14 research outputs found
Comparative study of storage compound breakdown in germinating seeds of three lupine species
Autophagic Machinery of Plant Peroxisomes
Peroxisomes are cell organelles that play an important role in plants in many physiological and developmental processes. The plant peroxisomes harbor enzymes of the β-oxidation of fatty acids and the glyoxylate cycle; photorespiration; detoxification of reactive oxygen and nitrogen species; as well as biosynthesis of hormones and signal molecules. The function of peroxisomes in plant cells changes during plant growth and development. They are transformed from organelles involved in storage lipid breakdown during seed germination and seedling growth into leaf peroxisomes involved in photorespiration in green parts of the plant. Additionally, intensive oxidative metabolism of peroxisomes causes damage to their components. Therefore, unnecessary or damaged peroxisomes are degraded by selective autophagy, called pexophagy. This is an important element of the quality control system of peroxisomes in plant cells. Despite the fact that the mechanism of pexophagy has already been described for yeasts and mammals, the molecular mechanisms by which plant cells recognize peroxisomes that will be degraded via pexophagy still remain unclear. It seems that a plant-specific mechanism exists for the selective degradation of peroxisomes. In this review, we describe the physiological role of pexophagy in plant cells and the current hypotheses concerning the mechanism of plant pexophagy
Transgenic plants as a source of high quality oils
Oleje ro艣linne s膮 niezwykle istotnym, odnawialnym 藕r贸d艂em po偶ywienia cz艂owieka i paszy dla zwierz膮t oraz znajduj膮 wielorakie zastosowania przemys艂owe. Zwi臋kszaj膮ce si臋 zapotrzebowanie ze strony przemys艂u zar贸wno spo偶ywczego jak i niespo偶ywczego na oleje ro艣linne i ich sk艂adniki wymusza poszukiwania nowych, efektywniejszych i ekonomiczniejszych 藕r贸de艂 ich pozyskiwania. Wsp贸艂cze艣nie nie wystarczy tylko zwi臋kszenie area艂u upraw ro艣lin oleistych, ale konieczne s膮 te偶 inne przedsi臋wzi臋cia prowadz膮ce do uzyskania nowych odmian. Odmian zar贸wno akumuluj膮cych wi臋cej oleju ale te偶 odmian, kt贸re zdolne s膮 do biosyntezy zwi膮zk贸w naturalnie w nich niewyst臋puj膮cych b膮d藕 wyst臋puj膮cych w 艣ladowych ilo艣ciach. W tego typu badaniach si臋ga si臋 po dobrze znane, powszechnie uprawiane ro艣liny u偶ytkowe takie jak rzepak czy soja. Jednak w zdecydowanej wi臋kszo艣ci, prace nad nowymi odmianami ro艣lin transgenicznych zaczynaj膮 si臋 od bada艅 prowadzonych na ro艣linie modelowej, jak膮 jest Arabidopsis thaliana. W niniejszym opracowaniu przedstawiono szereg przyk艂ad贸w ro艣lin modyfikowanych genetycznie, w kt贸rych uzyskano wzrost zawarto艣ci akumulowanego oleju, zmodyfikowano sk艂ad oleju pod k膮tem diety cz艂owieka jak r贸wnie偶 wymuszono syntez臋 wielu zwi膮zk贸w warto艣ciowych dla przemys艂u. Przytoczono r贸wnie偶 liczne przyk艂ady zastosowa艅 przemys艂owych dla olej贸w ro艣linnych i ich sk艂adnik贸w. Jednym z cel贸w tego opracowania jest pokazanie wielokierunkowo艣ci bada艅 maj膮cych doprowadzi膰 do uzyskania nowych genetycznie modyfikowanych odmian cechuj膮cych si臋 zmienionym metabolizmem t艂uszczowym.Vegetable oils represent a very important, renewable source of human food, animal feed and have multiple industrial applications. Increasing demand from both food and non-food industry for vegetable oils and their components forces the search for new, more efficient and more economical sources of their acquisition. Today, it is not enough just to increase the acreage of oil plants; there is a need for projects leading to the creation of new varieties. The new varieties should either accumulate more oil or can be capable of biosynthesis of compounds that naturally do not occur in their tissues or are present in trace amounts. In this kind of research well-known commonly used crops such as oilseed rape and soybean are included. However, the vast majority of works on new varieties of transgenic plants start from research conducted on the model plant Arabidopsis thaliana. This paper presents several examples of genetically modified plants with increased oil level, modified oil composition regarding human diet, and with constrained synthesis of many compounds valuable to the industry. Numerous examples of industrial applications for vegetable oils and their components are presented. One of the aims of this paper is demonstration that plurality of research lead to new genetically modified varieties with modified lipid metabolism
Vacuolar Processing Enzymes in Plant Programmed Cell Death and Autophagy
Vacuolar processing enzymes (VPEs) are plant cysteine proteases that are subjected to autoactivation in an acidic pH. It is presumed that VPEs, by activating other vacuolar hydrolases, are in control of tonoplast rupture during programmed cell death (PCD). Involvement of VPEs has been indicated in various types of plant PCD related to development, senescence, and environmental stress responses. Another pathway induced during such processes is autophagy, which leads to the degradation of cellular components and metabolite salvage, and it is presumed that VPEs may be involved in the degradation of autophagic bodies during plant autophagy. As both PCD and autophagy occur under similar conditions, research on the relationship between them is needed, and VPEs, as key vacuolar proteases, seem to be an important factor to consider. They may even constitute a potential point of crosstalk between cell death and autophagy in plant cells. This review describes new insights into the role of VPEs in plant PCD, with an emphasis on evidence and hypotheses on the interconnections between autophagy and cell death, and indicates several new research opportunities
Completing Autophagy: Formation and Degradation of the Autophagic Body and Metabolite Salvage in Plants
Autophagy is an evolutionarily conserved process that occurs in yeast, plants, and animals. Despite many years of research, some aspects of autophagy are still not fully explained. This mostly concerns the final stages of autophagy, which have not received as much interest from the scientific community as the initial stages of this process. The final stages of autophagy that we take into consideration in this review include the formation and degradation of the autophagic bodies as well as the efflux of metabolites from the vacuole to the cytoplasm. The autophagic bodies are formed through the fusion of an autophagosome and vacuole during macroautophagy and by vacuolar membrane invagination or protrusion during microautophagy. Then they are rapidly degraded by vacuolar lytic enzymes, and products of the degradation are reused. In this paper, we summarize the available information on the trafficking of the autophagosome towards the vacuole, the fusion of the autophagosome with the vacuole, the formation and decomposition of autophagic bodies inside the vacuole, and the efflux of metabolites to the cytoplasm. Special attention is given to the formation and degradation of autophagic bodies and metabolite salvage in plant cells
New Insight into Plant Signaling: Extracellular ATP and Uncommon Nucleotides
New players in plant signaling are described in detail in this review: extracellular ATP (eATP) and uncommon nucleotides such as dinucleoside polyphosphates (NpnN’s), adenosine 5′-phosphoramidate (NH2-pA), and extracellular NAD+ and NADP+ (eNAD(P)+). Recent molecular, physiological, and biochemical evidence implicating concurrently the signaling role of eATP, NpnN’s, and NH2-pA in plant biology and the mechanistic events in which they are involved are discussed. Numerous studies have shown that they are often universal signaling messengers, which trigger a signaling cascade in similar reactions and processes among different kingdoms. We also present here, not described elsewhere, a working model of the NpnN’ and NH2-pA signaling network in a plant cell where these nucleotides trigger induction of the phenylpropanoid and the isochorismic acid pathways yielding metabolites protecting the plant against various types of stresses. Through these signals, the plant responds to environmental stimuli by intensifying the production of various compounds, such as anthocyanins, lignin, stilbenes, and salicylic acid. Still, more research needs to be performed to identify signaling networks that involve uncommon nucleotides, followed by omic experiments to define network elements and processes that are controlled by these signals
Sugar Starvation Disrupts Lipid Breakdown by Inducing Autophagy in Embryonic Axes of Lupin (Lupinus spp.) Germinating Seeds
Under nutrient deficiency or starvation conditions, the mobilization of storage compounds during seed germination is enhanced to primarily supply respiratory substrates and hence increase the potential of cell survival. Nevertheless, we found that, under sugar starvation conditions in isolated embryonic axes of white lupin (Lupinus albus L.) and Andean lupin (Lupinus mutabilis Sweet) cultured in vitro for 96 h, the disruption of lipid breakdown occurs, as was reflected in the higher lipid content in the sugar-starved (-S) than in the sucrose-fed (+S) axes. We postulate that pexophagy (autophagic degradation of the peroxisome鈥攁 key organelle in lipid catabolism) is one of the reasons for the disruption in lipid breakdown under starvation conditions. Evidence of pexophagy can be: (i) the higher transcript level of genes encoding proteins of pexophagy machinery, and (ii) the lower content of the peroxisome marker Pex14p and its increase caused by an autophagy inhibitor (concanamycin A) in -S axes in comparison to the +S axes. Additionally, based on ultrastructure observation, we documented that, under sugar starvation conditions lipophagy (autophagic degradation of whole lipid droplets) may also occur but this type of selective autophagy seems to be restricted under starvation conditions. Our results also show that autophagy occurs at the very early stages of plant growth and development, including the cells of embryonic seed organs, and allows cell survival under starvation conditions