Il ruolo di TAF12B e UVR3 nel ciclo circadiano dei vegetali

The book goes over the studies carried out on the circadian oscillators in plants, performed using the model plant Arabidopsis thaliana. The plant's oscillators seem to include similar components to those described for other model organisms. A bioinformatic analysis on the Arabidopsis genome found the genes TAF12b, At1g17440 and UVR3, At3g15620. Both the genes were cloned with the GFP green fluorescent protein in order to locate this protein at cell level. Furthermore, Arabidopsis SALK line plants were grown and selected, mutating the genes in question, and in parallel gene expression tests were performed on the main circadian rhythm genes in order to monitor their expression both in conditions of alternating light and dark, and in constant conditions. From the data that has emerged to date it seems that both genes are involved in the Arabidopsis's circadian rhythms

Isoprene Emission Influences the Proteomic Profile of Arabidopsis Plants under Well-Watered and Drought-Stress Conditions

Isoprene is a small lipophilic molecule synthesized in plastids and abundantly released into the atmosphere. Isoprene\u2010emitting plants are better protected against abiotic stresses, but the mechanism of action of isoprene is still under debate. In this study, we compared the physiological responses and proteomic profiles of Arabidopsis which express the isoprene synthase (ISPS) gene and emit isoprene with those of non\u2010emitting plants under both drought\u2010stress (DS) and well\u2010watered (WW) conditions. We aimed to investigate whether isoprene\u2010emitting plants displayed a different proteomic profile that is consistent with the metabolic changes already reported. Only ISPS DS plants were able to maintain the same photosynthesis and fresh weight of WW plants. LC\u2013 MS/MS\u2010based proteomic analysis revealed changes in protein abundance that were dependent on the capacity for emitting isoprene in addition to those caused by the DS. The majority of the proteins changed in response to the interaction between DS and isoprene emission. These include proteins that are associated with the activation of secondary metabolisms leading to ABA, trehalose, and proline accumulations. Overall, our proteomic data suggest that isoprene exerts its protective mechanism at different levels: under drought stress, isoprene affects the abundance of chloroplast proteins, confirming a strong direct or indirect antioxidant action and also modulates signaling and hormone pathways, especially those controlling ABA synthesis. Unexpectedly, isoprene also alters membrane trafficking

Il ruolo di TAF12B e UVR3 nel ciclo circadiano dei vegetali

The book goes over the studies carried out on the circadian oscillators in plants, performed using the model plant Arabidopsis thaliana. The plant\u27s oscillators seem to include similar components to those described for other model organisms. A bioinformatic analysis on the Arabidopsis genome found the genes TAF12b, At1g17440 and UVR3, At3g15620. Both the genes were cloned with the GFP green fluorescent protein in order to locate this protein at cell level. Furthermore, Arabidopsis SALK line plants were grown and selected, mutating the genes in question, and in parallel gene expression tests were performed on the main circadian rhythm genes in order to monitor their expression both in conditions of alternating light and dark, and in constant conditions. From the data that has emerged to date it seems that both genes are involved in the Arabidopsis\u27s circadian rhythms.Il volume ripercorre gli studi effettuati sugli oscillatori circadiani nelle piante che sono stati condotti usando la pianta modello Arabidopsis thaliana. Gli oscillatori della pianta sembrano comprendere componenti analoghi a quelli descritti per altri organismi modello. Da un\u27analisi bioinformatica sul genoma Arabidopsis sono stati trovati i geni TAF12b, At1g17440 e UVR3, At3g15620. Sono stati clonati entrambi i geni con la proteina fluorescente GFP (Green Flourescent Protein), al fine di individuare la localizzazione di questa proteina a livello cellulare. Inoltre sono state allevate e selezionate piantine di Arabidopsis SALK line, mutanti per i geni di interesse e in parallelo sono state condotte prove di espressione genica dei principali geni del ritmo circadiano, in modo da monitorarne l\u27espressione sia in condizioni di alternanza luce/buio sia in condizioni costanti. Dai dati emersi fino ad oggi sembra che entrambi i geni siano coinvolti nei ritmi circadiani di Arabidopsis

Isoprene: An Antioxidant Itself or a Molecule with Multiple Regulatory Functions in Plants?

Isoprene (C5H8) is a small lipophilic, volatile organic compound (VOC), synthesized in chloroplasts of plants through the photosynthesis-dependent 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. Isoprene-emitting plants are better protected against thermal and oxidative stresses but only about 20% of the terrestrial plants are able to synthesize isoprene. Many studies have been performed to understand the still elusive isoprene protective mechanism. Isoprene reacts with, and quenches, many harmful reactive oxygen species (ROS) like singlet oxygen (1O2). A role for isoprene as antioxidant, made possible by its reduced state and conjugated double bonds, has been often suggested, and sometimes demonstrated. However, as isoprene is present at very low concentrations compared to other molecules, its antioxidant role is still controversial. Here we review updated evidences on the function(s) of isoprene, and outline contrasting indications on whether isoprene is an antioxidant directly scavenging ROS, or a membrane strengthener, or a modulator of genomic, proteomic and metabolomic profiles (perhaps as a secondary effect of ROS removal) eventually leading to priming of antioxidant plant defenses, or a signal of stress for neighbor plants alike other VOCs, or a hormone-like molecule, controlling the metabolic flux of other hormones made by the MEP pathway, or acting itself as a growth and development hormone

Plant growth promotion by the interaction of a novel synthetic small molecule with GA‐DELLA function

Synthesized small molecules are useful as tools to investigate hormonal signaling involved in plant growth and development. They are also important as agrochemicals to promote beneficial properties of crops in the field. We describe here the synthesis and mode of action of a novel growth-promoting chemical, A1. A1 stimulates enhanced growth in both shoot and root tissues of plants, acting by increasing both dry and fresh weight. This suggests that A1 not only promotes uptake of water but also increases production of cellular material. A1 treatment of Arabidopsisleads to the degradation of DELLA growth-inhibitory proteins suggesting that A1-mediated growth promotion is dependent upon this mechanism. We performed genetic analysis to confirm this and further dissect the mechanism of A1 action upon growth in Arabidopsis. A quintuple dellamutant was insensitive to A1, confirming that the mode of action was indeed via a DELLA-dependent mechanism. The ga1-5gibberellin synthesis mutant was similarly insensitive, suggesting that to promote growth in ArabidopsisA1 requires the presence of endogenous gibberellins. This was further suggested by the observation that double mutants of GID1 gibberellin receptor genes were insensitive to A1. Taken together, our data suggest that A1 acts to enhance sensitivity to endogenous gibberellins thus leading to observed enhanced growth via DELLA degradation. A1 and related compounds will be useful to identify novel signaling components involved in plant growth and development, and as agrochemicals suitable for a wide range of crop species

Flavonoids as Antioxidants and Developmental Regulators: Relative Significance in Plants and Humans

Abstract: Phenylpropanoids, particularly flavonoids have been recently suggested as playing primary antioxidant functions in the responses of plants to a wide range of abiotic stresses. Furthermore, flavonoids are effective endogenous regulators of auxin movement, thus behaving as developmental regulators. Flavonoids are capable of controlling the development of individual organs and the whole-plant; and, hence, to contribute to stress-induced morphogenic responses of plants. The significance of flavonoids as scavengers of reactive oxygen species (ROS) in humans has been recently questioned, based on the observation that the flavonoid concentration in plasma and most tissues is too low to effectively reduce ROS. Instead, flavonoids may play key roles as signaling molecules in mammals, through their ability to interact with a wide range of protein kinases, including mitogen-activated protein kinases (MAPK), that supersede key steps of cell growth and differentiation. Here we discuss about the relative significance of flavonoids as reducing agents and signaling molecules in plants and humans. We show that structural features conferring ROS-scavenger ability to flavonoids are also required t