endosperm Dotaz Zobrazit nápovědu
Hybridization of closely related plant species is frequently connected to endosperm arrest and seed failure, for reasons that remain to be identified. In this study, we investigated the molecular events accompanying seed failure in hybrids of the closely related species pair Capsella rubella and C. grandiflora. Mapping of QTL for the underlying cause of hybrid incompatibility in Capsella identified three QTL that were close to pericentromeric regions. We investigated whether there are specific changes in heterochromatin associated with interspecific hybridizations and found a strong reduction of chromatin condensation in the endosperm, connected with a strong loss of CHG and CHH methylation and random loss of a single chromosome. Consistent with reduced DNA methylation in the hybrid endosperm, we found a disproportionate deregulation of genes located close to pericentromeric regions, suggesting that reduced DNA methylation allows access of transcription factors to targets located in heterochromatic regions. Since the identified QTL were also associated with pericentromeric regions, we propose that relaxation of heterochromatin in response to interspecies hybridization exposes and activates loci leading to hybrid seed failure.
- MeSH
- Capsella klasifikace genetika MeSH
- centromera genetika MeSH
- chromatin genetika metabolismus MeSH
- chromozomální aberace MeSH
- druhová specificita MeSH
- endosperm genetika MeSH
- heterochromatin genetika metabolismus MeSH
- hybridizace genetická * MeSH
- lokus kvantitativního znaku genetika MeSH
- metylace DNA MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny genetika MeSH
- semena rostlinná genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Understanding the mechanisms regulating the development of cereal seeds is essential for plant breeding and increasing yield. However, the analysis of cereal seeds is challenging owing to the minute size, the liquid character of some tissues, and the tight inter-tissue connections. Here, we demonstrate a detailed protocol for dissection of the embryo, endosperm, and seed maternal tissues at early, middle, and late stages of barley seed development. The protocol is based on a manual tissue dissection using fine-pointed tools and a binocular microscope, followed by ploidy analysis-based purity control. Seed maternal tissues and embryos are diploid, while the endosperm is triploid tissue. This allows the monitoring of sample purity using flow cytometry. Additional measurements revealed the high quality of RNA isolated from such samples and their usability for high-sensitivity analysis. In conclusion, this protocol describes how to practically dissect pure tissues from developing grains of cultivated barley and potentially also other cereals.
Wild barley is abundant, occupying large diversity of sites, ranging from the northern mesic Mediterranean meadows to the southern xeric deserts in Israel. This is also reflected in its wide phenotypic heterogeneity. We investigated the dynamics of DNA content changes in seed tissues in ten wild barley accessions that originated from an environmental gradient in Israel. The flow cytometric measurements were done from the time shortly after pollination up to the dry seeds. We show variation in mitotic cell cycle and endoreduplication dynamics in both diploid seed tissues (represented by seed maternal tissues and embryo) and in the triploid endosperm. We found that wild barley accessions collected at harsher xeric environmental conditions produce higher proportion of endoreduplicated nuclei in endosperm tissues. Also, a comparison of wild and cultivated barley strains revealed a higher endopolyploidy level in the endosperm of wild barley, that is accompanied by temporal changes in the timing of the major developmental phases. In summary, we present a new direction of research focusing on connecting spatiotemporal patterns of endoreduplication in barley seeds and possibly buffering for stress conditions.
- MeSH
- DNA rostlinná genetika MeSH
- endosperm genetika MeSH
- genetická variace genetika MeSH
- ječmen (rod) genetika MeSH
- polyploidie MeSH
- populační genetika metody MeSH
- semena rostlinná genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Izrael MeSH
The main building components of arabinoxylans (AX) are α-L-arabinose and β-D-xylose, but their structure varies largely with cultivar source and tissue. Cereal grains are the best known and most studied source of AX. Traditionally, AX are classified into water-extractable (WE-AX) and non-extractable AX (WN-AX). WN-AX are fixed in the cell wall by non-covalent and covalent bonds with other AX molecules or with other cell wall constituents. In contrast, WE-AX are loosely bonded to the cell wall by crosslinking with other components. A part of the AX from wheat flour, wheat bran can be extracted with water, yielding a WE-AX-containing fraction. Treatment of the water-non-extractable residue with Ba(OH)2 solutions or with an alkaline solution of H2O2 partly solubilizes WN-AX, yielding an alkali-solubilized AX-rich fraction.
- Klíčová slova
- arabinoxylany,
- MeSH
- endosperm chemie MeSH
- polysacharidy * farmakologie chemie izolace a purifikace MeSH
- pšenice chemie MeSH
Anoxia tolerance can be evaluated not only in terms of growth or survival of plant organs during oxygen deprivation, but also in relation to carbohydrate utilization in the context of a well-modulated fermentative metabolism. Rice (Oryza spp.) is unique among cereals, in that it has the distinctive ability to germinate under complete anaerobiosis by using the starchy reserves in its seeds to fuel the anaerobic metabolism. The aim of the present study was to evaluate the ability of germinating rice seedlings to survive a long-term oxygen deficiency [40 days after sowing (DAS)] and the effects on sugar metabolism, focusing on starch degradation as well as soluble sugars transport and storage under anoxia. No significant decline in vitality occurred until 30 DAS though no recovery was detected following longer anoxic treatments. Growth arrest was observed following anoxic treatments longer that 20 DAS, in concomitance with considerably lower ethanol production. Amylolytic activity in embryos and endosperms had similar responses to anoxia, reaching maximum content 30 days after the onset of stress, following which the levels declined for the remainder of the experiment. Under anoxia, average amylolytic activity was twofold higher in embryos than endosperms. Efficient starch degradation was observed in rice under anoxia at the onset of the treatment but it decreased over time and did not lead to a complete depletion. Our analysis of α-amylase activity did not support the hypothesis that starch degradation plays a critical role in explaining differences in vitality and coleoptile growth under prolonged oxygen deprivation.
- MeSH
- alfa-amylasy metabolismus MeSH
- anaerobióza MeSH
- endosperm metabolismus MeSH
- ethanol metabolismus MeSH
- klíčení * MeSH
- kotyledon metabolismus MeSH
- metabolismus sacharidů * MeSH
- rozpustnost MeSH
- rýže (rod) embryologie metabolismus MeSH
- škrob metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
Although reproductive assurance has been suggested to be one of the most important factors shaping the differential distributional patterns between sexuals and asexuals (geographic parthenogenesis), it has only rarely been studied in natural populations of vascular plants with autonomous apomixis. Moreover, there are almost no data concerning the putative relationship between the level of apomictic versus sexual plant reproduction on one hand, and reproductive assurance on the other. We assessed the level of sexual versus apomictic reproduction in diploid and triploid plants of Hieracium alpinum across its distributional range using flow cytometric analyses of seeds, and compared the level of potential and realized seed set, i.e. reproductive assurance, between the two cytotypes under field and greenhouse conditions. Flow cytometric screening of embryos and endosperms of more than 4,100 seeds showed that diploids produced solely diploid progeny sexually, while triploids produced triploid progeny by obligate apomixis. Potential fruit set was much the same in diploids and triploids from the field and the greenhouse experiment. While in the pollination-limited environment in the greenhouse apomictic triploids had considerably higher realized fruit set than sexual diploids, there was no significant difference between cytotypes under natural conditions. In addition, sexuals varied to a significantly larger extent in realized fruit set than asexuals under both natural and greenhouse conditions. Our results indicate that triploid plants reproduce by obligate apomixis, assuring more stable and predictable fruit reproduction when compared to sexual diploids. This advantage could provide apomictic triploids with a superior colonisation ability, mirrored in a strong geographic parthenogenesis pattern observed in this species.
Pectin methylesterase (PME) controls the methylesterification status of pectins and thereby determines the biophysical properties of plant cell walls, which are important for tissue growth and weakening processes. We demonstrate here that tissue-specific and spatiotemporal alterations in cell wall pectin methylesterification occur during the germination of garden cress (Lepidium sativum). These cell wall changes are associated with characteristic expression patterns of PME genes and resultant enzyme activities in the key seed compartments CAP (micropylar endosperm) and RAD (radicle plus lower hypocotyl). Transcriptome and quantitative real-time reverse transcription-polymerase chain reaction analysis as well as PME enzyme activity measurements of separated seed compartments, including CAP and RAD, revealed distinct phases during germination. These were associated with hormonal and compartment-specific regulation of PME group 1, PME group 2, and PME inhibitor transcript expression and total PME activity. The regulatory patterns indicated a role for PME activity in testa rupture (TR). Consistent with a role for cell wall pectin methylesterification in TR, treatment of seeds with PME resulted in enhanced testa permeability and promoted TR. Mathematical modeling of transcript expression changes in germinating garden cress and Arabidopsis (Arabidopsis thaliana) seeds suggested that group 2 PMEs make a major contribution to the overall PME activity rather than acting as PME inhibitors. It is concluded that regulated changes in the degree of pectin methylesterification through CAP- and RAD-specific PME and PME inhibitor expression play a crucial role during Brassicaceae seed germination.
- MeSH
- endosperm enzymologie fyziologie MeSH
- hypokotyl enzymologie fyziologie MeSH
- karboxylesterhydrolasy biosyntéza genetika fyziologie MeSH
- klíčení genetika fyziologie MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- Lepidium sativum enzymologie genetika fyziologie MeSH
- regulace genové exprese u rostlin genetika fyziologie MeSH
- rostlinné proteiny genetika fyziologie MeSH
- semena rostlinná enzymologie fyziologie MeSH
- stanovení celkové genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
Rubus subgen. Rubus includes common European species with highly complicated taxonomy, ongoing hybridisation and facultative apomixis. Out of approximately 750 species recognised in Europe, only 3 diploid sexual species are known, along with numerous apomictic brambles that are highly connected to polyploidy. One exception of a tetraploid taxon is R. ser. Glandulosi, which is known for prevalent sexuality. This taxon highly hybridises with tetraploid members of R. ser. Discolores and leads to the origin of many hybridogenous populations and individuals. In this study, we verify reproduction modes in different diploid, triploid and tetraploid species of subgen. Rubus, with focus on taxa putatively involved in such hybridisation by applying flow cytometric seed screen analysis. We found 100 % sexuality of diploid species, whereas triploid species had obligate unreduced embryo sac development. In contrast, tetraploid plants had varying degrees of sexuality. Additionally, we discovered that R. bifrons has the ability to undergo a reproduction mode switch as a reaction to environmental conditions. These results provide insight into reproductive modes of European brambles and shed light on their reticulate evolution and speciation.
- MeSH
- apomixie MeSH
- délka genomu MeSH
- diploidie MeSH
- druhová specificita MeSH
- endosperm embryologie genetika fyziologie MeSH
- partenogeneze MeSH
- polyploidie * MeSH
- průtoková cytometrie MeSH
- Rosaceae embryologie genetika fyziologie MeSH
- rozmnožování MeSH
- semena rostlinná embryologie genetika fyziologie MeSH
- tetraploidie MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
