Cell cycle control by the target of rapamycin signalling pathway in plants

Cells need to ensure a sufficient nutrient and energy supply before committing to proliferate. In response to positive mitogenic signals, such as light, sugar availability, and hormones, the target of rapamycin (TOR) signalling pathway promotes cell growth that connects to the entry and passage through the cell division cycle via multiple signalling mechanisms. Here, we summarize current understanding of cell cycle regulation by the RBR-E2F regulatory hub and the DREAM-like complexes, and highlight possible functional relationships between these regulators and TOR signalling. A genetic screen recently uncovered a downstream signalling component to TOR that regulates cell proliferation, YAK1, a member of the dual specificity tyrosine phosphorylation-regulated kinase (DYRK) family. YAK1 activates the plant-specific SIAMESE-RELATED (SMR) cyclin-dependent kinase inhibitors and therefore could be important to regulate both the CDKA-RBR-E2F pathway to control the G1/S transition and the mitotic CDKB1;1 to control the G2/M transition. TOR, as a master regulator of both protein synthesis-driven cell growth and cell proliferation is also central for cell size homeostasis. We conclude the review by briefly highlighting the potential applications of combining TOR and cell cycle knowledge in the context of ensuring future food security

A gabonavertikum komplex beruházás-elemzés módszertani fejlesztése = Methodological development of investment analysis in corn industry

A kutatás során a gabonavertikum komplex beruházás-elemzés módszertani fejlesztését a pályázatban megfogalmazott célokat szem előtt tartva végeztük el. A kutatás eredménye az alábbiakban összegezhető: - A kutatás során áttekintettük a beruházás-elemzésben alkalmazott módszereket, a dinamikus és statikus mutatókat egyaránt. Megállapítottuk, hogy megalapozottabbá tehető a döntéshozatal, az időtényező figyelembe vételével, ezért a további vizsgálatoknál a dinamikus mutatókkal számoltunk. - A dinamikus mutatókra épített elemzések során a beruházás kockázata elemezhető érzékenységvizsgálattal, illetve a sztochasztikus tényezőket valószínűségi változóknak tekintve szimulációs módszerekkel. Ezek alapján a kutatás során a dinamikus mutatókra épülő beruházási modelleket továbbfejlesztettük, és a szimuláció alkalmazásával lehetővé tettük a modellekben a kockázat megjelenítését. - Esettanulmányok készítésével teszteltük a kifejlesztett modellek gyakorlati alkalmazhatóságát. A kutatás értékét növeli, hogy a tesztelések után a kifejlesztett modelleket tényleges gabonaipari beruházások döntés-előkészítésben sikeresen alkalmazták. | In the course of research we did the methodical development of cereal sector's investment analysis bearing in mind the objectives set out in the project. The result of the project can be summarized as follows: - In the research we reviewed the methods used for investment analysis, both dynamic and statistical indices. We found out that decision-making can be made more established by considering time factor, therefore in further studies we calculated with dynamic indices. - In the analyses with dynamic indices, the risk of the investment can be analyzed by sensitivity analysis and also by simulation methods if we consider stochastic factors as probability variable. On that basis, in the research we developed the investment models based on dynamic indices and by adapting simulation we made possible to present risk in the models. - We tested the developed models'adaptability in practice by doing case studies. The value of the research is enhanced by the fact that the developed models after testing were adapted successfully in the decision preparations of investments in cereals sector

Növénytermesztési döntéstámogatás és kockázatelemzés módszertani fejlesztése = Development of methodology of crop decision support and hazard analysis

A kutatás során a pályázati célokat szem előtt tartva a növénytermesztési döntéstámogatás és kockázatelemzés módszertani fejlesztését végeztük el. A kutatás eredménye az alábbiakban összegezhető: - Áttekintettük a jelenleg alkalmazott döntéstámogatási rendszereket és kockázatelemzési módszereket, elemeztük termelési kockázatot európai és regionális szinten. - Kifejlesztettük az NTER elnevezésű MS Accesre és MS Excelre alapozott növénytermesztési tervező-elemző rendszert. Az adattörzsek kezelését, ágazati technológiák készítését, valamint az ágazati gazdasági értékeléseket MS Acces segítségével, míg a vetésszerkezeti és kockázati modellezést MS Excellel végezzük. - Ezt követően az NTER-re alapozva vetésszerkezeti variánsok összehasonlító elemzését végeztük el a Hajdúságban. - Debreceni nemesítésű és standard búzafajták termőképesség és termésbiztonság elemzését végeztük el különböző termőhelyi adottságok figyelembevételével. Az elemzést átlag-szórás kritériumok, illetve MOTAD modell felhasználásával végeztük. | In our research we have done the methodological development of decision support and risk analysis for crop enterprises having competition purposes in sight. The result of the research can be summarized as follows: - We looked over the currently applied systems and methods used for risk analysis. We analyzed production risk on European and regional levels. - We have developed a planning-analyzing system for crop enterprises called NTER, based on MS Acces and MS Excel. We did the management of data, creation of enterprise technologies, and economic analyzes of the enterprises by using MS Acces, while modeling crop structure and risk we did by MS Excel. - After this on the basis of the NTER we made the crop structure variants' comparative analyses in the region of Hajdúság. - We did productivity and yield reliability analyses for standard and grafted in Debrecen wheat species taking into consideration the production site's features. We did the analysis by applying average-variance criteria and MOTAD model

How Different Mulch Materials Regulate Soil Moisture and Microbiological Activity?

As a result of climate change, the frequency of droughts across Europe is showing an increasing trend. The solution to this problem can be various soil cover techniques, which help to preserve soil moisture and soil biological activity, thereby increasing crop yield. In our research, we examined how different mulch materials affect the regulation of soil moisture and the microbiological activity of the soil. The experiments were set up on two sites: a sandy soil with a low soil organic matter content (Királyhalom, Serbia) and an coarse loamy soil with a higher water capacity (Thessaloniki, Greece). The treatments were set up in 4 repetitions with pepper plants (Capsicum annuum L.). Daily intensive irrigation with wool mulch, agrotextile, straw mulch and control treatments was used on the Serbian site. The irrigation was carried out every 6 days at the Greek site, where the treatments were as follows: wool mulch with plants, wool mulch without plants, plants without mulch and the control without plants. The yield was measured, and the moisture content, β-glucosidase activity and active (permanganate oxidizable) carbon content of the soils at the time of sampling were examined every 2 weeks. In the Serbian area, wool mulch showed significantly lower β-glucosidase activity compared to the other treatments. This was presumably due to the good water absorption capacity of the wool mulch and the fact that the soil could not aerate in addition to the intensive irrigation, thus the enzyme activity decreased. All mulch treatments increased the active carbon content compared to the untreated control, with the straw mulch to the greatest extent. In the extensively irrigated Greek soil, β-glucosidase was significantly higher in pepper plots covered with wool mulch compared to the control area without plants, but also higher compared to pepper plots not covered with wool mulch. The higher yield results measured on the mulched plots indicate that, in addition to water retention, biological activity also plays a major role in the development of yields. The effect of each mulching method on soil biological activity depends on the degradability of the mulch material, the frequency of irrigation, and the soil's water-holding capacity

The Arabidopsis Zinc Finger Protein 3 interferes with ABA and light signaling in seed germination and plant development

Seed germination is controlled by environmental signals, including light and endogenous phytohormones. Abscisic acid (ABA) inhibits, whereas gibberellin promotes, germination and early seedling development, respectively. Here, we report that ZFP3, a nuclear C2H2 zinc finger protein, acts as a negative regulator of ABA suppression of seed germination in Arabidopsis (Arabidopsis thaliana). Accordingly, regulated overexpression of ZFP3 and the closely related ZFP1, ZFP4, ZFP6, and ZFP7 zinc finger factors confers ABA insensitivity to seed germination, while the zfp3 zfp4 double mutant displays enhanced ABA susceptibility. Reduced expression of several ABA-induced genes, such as RESPONSIVE TO ABSCISIC ACID18 and transcription factor ABSCISIC ACID-INSENSITIVE4 (ABI4), in ZFP3 overexpression seedlings suggests that ZFP3 negatively regulates ABA signaling. Analysis of ZFP3 overexpression plants revealed multiple phenotypic alterations, such as semidwarf growth habit, defects in fertility, and enhanced sensitivity of hypocotyl elongation to red but not to far-red or blue light. Analysis of genetic interactions with phytochrome and abi mutants indicates that ZFP3 enhances red light signaling by photoreceptors other than phytochrome A and additively increases ABA insensitivity conferred by the abi2, abi4, and abi5 mutations. These data support the conclusion that ZFP3 and the related ZFP subfamily of zinc finger factors regulate light and ABA responses during germination and early seedling development

The role of Arabidopsis glutathione transferase F9 gene under oxidative stress in seedlings

Arabidopsis thaliana contains 54 soluble glutathione transferases (GSTs, EC 2.5.1.18), which are thought to play major roles in oxidative stress responses, but little is known about the function of individual isoenzymes. The role of AtGST phi 9 (GSTF9) in the salt- and salicylic acid response was investigated using 2-week-old Atgstf9 and wild type (Wt) plants. Atgstf9 mutants accumulated more ascorbic acid (AsA) and glutathione (GSH) and had decreased glutathione peroxidase (GPOX) activity under control conditions. Treatment of 2-week-old seedlings with 10−7 M salicylic acid (SA) for 48 h resulted in elevated H2O2 level and enhanced GST activity in Atgstf9 plants, 10−5 M SA treatment enhanced the malondialdehyde and dehydroascorbate contents compared to Wt. 50 and 150 mM NaCl increased the GST activity, AsA and GSH accumulation in Atgstf9 seedlings more pronounced than in Wt plants. We found that the Atgstf9 mutants had altered redox homeostasis under control and stress conditions, in which elevated AsA and GSH levels and modified GST and GPOX activities may play significant role. The half-cell potential values calculated from the concentration of GSH and GSSG indicate that this GST isoenzyme has an important role in the salt stress response

The Heat Shock Factor A4A confers salt tolerance and is regulated by oxidative stress and the Mitogen-Activated Protein kinases, MPK3 and MPK6

Heat-shock factors (HSFs) are principal regulators of plant responses to several abiotic stresses. Here we show that estradiol-dependent induction of HSFA4A confers enhanced tolerance to salt and oxidative agents, whereas inactivation of HSFA4A results in hypersensitivity to salt stress in Arabidopsis. Estradiol-induction of HSFA4A in transgenic plants decreases, while the knockout hsfa4a mutation elevates hydrogen peroxide accumulation and lipid peroxidation. Overexpression of HSFA4A alters the transcription of a large set of genes regulated by oxidative stress. In yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays HSFA4A shows homomeric interaction which is reduced by alanine replacement of three conserved cysteine residues. HSFA4A interacts with mitogen-activated protein kinases MPK3 and MPK6 in yeast and plant cells. MPK3 and MPK6 phosphorylate HSFA4A in vitro on three distinct sites, Ser309 being the major phosphorylation site. Activation of the MPK3 and MPK6 MAPK pathway led to the transcriptional activation of the heat-shock protein gene HSP17.6A. In agreement that mutation of Ser309 to alanine strongly diminished phosphorylation of HSFA4A, it also strongly reduced the transcriptional activation of HSP17.6A. These data suggest that HSFA4A is a substrate of the MPK3/6 signalling and it regulates stress responses in Arabidopsis

E2FA and E2FB transcription factors coordinate cell proliferation with seed maturation

The E2F transcription factors and the RETINOBLASTOMA RELATED (RBR) repressor protein are principal regulators coordinating cell proliferation with differentiation, but their role during seed development is little understood. We show that in the fully developed embryos, cell number was not affected either in single or double mutants for the activator-type E2FA and E2FB Accordingly, these E2Fs are only partially required for the expression of cell cycle genes. In contrast, the expression of key seed maturation genes; LEAFY COTYLEDON 1-2 (LEC1-2), ABSCISIC ACID INSENSITIVE 3 (ABI3), FUSCA 3 (FUS3) and WRINKLED 1 (WRI1) are upregulated in the e2fab double mutant embryo. In accordance, E2FA directly regulates LEC2, and mutation at the consensus E2F-binding site in LEC2 promoter de-represses its activity during the proliferative stage of seed development. Additionally, the major seed storage reserve proteins, 12S globulin and 2S albumin became prematurely accumulated at the proliferating phase of seed development in the e2fab double mutant. Our findings reveal a repressor function of the activator E2Fs to restrict the seed maturation program until the cell proliferation phase is completed