1,721,095 research outputs found
Aspetti nutraceutici ed allergenici legati al consumo di frutta
No full textLa conoscenza approfondita delle componenti funzionali della frutta rappresenta un requisito fondamentale per la messa a punto di forme ipoallergeniche biologicamente attive e di peptidi ricombinanti da impiegare nelle vaccinazioni. La ricerca in questo campo risulta estremamente utile per la messa a punto dei futuri strumenti diagnostici e terapeutici nell'ambito delle allergie alimentari. Transgenesi o valutazione della biodiversità disponibile accompagnata a nuove tecniche colturali? I pregi e i difetti insiti in ognuna delle tecnologie applicative
Small GTPases in vesicle trafficking
No full textPlant small GTPases belonging to the Rop, Arf, and Rab families are regulators of vesicle trafficking. Rop GTPases regulate actin dynamics and modulate H2O2 production in polar cell growth and pathogen defence. A candidate Rop GDP to Rob GTP exchange factor (RopGEF) SPIKE1 is involved in the morphogenesis of leaf epidermal cells. The ArfGEF GNOM regulates the endosomal recycling of the PIN proteins, which are involved in polar auxin transport. Intracellular localisation of small GTPases and functional studies using dominant mutant versions of Arf and Rab GTPases are defining novel plant-specific membrane compartments, especially those that participate in endosomal vesicle trafficking
Evaluation of RNA Extraction Methods and Identification of Putative Reference Genes for Real-Time Quantitative Polymerase Chain Reaction Expression Studies on Olive (Olea europaeaL.) Fruits
No full textGenome wide transcriptomic surveys together with targeted molecular studies are uncovering an ever increasing number of differentially expressed genes in relation to agriculturally relevant processes in olive (Olea europaea L). These data need to be supported by quantitative approaches enabling the precise estimation of transcript abundance. qPCR being the most widely adopted technique for mRNA quantification, preliminary work needs to be done to set up robust methods for extraction of fully functional RNA and for the identification of the best reference genes to obtain reliable quantification of transcripts. In this work, we have assessed different methods for their suitability for RNA extraction from olive fruits and leaves and we have evaluated thirteen potential candidate reference genes on 21 RNA samples belonging to fruit developmental/ripening series and to leaves subjected to wounding. By using two different algorithms, GAPDH2 and PP2A1 were identified as the best reference genes for olive fruit development and ripening, and their effectiveness for normalization of expression of two ripening marker genes was demonstrated
The Yes and No of the Ethylene Involvement in Abscission
Full text linkAbscission has significant implications in agriculture and several efforts have been addressed by researchers to understand its regulatory steps in both model and crop species. Among the main players in abscission, ethylene has exhibited some fascinating features, in that it was shown to be involved at different stages of abscission induction and, in some cases, with interesting roles also within the abscising organ at the very early stages of the process. This review summarizes the current knowledge about the role of ethylene both at the level of the abscission zone and within the shedding organ, pointing out the missing pieces of the very complicated puzzle of the abscission process in the different species
The effects of a neighbour and its identity on roots’ plastic growth
Full text linkPlant responses to the presence of neighbours and social interactions between them have the potential to alter fundamental aspects of plants' evolution, persistence, and coexistence. The present study employs a novel approach to investigate the three-dimensional movement of root tips in response to a neighbouring plant of the same or different species. We collected data from maize and pea plants in three experimental conditions: (i) individual condition, in which plants grew without neighbours; (ii) social growing condition with a conspecific neighbour, in which plants grew in the presence of another plant of the same species; and (iii) social growing with a heterospecific neighbour, in which plants grew in the presence of another plant of a different species. The results indicate that roots display a more pronounced 'exploratory' behaviour when growing under social conditions. For both maize and pea plants, a higher incidence of aggregative behaviour (primary root moving towards the neighbour) was observed when plants grew near a conspecific when compared with an heterospecific neighbour. According to our analyses, roots showing aggregative behaviour seem to detect the neighbouring root with a good level of geometrical precision as shown by the observed directional movement. We contend that this study provides for the first time quantitative information on the modulation of kinematic and oscillatory features of root movements, which are vital for a deeper understanding of plants' below-ground interactions
Ethylene-responsive genes are differentially regulated during abscission, organ senescence and wounding in peach (Prunus persica)
No full textEthylene-responsive genes from peach (Prunes persica, L. Batsch) were isolated by differential screening of a cDNA library constructed from abscission zones in which cell separation had been evoked by treatment with the ethylene analogue propylene. DNA and deduced protein sequences of four selected clones, termed Prunus persica Abscission zone (PpAz), revealed homology to thaumatin-like proteins (PpAz8 and PpAz44), to proteins belonging to the PR4 class of pathogenesis-related (PR) proteins (PpAz89), and to fungal and plant beta-D-xylosidases (PpAz152). Expression analyses conducted on embrioctomized and CEPA-treated fruitlets as well as on fruit explants have shown that PpAz8, PpAz44 and PpAz89 are preferentially transcribed in the cells of the fruit abscission zone rather than in the non-zone tissues. The PpAz152 transcript showed a different accumulation pattern being consistently and promptly induced by wounding and only slightly stimulated by propylene. By contrast, a complex pattern of transcript accumulation was found for the four genes in response to the wounding of leaves and during organ development and senescence. Based on this evidence, the existence of multiple regulatory pathways underlying the differential expression of the four PpAz genes in the different tissues and physiological processes is hypothesized
Transcriptional signatures associated with apple fruitlet abscission
No full textApple (Malus x domestica L. Borkh) represents an interesting model tree crop for studying fruit abscission. The physiological fruitlet drop occurring in this species can be easily magnified by using thinning chemicals, such as benzyladenine (BA), in order to obtain fruits with improved quality and marketability. Despite the economical importance of this process, the molecular determinants of apple fruitlet abscission are still unknown. In the present research, BA was used to obtain fruitlet populations with different abscission potentials, to be analysed by means of a 30,419 oligonucleotide microarray set up starting from about 256,000 expressed sequence tag (EST) sequences available in public database. A dedicated bioinformatic pipeline was created to cluster and assemble the available ESTs into temptative unigenes that were spotted by means of the CombiMatrix technology. RNAs were extracted from cortex and seed of apple fruitlets sampled over a 4-day timecourse, during which BA triggers fruit drop, and used for microarray hybridisation. Transcriptomic profiles of persisting and abscising fruitlets were tested for statistical association with abscission potential, allowing to identify molecular signatures strictly related to fruit destiny with P < 0.001. A hypothetical model for apple fruitlet abscission was obtained by putting together available transcriptomic and metabolomic data. According to this model, BA treatment would establish a nutritional stress within the tree that is primarily perceived by the fruitlet cortex whose growth is inhibited. In weaker fruits, this stress is soon transduced to the seed via sugar signalling and hormones, followed by a block of embryogenesis and the consequent activation of the abscission zone. The molecular markers herein discovered may be used as diagnostic tools for the early identification of the self- or chemical-thinning aptitude of apple cultivars. Moreover, the functional characterization of markers with the best statistical scores will allow to shed light on the early cellular processes triggering apple fruitlet abscission
Roles of Ethylene Production and Ethylene Receptor Expression in Regulating Apple Fruitlet Abscission
Full text linkApple (Malus × domestica) is increasingly being considered an interesting model species for studying early fruit development, during which an extremely relevant phenomenon, fruitlet abscission, may occur as a response to both endogenous and/or exogenous cues. Several studies were carried out shedding light on the main physiological and molecular events leading to the selective release of lateral fruitlets within a corymb, either occurring naturally or as a result of a thinning treatment. Several studies pointed out a clear association between a rise of ethylene biosynthetic levels in the fruitlet and its tendency to abscise. A direct mechanistic link, however, has not yet been established between this gaseous hormone and the generation of the abscission signal within the fruit. In this work, the role of ethylene during the very early stages of abscission induction was investigated in fruitlet populations with different abscission potentials due either to the natural correlative inhibitions determining the so-called physiological fruit drop or to a well-tested thinning treatment performed with the cytokinin benzyladenine. A crucial role was ascribed to the ratio between the ethylene produced by the cortex and the expression of ethylene receptor genes in the seed. This ratio would determine the final probability to abscise. A working model has been proposed consistent with the differential distribution of four receptor transcripts within the seed, which resembles a spatially progressive cell-specific immune-like mechanism evolved by apple to protect the embryo from harmful ethylene
Ethylene biosynthesis in peach fruitlet abscission
No full textEthylene biosynthesis was studied in the peach (Prunus persica L. Batsch) fruitlet abscission zone (AZ), located between pedicel and pericarp and responsible for the shedding of the fruit, Explants, made up of the abscission layer and small parts of pedicel and pericarp, were flushed with air or air + propylene (500 cm(3) m(-3)) for up to 72 h, Parameters of ethylene biosynthesis were monitored in excised zone and non-zone tissues. Both treatments induced an increase of ethylene biosynthesis in all tissues examined and a climacteric-like behaviour was observed: ethylene evolution peaked at 12 and 48 h in air + propylene and air, respectively. The activity of 1-aminocyclopropane-1-carboxylate oxidase (ACO) and related transcript accumulation paralleled ethylene evolution. Furthermore a decreasing gradient, in terms of ethylene production, ACO activity and mRNA accumulation was in general observed moving from the distal (pericarp side) to the proximal (pedicel side) non-zone, through the abscission zone. The content of 1-aminocyclopropane-1-carboxylate (ACC) showed significant difference among treatments only at 12 h of air + propylene flushing in AZ3 and non-zones, but no difference in terms of ACC synthase transcript and related polypeptide accumulation was observed. Endo-beta-1,4-glucanase (EG), the cell mall hydrolase involved in cell separation, appeared to be up-regulated by propylene and its activity was almost exclusively confined to the abscission layer, Similarly, EG transcript accumulation occurred in zone but not in non-zone tissues. In air-treated and air + propylene-treated explants the ethylene climacteric preceded the increase of EG activity and the cell separation at the level of the abscission zone
Identificazione dei geni coinvolti nell’induzione dell’abscissione in melo (Malus domestica L. Borkh) tramite l’impiego di un microarray 30k
No full textL’abscissione dei frutticini di melo (Malus domestica L. Borkh) è il risultato di complesse interazioni sia ormonali che metaboliche, nell’ambito delle quali etilene e auxina rivestono un ruolo fondamentale nel controllare il distacco del frutto dalla pianta. Nell’ambito del corimbo, i frutti laterali che presentano ritmi di crescita ridotti sono soggetti ad una cascola più consistente rispetto al frutto centrale che, a seguito di una fioritura più precoce, cresce in un contesto di minor competizione. La cascola naturale dei frutticini risulta, tuttavia, insufficiente ad assicurare una produzione ottimale di frutti ed è quindi richiesto l’impiego di diradanti chimici allo scopo di magnificarne gli effetti ed ottenere così una produzione adatta alle esigenze del mercato. Specifici esperimenti sono stati condotti al fine di determinare gli eventi molecolari coinvolti nell’induzione dell’abscissione. A tale scopo, tramite l’impiego della benziladenina (BA), una citochinina impiegata come diradante chimico, è stata amplificata la cascola naturale e, sulla base di tre intervalli dimensionali, sono stati campionati i frutti laterali e centrali, trattati e non trattati, ottenendo così popolazioni di frutticini con potenziali di abscissione differenziali. Gli RNA estratti da cortex e semi di tali campioni sono stati utilizzati per l’analisi microarray, condotta utilizzando un vetrino allestito con la tecnologia Combimatrix sul quale sono stati spottati più di 30.000 geni, assemblati a partire dalle ESTs di melo disponibili nei database pubblici. L’analisi trascrittomica ha portato all’identificazione di geni differenzialmente espressi in maniera specifica nei frutti con alto potenziale di abscissione. Per quanto riguarda la cortex 165 e 27 geni sono risultati, rispettivamente, stimolati e repressi durante l’induzione della cascola. All’interno di questo pool genico sono stati individuati geni coinvolti nella biosintesi e nel metabolismo ormonale (GA2-ossidasi, IAA-idrolasi), nella percezione (GID1, BAK1) e nella trasduzione (EIL2, ARF3) del segnale ormonale, nella degradazione della parete cellulare (estensina, pectato-liasi, endoglucanasi), nel metabolismo degli zuccheri (fruttosio bisfosfato aldolasi, invertasi acida vacuolare, saccarosio-sintasi) e numerosi fattori di trascrizione (WRKY, MYB, MYC, NAC). L’analisi del trascrittoma di seme ha permesso di isolare 15 e 13 trascritti rispettivamente stimolati o repressi durante l’induzione dell’abscissione, tra i quali alcuni coinvolti nel metabolismo dei carboidrati (fruttosio bisfosfatasi, glucosil-idrolasi), una chinasi proteica e un fattore di trascrizione di tipo MADS. Analisi di validazione del profilo di espressione di tali geni, tuttora in corso, consentiranno di identificare gli elementi molecolari chiave che controllano le fasi precoci dell’abscissione in melo
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