minute objects might be processed as whole-mount preparations, while voluminous ones should be separated into smaller pieces. Here we summarize some of the "classical" techniques to cut more voluminous objects into slices and access their inner structure either for simple anatomical analysis or for further processing (e.g., histochemistry, immunohistochemistry, in situ hybridization, enzyme histochemistry).
- MeSH
- barvení a značení metody MeSH
- fixace tkání metody MeSH
- histocytochemie metody MeSH
- histocytologické preparační techniky metody MeSH
- mikroskopie metody MeSH
- mikrotomie metody MeSH
- rostliny chemie ultrastruktura MeSH
- zalévání tkání do parafínu metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This chapter gives examples of basic procedures of quantification of plant structures with use of image analysis, which are commonly employed to describe differences among experimental treatments or phenotypes of plant material. Tasks are demonstrated with the use of ImageJ, a widely used public domain Java image processing program. Principles of sampling design based on systematic uniform random sampling for quantitative studies of anatomical parameters are given to obtain their unbiased estimations and simplified "rules of thumb" are presented. The basic procedures mentioned in the text are: (1) sampling, (2) calibration, (3) manual length measurement, (4) leaf surface area measurement, (5) estimation of particle density demonstrated on an example of stomatal density, and (6) analysis of epidermal cell shape.
- MeSH
- epidermis rostlin anatomie a histologie ultrastruktura MeSH
- listy rostlin anatomie a histologie ultrastruktura MeSH
- mikroskopie metody MeSH
- optické zobrazování metody MeSH
- počítačové zpracování obrazu metody MeSH
- průduchy rostlin anatomie a histologie ultrastruktura MeSH
- rostliny anatomie a histologie ultrastruktura MeSH
- software MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Histochemical methods allow for identification and localization of various components within the tissue. Such information on the spatial heterogeneity is not available with biochemical methods. However, there is limitation of the specificity of such detection in context of complex tissue, which is important to consider, and interpretations of the results should regard suitable control treatments if possible. Such methods are valuable extension to specific optical and spectroscopic analytical methods. Here we present a set of selected simple methods of staining and histochemical tests with comments based on our laboratory experience.
- MeSH
- barvení a značení metody MeSH
- barvicí látky analýza MeSH
- buněčná stěna chemie ultrastruktura MeSH
- celulosa analýza MeSH
- histocytochemie metody MeSH
- lignin analýza MeSH
- lipidy analýza MeSH
- mikroskopie metody MeSH
- pektiny analýza MeSH
- rostliny chemie ultrastruktura MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Background and Aim: The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. Methods: In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. Key Results: ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. Conclusions: The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport.
- MeSH
- Arabidopsis genetika metabolismus MeSH
- buněčná stěna metabolismus MeSH
- komplex proteinů 2-3 souvisejících s aktinem genetika metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Seed coats of six pea genotypes contrasting in dormancy were studied by laser desorption/ionization mass spectrometry (LDI-MS). Multivariate statistical analysis discriminated dormant and non-dormant seeds in mature dry state. Separation between dormant and non-dormant types was observed despite important markers of particular dormant genotypes differ from each other. Normalized signals of long-chain hydroxylated fatty acids (HLFA) in dormant JI64 genotype seed coats were significantly higher than in other genotypes. These compounds seem to be important markers likely influencing JI64 seed imbibition and germination. HLFA importance was supported by study of recombinant inbred lines (JI64xJI92) contrasting in dormancy but similar in other seed properties. Furthemore HLFA distribution in seed coat was studied by mass spectrometry imaging. HLFA contents in strophiole and hilum are significantly lower compared to other parts indicating their role in water uptake. Results from LDI-MS experiments are useful in understanding (physical) dormancy (first phases of germination) mechanism and properties related to food processing technologies (e.g., seed treatment by cooking).
Background and Aims: Root absorptive characteristics rely on the presence of apoplastic barriers. However, little is known about the establishment of these barriers within a complex root system, particularly in a major portion of them - the lateral roots. In Zea mays L., the exodermis differentiates under the influence of growth conditions. Therefore, the species presents a suitable model to elucidate the cross-talk among environmental conditions, branching pattern and the maturation of barriers within a complex root system involved in the definition of the plant-soil interface. The study describes the extent to which lateral roots differentiate apoplastic barriers in response to changeable environmental conditions. Methods: The branching, permeability of the outer cell layers and differentiation of the endo- and exodermis were studied in primary roots and various laterals under different types of stress of agronomic importance (salinity, heavy metal toxicity, hypoxia, etc.). Histochemical methods, image analysis and apoplastic tracer assays were utilized. Key Results: The results show that the impact of growth conditions on the differentiation of both the endodermis and exodermis is modulated according to the type/diameter of the root. Fine laterals clearly represent that portion of a complex root system with a less advanced state of barrier differentiation, but with substantial ability to modify exodermis differentiation in response to environmental conditions. In addition, some degree of autonomy in exodermal establishment of Casparian bands (CBs) vs. suberin lamellae (SLs) was observed, as the absence of lignified exodermal CBs did not always fit with the lack of SLs. Conclusions: This study highlights the importance of lateral roots, and provides a first look into the developmental variations of apoplastic barriers within a complex root system. It emphasizes that branching and differentiation of barriers in fine laterals may substantially modulate the root system-rhizosphere interaction.
This chapter gives examples of basic procedures of quantification of plant structures with the use of image analysis, which are commonly employed to describe differences among experimental treatments or phenotypes of plant material. Tasks are demonstrated with the use of ImageJ, a widely used public domain Java image processing program. Principles of sampling design based on systematic uniform random sampling for quantitative studies of anatomical parameters are given to obtain their unbiased estimations and simplified "rules of thumb" are presented. The basic procedures mentioned in the text are (1) sampling, (2) calibration, (3) manual length measurement, (4) leaf surface area measurement, (5) estimation of particle density demonstrated on an example of stomatal density, and (6) analysis of epidermal cell shape.
Histochemical methods allow for identification and localization of various components within the tissue. Such information on the spatial heterogeneity is not available with biochemical methods. However, there is limitation of the specificity of such detection in context of complex tissue, which is important to consider, and interpretations of the results should regard suitable control treatments if possible. Hereby we present set of selected simple staining and histochemical methods with comments based on our laboratory experience.
