Proline affects the size of the root meristematic zone in Arabidopsis

We reported previously that root elongation in Arabidopsis is promoted by exogenous proline, raising the possibility that this amino acid may modulate root growth. To evaluate this hypothesis we used a combination of genetic, pharmacological and molecular analyses, and showed that proline specifically affects root growth by modulating the size of the root meristem. The effects of proline on meristem size are parallel to, and independent from, hormonal pathways, and do not involve the expression of genes controlling cell differentiation at the transition zone. On the contrary, proline appears to control cell division in early stages of postembryonic root development, as shown by the expression of the G2/M-specific CYCLINB1;1 (CYCB1;1) gene. The overall data suggest that proline can modulate the size of root meristematic zone in Arabidopsis likely controlling cell division and, in turn, the ratio between cell division and cell differentiation

Proline synthesis in developing microspores is required for pollen development and fertility

Background: In many plants, the amino acid proline is strongly accumulated in pollen and disruption of proline synthesis caused abortion of microspore development in Arabidopsis. So far, it was unclear whether local biosynthesis or transport of proline determines the success of fertile pollen development. Results: We analyzed the expression pattern of the proline biosynthetic genes PYRROLINE-5-CARBOXYLATE SYNTHETASE 1 & 2 (P5CS1 & 2) in Arabidopsis anthers and both isoforms were strongly expressed in developing microspores and pollen grains but only inconsistently in surrounding sporophytic tissues. We introduced in a p5cs1/p5cs1 p5cs2/P5CS2 mutant background an additional copy of P5CS2 under the control of the Cauliflower Mosaic Virus (CaMV) 35S promoter, the tapetum-specific LIPID TRANSFER PROTEIN 12 (Ltp12) promoter or the pollen-specific At5g17340 promoter to determine in which site proline biosynthesis can restore the fertility of proline-deficient microspores. The specificity of these promoters was confirmed by β-glucuronidase (GUS) analysis, and by direct proline measurement in pollen grains and stage-9/10 anthers. Expression of P5CS2 under control of the At5g17340 promoter fully rescued proline content and normal morphology and fertility of mutant pollen. In contrast, expression of P5CS2 driven by either the Ltp12 or CaMV35S promoter caused only partial restoration of pollen development with little effect on pollen fertility. Conclusions: Overall, our results indicate that proline transport is not able to fulfill the demand of the cells of the male germ line. Pollen development and fertility depend on local proline biosynthesis during late stages of microspore development and in mature pollen grains

Environmental Control of Rice Flowering Time

Correct measurement of environmental parameters is fundamental for plant fitness and survival, as well as for timing developmental transitions, including the switch from vegetative to reproductive growth. Important parameters affecting flowering time include day length (photoperiod) and temperature. Their response pathways have been best described in Arabidopsis, that currently offers a detailed conceptual framework and serves as term of comparison also for other species. Rice, the focus of this review, also possesses a photoperiodic flowering pathway, but 150M years of divergent evolution in very different environments have diversified its molecular architecture. The ambient temperature perception pathway is strongly intertwined with the photoperiod pathway and essentially converges on the same genes to modify flowering time. When observing network topologies it is evident that the rice flowering network is centered on EARLY HEADING DATE 1, a rice-specific transcriptional regulator. Here, we summarize the most important features of the rice photoperiodic flowering network, with an emphasis on its uniqueness, and discuss its connections with hormonal, temperature perception and stress pathways

Proline Affects Root Meristem Size In Arabidopsis thaliana

La crescita della radice in Arabidopsis thaliana si basa sull'attività della zona meristematica. La dimensione del meristema della radice è regolato dai fitoormoni auxina, citochinine e gibberelline, che controllano un circuito di espressione genica che converge sul gene SHY2. Regolando SHY2, gli ormoni vegetali controllano il rapporto tra la divisione cellulare e il differnziamento cellulare. In un lavoro precedente abbiamo riportato che l'allungamento della radice di Arabidopsis è promosso da concentrazioni micromolari di prolina esogena. Al fine di verificare se un mutante con deficit di prolina è caratterizzato da un problema nella crescita delle radici, abbiamo analizzato la lunghezza, rispetto al wild type , delle radici nel mutante p5cs1 p5cs2 / P5CS2. Le nostre analisi mostrano che piante con genotipo p5cs1 p5cs2 / P5CS2 sono caratterizzate da radici più brevi, e meristemi più piccole rispetto al wild type. Questi dati preliminari suggeriscono che la prolina in grado di modulare le dimensioni del meristema radicale e, a sua volta, la crescita delle radici. Per valutare questa ipotesi abbiamo usato una combinazione di analisi genetiche, farmacologiche e molecolari, e dimostrato che prolina colpisce specificamente crescita delle radici modulandone la dimensione del meristema . Gli effetti della prolina sulla dimensione del meristema sono paralleli e indipendenti dalle vie ormonali, e non comportano l'espressione di geni che controllano il differenziamento cellulare in corrispondenza della zona di transizione (SHY2). Al contrario, la prolina sembra controllare la divisione cellulare nelle prime fasi postembrionali di sviluppo delle radici, come indicato dall'espressione del gene CYCLINB1 che conrolla la transizione tra le fasi G2 / M. I dati complessivi indicano che la prolina può modulare la dimensione della zona meristematica della radice, probabilmente controllando la divisione cellulare.The Arabidopsis thaliana root growt relies on the activity of the root meristematic zone . The size of root meristem is regulated by the plant hormones auxin, cytokinin and gibberellin, which control a short regulatory circuit converging on the gene SHY2. By regulating SHY2, plant hormones control the ratio between cell division and cell differentiation. In a previus work we reported that root elongation in Arabidopsis is promoted by micromolar concentrations of exogenous proline. In order to verify whether a proline-deficient mutant is hampered in root growth, we analyzed the length, relative to wild type, of roots from the proline-deficient mutant p5cs1 p5cs2/P5CS2. Our analyses display that the p5cs1 p5cs2/P5CS2 mutant is characterized by shorter roots, and smaller meristems than wild type. These preliminary data suggest that proline can modulate root meristem size and, in turn, root growth. To evaluate this hypothesis we used a combination of genetic, pharmacological and molecular analyses, and showed that proline specifically affects root growth by modulating the size of the root meristem. The effects of proline on meristem size are parallel to, and independent from, hormonal pathways, and do not involve the expression of genes controlling cell differentiation at the transition zone (SHY2). On the contrary, proline appears to control cell division in early stages of postembryonic root development, as shown by the expression of the G2/M-specific CYCLINB1;1 gene and the G1/S-specific CYCLIND3;1 gene The overall data suggest that proline can modulate the size of root meristematic zone in Arabidopsis likely controlling cell division and, in turn, the ratio between cell division and cell differentiation

Marine litter tracking system: a case study with open-source technology and a citizen science-based approach

It is well established that rivers are amongst the most important carriers of the plastic pollution found in the oceans. However, the main processes contributing to plastic and debris fate through riparian systems is still poorly known and understood. The Marine Litter Drifter project from the Arno River aims at using modern consumer software and hardware technologies to track the trajectories and evolution at sea of real Anthropogenic Marine Debris (AMD) from rivers, with a specific focus on the Arno River, in Italy. Innovative and low cost “Marine Litter Trackers” (MLT) were designed, assembled and used in this framework as they are reliable, robust, self-powered and they present almost no maintenance costs. Furthermore, they can be built not only by those trained in the field but also by those with no specific expertise, including high school students, simply by following the instructions. Several dispersion experiments were successfully conducted using different types of trackers in different seasons and weather conditions. The maximum distance tracked was 2845 km for a period of 94 days. The activity at sea was integrated by lagrangian numerical models supporting the planning of the deployments and the recovery of the drifters. The models, in turn could benefit from the observed tracking data for calibration and validation and serve as tools to study and interpret the processes driving macro plastic displacement at sea. In this presentation we describe this activity and we discuss the dynamics of marine litter (ML) dispersion in the Tyrrhenian Sea on the basis of these integrated monitoring tools, as well as the potential of open-source approaches including the “citizen-science” perspective for both improving Big Data collection and educating/awareness-raising on AMD issues.PublishedVienna, Austria4A. Oceanografia e clim

Marine litter tracking system: a case study with open-source technology and a citizen science-based approach

&amp;lt;p&amp;gt;It is well established that rivers are amongst the most important carriers of the plastic pollution found in the oceans. However, the main processes contributing to plastic and debris fate through riparian systems is still poorly known and understood. The Marine Litter Drifter project from the Arno River aims at using modern consumer software and hardware technologies to track the trajectories and evolution at sea of real Anthropogenic Marine Debris (AMD) from rivers, with a specific focus on the Arno River, in Italy. Innovative and low cost &amp;amp;#8220;Marine Litter Trackers&amp;amp;#8221; (MLT) were designed, assembled and used in this framework as they are reliable, robust, self-powered and they present almost no maintenance costs. Furthermore, they can be built not only by those trained in the field but also by those with no specific expertise, including high school students, simply by following the instructions.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Several dispersion experiments were successfully conducted using different types of trackers in different seasons and weather conditions. The maximum distance tracked was 2845 km for a period of 94 days. The activity at sea was integrated by lagrangian numerical models supporting the planning of the deployments and the recovery of the drifters. The models, in turn could benefit from the observed tracking data for calibration and validation and serve as tools to study and interpret the processes driving macro plastic displacement at sea. In this presentation we describe this activity and we discuss the dynamics of marine litter (ML) dispersion in the Tyrrhenian Sea on the basis of these integrated monitoring tools, as well as the potential of open-source approaches including the &amp;amp;#8220;citizen-science&amp;amp;#8221; perspective for both improving Big Data collection and educating/awareness-raising on AMD issues.&amp;lt;/p&amp;gt;</jats:p

Proline is required for male gametophyte development in Arabidopsis

<p>Abstract</p> <p>Background</p> <p>In crosses between the proline-deficient mutant homozygous for <it>p5cs1</it> and heterozygous for <it>p5cs2 (p5cs1 p5cs2/P5CS2)</it>, used as male, and different Arabidopsis mutants, used as females, the <it>p5cs2</it> mutant allele was rarely transmitted to the outcrossed progeny, suggesting that the fertility of the male gametophyte carrying mutations in both <it>P5CS1</it> and <it>P5CS2</it> is severely compromised.</p> <p>Results</p> <p>To confirm the fertility defects of pollen from <it>p5cs1 p5cs2/P5CS2</it> mutants, transmission of mutant alleles through pollen was tested in two ways. First, the number of progeny inheriting a dominant sulfadiazine resistance marker linked to <it>p5cs2</it> was determined. Second, the number of <it>p5cs2/p5cs2</it> embryos was determined. A ratio of resistant to susceptible plantlets close to 50%, and the absence of aborted embryos were consistent with the hypothesis that the male gametophyte carrying both <it>p5cs1</it> and <it>p5cs2</it> alleles is rarely transmitted to the offspring. In addition, in reciprocal crosses with wild type, about 50% of the <it>p5cs2</it> mutant alleles were transmitted to the sporophytic generation when <it>p5cs1 p5cs2/P5CS2</it> was used as a female, while less than 1% of the <it>p5cs2</it> alleles could be transmitted to the outcrossed progeny when <it>p5cs1 p5cs2/P5CS2</it> was used as a male. Morphological and functional analysis of mutant pollen revealed a population of small, degenerated, and unviable pollen grains, indicating that the mutant homozygous for <it>p5cs1</it> and heterozygous for <it>p5cs2</it> is impaired in pollen development, and suggesting a role for proline in male gametophyte development. Consistent with these findings, we found that pollen from <it>p5cs1</it> homozygous mutants, display defects similar to, but less pronounced than pollen from <it>p5cs1 p5cs2/P5CS2</it> mutants. Finally, we show that pollen from <it>p5cs1 p5cs2/P5CS2</it> plants contains less proline than wild type and that exogenous proline supplied from the beginning of another development can partially complement both morphological and functional pollen defects.</p> <p>Conclusions</p> <p>Our data show that the development of the male gametophyte carrying mutations in both <it>P5CS1</it> and <it>P5CS2</it> is severely compromised, and indicate that proline is required for pollen development and transmission.</p

Role of Glutamate-Derived Amino Acids under Stress Conditions: The Case of Glutamine and Proline

A number of metabolic adaptive processes have been evolved in higher plants to cope with environmental stresses. Being sessile organisms unable to escape stressful conditions, plant survival is critically dependent by the rapid establishment of metabolic and physiologic responses that collectively attenuate or block the harmful effects of environmental injuries. Drought, cold and salt stress, in particular, are major threats for plant life, and cause, on a worldwide scale, dramatic losses in crop yields, especially in many developing countries and arid or semi-arid regions. The amino acids derived from glutamic acid, such as proline, γ-amino butyric acid (GABA), glutamine, arginine, as well as their close derivatives polyamines and nitric oxide (NO), play a special role in the metabolic adaptations of plants during abiotic stress. Glutamate itself seems to be not directly affected by stress conditions, but in reality plays an essential role as a donor of stress-related amino acids and metabolites as well as signal molecule involved in stress responses. Indeed most amino acids belonging to the glutamate family accumulate in large amounts under stress conditions and are thought to improve plant stress tolerance, although the molecular mechanisms through which these amino acids exert their action are still poorly understood. The study of the molecular and biochemical mechanisms by which this class of amino acids can improve plant tolerance to environmental stresses is of paramount importance in basic biology and can be regarded as a preliminary step towards the development of stress-tolerant and high-yield crop plants. The development of stress-tolerant crops of high productivity is a major issue in current research because of the increasing food demand of a growing world population, combined with the harmful effects of global warming, particularly drought, salinity and extreme temperatures. In this chapter the current state of the art of the glutamate-derived amino acids under stress conditions will be thoroughly revised and critically discussed with particular attention to the role of glutamine and proline for possible amelioration of yield and stress tolerance of agricultural crops

RAS specific protease induces irreversible growth arrest via p27 in several KRAS mutant colorectal cancer cell lines

AbstractRas-specific proteases to degrade RAS within cancer cells are under active development as an innovative strategy to treat tumorigenesis. The naturally occurring biological toxin effector called RAS/RAP1-specific endopeptidase (RRSP) is known to cleave all RAS within a cell, including HRAS, KRAS, NRAS and mutant KRAS G13D. Yet, our understanding of the mechanisms by which RRSP drives growth inhibition are unknown. Here, we demonstrate, using isogenic mouse fibroblasts expressing a single isoform of RAS or mutant KRAS, that RRSP equally inactivates all isoforms of RAS as well as the major oncogenic KRAS mutants. To investigate how RAS processing might lead to varying outcomes in cell fate within cancer cells, we tested RRSP against four colorectal cancer cell lines with a range of cell fates. While cell lines highly susceptible to RRSP (HCT116 and SW1463) undergo apoptosis, RRSP treatment of GP5d and SW620 cells induces G1 cell cycle arrest. In some cell lines, growth effects were dictated by rescued expression of the tumor suppressor protein p27 (Kip1). The ability of RRSP to irreversibly inhibit cancer cell growth highlights the antitumor potential of RRSP, and further warrants investigation as a potential anti-tumor therapeutic.</jats:p