Abstract
Proper orchestration of the thousands of biochemical processes that are essential to the life of every cell requires highly organized cellular compartmentalization of dedicated ...microenvironments. There are 2 ways to create this intracellular segregation to optimize cellular function. One way is to create specific organelles, enclosed spaces bounded by lipid membranes that regulate macromolecular flux in and out of the compartment. A second way is via membraneless biomolecular condensates that form due to to liquid-liquid phase separation. Although research on these membraneless condensates has historically been performed using animal and fungal systems, recent studies have explored basic principles governing the assembly, properties, and functions of membraneless compartments in plants. In this review, we discuss how phase separation is involved in a variety of key processes occurring in Cajal bodies (CBs), a type of biomolecular condensate found in nuclei. These processes include RNA metabolism, formation of ribonucleoproteins involved in transcription, RNA splicing, ribosome biogenesis, and telomere maintenance. Besides these primary roles of CBs, we discuss unique plant-specific functions of CBs in RNA-based regulatory pathways such as nonsense-mediated mRNA decay, mRNA retention, and RNA silencing. Finally, we summarize recent progress and discuss the functions of CBs in responses to pathogen attacks and abiotic stresses, responses that may be regulated via mechanisms governed by polyADP-ribosylation. Thus, plant CBs are emerging as highly complex and multifunctional biomolecular condensates that are involved in a surprisingly diverse range of molecular mechanisms that we are just beginning to appreciate.
Biomolecular condensates in plants perform many more functions than were previously known; the roles of Cajal bodies, are explored in depth, shedding light on the numerous functions performed by biomolecular condensates in plants.
Abstract Due to the nanoscale size and the strictly controlled and consistent morphologies of viruses, there has been a recent interest in utilizing them in nanotechnology. The structure, surface ...chemistries and physical properties of many viruses have been well elucidated, which have allowed identification of regions of their capsids which can be modified either chemically or genetically for nanotechnological uses. In this review we focus on the use of such modifications for the functionalization and production of viruses and empty viral capsids that can be readily decorated with metals in a highly tuned manner. In particular, we discuss the use of two plant viruses (Cowpea mosaic virus and Tobacco mosaic virus) which have been extensively used for production of novel metal nanoparticles (<100 nm), composites and building blocks for 2D and 3D materials, and illustrate their applications.
Nanocarriers are widely used for efficient delivery of different cargo into mammalian cells; however, delivery into plant cells remains a challenging issue due to physical and mechanical barriers ...such as the cuticle and cell wall. Here, we discuss recent progress on biodegradable and biosafe nanomaterials that were demonstrated to be applicable to the delivery of nucleic acids into plant cells. This review covers studies the object of which is the plant cell and the cargo for the nanocarrier is either DNA or RNA. The following nanoplatforms that could be potentially used for nucleic acid foliar delivery via spraying are discussed: mesoporous silica nanoparticles, layered double hydroxides (nanoclay), carbon-based materials (carbon dots and single-walled nanotubes), chitosan and, finally, cell-penetrating peptides (CPPs). Hybrid nanomaterials, for example, chitosan- or CPP-functionalized carbon nanotubes, are taken into account. The selected nanocarriers are analyzed according to the following aspects: biosafety, adjustability for the particular cargo and task (e.g., organelle targeting), penetration efficiency and ability to protect nucleic acid from environmental and cellular factors (pH, UV, nucleases, etc.) and to mediate the gradual and timely release of cargo. In addition, we discuss the method of application, experimental system and approaches that are used to assess the efficiency of the tested formulation in the overviewed studies. This review presents recent progress in developing the most promising nanoparticle-based materials that are applicable to both laboratory experiments and field applications.
Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated genes (Cas) is a prokaryotic adaptive immune system which has been reprogrammed into a precise, simple, and ...efficient gene targeting technology. This emerging technology is revolutionizing various areas of life sciences, medicine, and biotechnology and has raised significant interest among plant biologists, both in basic science and in plant protection and breeding. In this review, we describe the basic principles of CRISPR/Cas systems, and how they can be deployed to model plants and crops for the control, monitoring, and study of the mechanistic aspects of plant virus infections. We discuss how Cas endonucleases can be used to engineer plant virus resistance by directly targeting viral DNA or RNA, as well as how they can inactivate host susceptibility genes. Additionally, other applications of CRISPR/Cas in plant virology such as virus diagnostics and imaging are reviewed. The review also provides a systemic comparison between CRISPR/Cas technology and RNA interference approaches, the latter of which has also been used for development of virus-resistant plants. Finally, we outline challenges to be solved before CRISPR/Cas can produce virus-resistant crop plants which can be marketed.
We report the synthesis and characterization of amorphous iron oxide nanoparticles from iron salts in aqueous extracts of monocotyledonous (Hordeum vulgare) and dicotyledonous (Rumex acetosa) plants. ...The nanoparticles were characterized by TEM, absorbance spectroscopy, SAED, EELS, XPS, and DLS methods and were shown to contain mainly iron oxide and iron oxohydroxide. H. vulgare extracts produced amorphous iron oxide nanoparticles with diameters of up to 30 nm. These iron nanoparticles are intrinsically unstable and prone to aggregation; however, we rendered them stable in the long term by addition of 40 mM citrate buffer pH 3.0. In contrast, amorphous iron oxide nanoparticles (diameters of 10–40 nm) produced using R. acetosa extracts are highly stable. The total protein content and antioxidant capacity are similar for both extracts, but pH values differ (H. vulgare pH 5.8 vs R. acetosa pH 3.7). We suggest that the presence of organic acids (such oxalic or citric acids) plays an important role in the stabilization of iron nanoparticles, and that plants containing such constituents may be more efficacious for the green synthesis of iron nanoparticles.
Peptide hormones are implicated in many important aspects of plant life and are usually synthesized as precursor proteins. In contrast to animals, data for plant peptide hormone maturation are scarce ...and the specificity of processing enzyme(s) is largely unknown. Here we tested a hypothesis that processing of prosystemin, a precursor of tomato (Solanum lycopersicum) wound hormone systemin, is performed by phytaspases, aspartate-specific proteases of the subtilase family.
Following the purification of phytaspase from tomato leaves, two tomato phytaspase genes were identified, the cDNAs were cloned and the recombinant enzymes were obtained after transient expression in Nicotiana benthamiana.
The newly identified tomato phytaspases hydrolyzed prosystemin at two aspartate residues flanking the systemin sequence. Site-directed mutagenesis of the phytaspase cleavage sites in prosystemin abrogated not only the phytaspase-mediated processing of the prohormone in vitro, but also the ability of prosystemin to trigger the systemic wound response in vivo.
The data show that the prohormoneprosystemin requires processing for signal biogenesis and biological activity. The identification of phytaspases as the proteases involved in prosystemin maturation provides insight into the mechanisms of wound signaling in tomato. Our data also suggest a novel role for cell death-related proteases in mediating defense signaling in plants.
Potato virus Y, an important viral pathogen of potato, has several genetic variants and geographic distributions which could be affected by environmental factors, aphid vectors, and reservoir plants. ...PVY is transmitted to virus-free potato plants by aphids and passed on to the next vegetative generations through tubers, but the effects of tuber transmission in PVY is largely unknown. By using high-throughput sequencing, we investigated PVY populations transmitted to potato plants by aphids in different climate zones of Russia, namely the Moscow and Astrakhan regions. We analyzed sprouts from the tubers produced by field-infected plants to investigate the impact of tuber transmission on PVY genetics. We found a significantly higher diversity of PVY isolates in the Astrakhan region, where winters are shorter and milder and summers are warmer compared to the Moscow region. While five PVY types, NTNa, NTNb, N:O, N-Wi, and SYR-I, were present in both regions, SYRI-II, SYRI-III, and 261-4 were only found in the Astrakhan region. All these recombinants were composed of the genome sections derived from PVY types O and N, but no full-length sequences of such types were present. The composition of the PVY variants in the tuber sprouts was not always the same as in their parental plants, suggesting that tuber transmission impacts PVY genetics.
The external application of double-stranded RNA (dsRNA) has recently been developed as a non-transgenic approach for crop protection against pests and pathogens. This novel and emerging approach has ...come to prominence due to its safety and environmental benefits. It is generally assumed that the mechanism of dsRNA-mediated antivirus RNA silencing is similar to that of natural RNA interference (RNAi)-based defence against RNA-containing viruses. There is, however, no direct evidence to support this idea. Here, we provide data on the high-throughput sequencing (HTS) analysis of small non-coding RNAs (sRNA) as hallmarks of RNAi induced by infection with the RNA-containing potato virus Y (PVY) and also by exogenous application of dsRNA which corresponds to a fragment of the PVY genome. Intriguingly, in contrast to PVY-induced production of discrete 21 and 22 nt sRNA species, the externally administered PVY dsRNA fragment led to generation of a non-canonical pool of sRNAs, which were present as ladders of ~18–30 nt in length; suggestive of an unexpected sRNA biogenesis pathway. Interestingly, these non-canonical sRNAs are unable to move systemically and also do not induce transitive amplification. These findings may have significant implications for further developments in dsRNA-mediated crop protection.
The nucleolus is the most conspicuous domain in the eukaryotic cell nucleus, whose main function is ribosomal RNA (rRNA) synthesis and ribosome biogenesis. However, there is growing evidence that the ...nucleolus is also implicated in many other aspects of cell biology, such as regulation of cell cycle, growth and development, senescence, telomerase activity, gene silencing, responses to biotic and abiotic stresses. In the first part of the review, we briefly assess the traditional roles of the plant nucleolus in rRNA synthesis and ribosome biogenesis as well as possible functions in other RNA regulatory pathways such as splicing, nonsense-mediated mRNA decay and RNA silencing. In the second part of the review we summarize recent progress and discuss already known and new hypothetical roles of the nucleolus in plant growth and development. In addition, this part will highlight studies showing new nucleolar functions involved in responses to pathogen attack and abiotic stress. Cross-talk between the nucleolus and Cajal bodies is also discussed in the context of their association with poly(ADP ribose)polymerase (PARP), which is known to play a crucial role in various physiological processes including growth, development and responses to biotic and abiotic stresses.
Nanocarriers provide a number of undeniable advantages that could improve the bioavailability of active agents for human, animal, and plant cells. In this study, we compared hybrid nanoparticles ...(HNPs) consisting of a calcium phosphate core coated with chitosan with unmixed calcium phosphate (CaP) and chitosan nanoparticles (CSNPs) as carriers of a model substrate, enalaprilat. This tripeptide analog is an inhibitor of angiotensin-converting enzyme and was chosen by its ability to lower intraocular pressure (IOP). In particular, we evaluated the physicochemical characteristics of the particles using dynamic light scattering (DLS) and scanning electron microscopy (SEM) and analyzed their ability to incorporate and release enalaprilat. HNPs exhibited the highest drug loading capacity and both HNPs and CSNPs demonstrated slow drug release. The comparison of the physiological effects of enalaprilat-loaded CaP particles, HNPs, and CSNPs in terms of their impact on IOP in rabbits revealed a clear advantage of hybrid nanoparticles over both inorganic and chitosan nanoparticles. These results could have important mechanistic implications for developing nano-based delivery systems for other medical, veterinary, and agricultural applications.
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