The risk of musculoskeletal disorders for workers due to repetitive movements during tomato harvesting

Tomatoes are the most common crop in Italy. The production cycle requires operations in the field and factory that can cause musculoskeletal disorders due to the repetitive movements of the upper limbs of the workers employed in the sorting phase. This research aims to evaluate these risks using the OCRA (occupational repetitive actions) index method This method is based firstly on the calculation of a maximum number of recommended actions, related to the way the operation is performed, and secondly on a comparison of the number of actions effectively carried out by the upper limb with the recommended calculated value. The results of the risk evaluation for workers who manually sort tomatoes during harvest showed a risk for the workers, with an exposure index greater than 20; the OCRA index defines an index higher than 3.5 as unacceptable. The present trend of replacing manual sorting onboard a vehicle with optical sorters seems to be appropriate to reduce the risk of work-related musculoskeletal disorders (WMSDs) and is supported from both a financial point of view and as a quality control measure.

The expression levels of three raft-associated molecules in cultivated vascular cells are dependent on culture conditions

Relaying a signal across the plasma membrane requires functional connections between the partner molecules. Membrane microdomains or lipid rafts provide an environment in which such specific interactions can take place. The integrity of these sites is often taken for granted when signalling pathways are investigated in cell culture. However, it is well known that smooth muscle and endothelial cells undergo cytoskeletal rearrangements during monolayer culturing. Likewise affected--and with potentially important consequences for signalling events--is the organization of the plasma membrane. The expression levels of three raft markers were massively upregulated, and raft-associated 5'-nucleotidase activity increased in conventional monolayer cultures as compared with a spheroidal coculture model, shown to promote the differentiation of endothelial cells. Our data point to a shift of raft components in monolayer cultures and demonstrate potential advantages of the spheroid coculture system for investigation of raft-mediated signalling events in endothelial cells.

Microsurgical and laser ablation analysis of leaf positioning and dorsoventral patterning in tomato

Leaves are arranged according to regular patterns, a phenomenon referred to as phyllotaxis. Important determinants of phyllotaxis are the divergence angle between successive leaves, and the size of the leaves relative to the shoot axis. Young leaf primordia are thought to provide positional information to the meristem, thereby influencing the positioning of new primordia and hence the divergence angle. On the contrary, the meristem signals to the primordia to establish their dorsoventral polarity, which is a prerequisite for the formation of a leaf blade. These concepts originate from classical microsurgical studies carried out between the 1920s and the 1970s. Even though these techniques have been abandoned in favor of genetic analysis, the resulting insights remain a cornerstone of plant developmental biology. Here, we employ new microsurgical techniques to reassess and extend the classical studies on phyllotaxis and leaf polarity. Previous experiments have indicated that the isolation of an incipient primordium by a tangential incision caused a change of divergence angle between the two subsequent primordia, indicating that pre-existing primordia influence further phyllotaxis. Here.. we repeat these experiments and compare them with the results of laser ablation of incipient primordia. Furthermore. we explore to what extent the different pre-existing primordia influence the size and position of new organs. and hence phyllotaxis. We propose that the two youngest primordia (P-1 and P-2) are sufficient for the approximate positioning of the incipient primordium (I-1), and therefore for the perpetuation of the generative spiral, whereas the direct contact neighbours of I-1 (P-2 and P-3) control its delimitation and hence its exact size and position. Finally. we report L I specific cell ablation experiments suggesting that the meristem L-1 layer is essential for the dorsoventral patterning of leaf primordia.

Domains of expansin gene expression define growth regions in the shoot apex of tomato

Expansins are members of a multigene family of extracellular proteins, which increase cell wall extensibility in vitro and thus are thought to be involved in cell expansion. The major significance of the presence of this large gene family may be that distinctly expressed genes can independently regulate cell expansion in place and time. Here we report on LeExp9, a new expansin gene from tomato, and compare its expression in the shoot tip with that of LeExp2 and LeExp18. LeExp18 gene is expressed in very young tissues of the tomato shoot apex and the transcript levels are upregulated in the incipient primordium. LeExp2 mRNA accumulated in more mature tissues and transcript levels correlated with cell elongation in the elongation zone. In situ hybridization experiments showed a uniform distribution of LeExp9 mRNA in submeristematic tissues. When gibberellin-deficient mutant tomatoes that lacked elongation of the internodes were treated with gibberellin, the phenotypic rescue was correlated with an increase in LeExp9 and LeExp2, but not LeExp18 levels. We propose that the three expansins define three distinct growing zones in the shoot tip. In the meristem proper, gibberellin-independent LeExp18 mediates the cell expansion that accompanies cell division. In the submeristematic zone, LeExp9 mediates cell expansion at a time that cell division comes to a halt. LeExp9 expression requires gibberellin but the hormone is not normally limiting. Finally, LeExp2 mediates cell elongation in young stem tissue. LeExp2 expression is limited by the available gibberellin. These data suggest that regulation of cell wall extensibility is controlled, at least in part, by differential regulation of expansin genes.

Microsurgical and laser ablation analysis of interactions between the zones and layers of the tomato shoot apical meristern

Plants exhibit life-long organogenic and histogenic activity in a specialised organ, the shoot apical meristem. Leaves and flowers are formed within the ring-shaped peripheral zone, which surrounds the central zone, the site of the stem cells. We have undertaken a series of high-precision laser ablation and microsurgical tissue removal experiments to test the functions of different parts of the tomato meristem, and to reveal their interactions. Ablation of the central zone led to ectopic expression of the WUSCHEL gene at the periphery, followed by the establishment of a new meristem centre. After the ablation of the central zone, organ formation continued without a lag. Thus, the central zone does not participate in organogenesis, except as the ultimate source of founder cells. Microsurgical removal of the external L-1 layer induced periclinal cell divisions and terminal differentiation in the subtending layers. In addition, no organs were initiated in areas devoid of L-1, demonstrating an important role of the L-1 in organogenesis. L-1 ablation had only local effects, an observation that is difficult to reconcile with phyllotaxis theories that invoke physical tension operating within the meristem as a whole. Finally, regeneration of L-1 cells was never observed after ablation. This shows that while the zones of the meristem show a remarkable capacity to regenerate after interference, elimination of the L-1 layer is irreparable and causes terminal differentiation.

The role of cytochromes P450 and peroxidases in the detoxification of sulphonated anthraquinones by rhubarb and common sorrel plants cultivated under hydroponic conditions

Sulphonated anthraquinones are precursors of many synthetic dyes and pigments, recalcitrant to biodegradation and thus not eliminated by classical wastewater treatments. In the development of a phytotreatment to remove sulphonated aromatic compounds from dye and textile industrial effluents, it has been shown that rhubarb (Rheum rabarbarum) and common sorrel (Rumex acetosa) are the most efficient plants. Both species, producing natural anthraquinones, not only accumulate, but also transform these xenobiotic chemicals. Even if the precise biochemical mechanisms involved in the detoxification of sulphonated anthraquinones are not yet understood, they probably have cross talks with secondary metabolism, redox processes and plant energy metabolism. The aim of the present study was to investigate the possible roles of cytochrome P450 monooxygenases and peroxidases in the detoxification of several sulphonated anthraquinones. Both plant species were cultivated in a greenhouse under hydroponic conditions, with or without sulphonated anthraquinones. Plants were harvested at different times and either microsomal or cytosolic fractions were prepared. The monooxygenase activity of cytochromes P450 toward several sulphonated anthraquinones was tested using a new method based on the fluorimetric detection of oxygen consumed during cytochromes P450-catalysed reactions. The activity of cytosolic peroxidases was measured by spectrophotometry, using guaiacol as a substrate. A significant activity of cytochromes P450 was detected in rhubarb leaves, while no (rhizome) or low (petioles and roots) activity was found in other parts of the plants. An induction of this enzyme was observed at the beginning of the exposition to sulphonated anthraquinones. The results also indicated that cytochromes P450 were able to accept as substrate the five sulphonated anthraquinones, with a higher activity toward AQ-2,6-SS (0.706 nkat/mg protein) and AQ-2-S (0.720 nkat/mg protein). An activity of the cytochromes P450 was also found in the leaves of common sorrel (1.212 nkat/mg protein (AQ-2,6-SS)), but no induction of the activity occurred after the exposition to the pollutant. The activity of peroxidases increased when rhubarb was cultivated in the presence of the five sulphonated anthraquinones (0.857 nkat/mg protein). Peroxidase activity was also detected in the leaves of the common sorrel (0.055 nkat/mg protein), but in this plant, no significant difference was found between plants cultivated with and without sulphonated anthraquinones. Results indicated that the activity of cytochromes P450 and peroxidases increased in rhubarb in the presence of sulphonated anthraquinones and were involved in their detoxification mechanisms. These results suggest the existence in rhubarb and common sorrel of specific mechanisms involved in the metabolism of sulphonated anthraquinones. Further investigation should be performed to find the next steps of this detoxification pathway. Besides these promising results for the phytotreatment of sulphonated anthraquinones, it will be of high interest to develop and test, at small scale, an experimental wastewater treatment system to determine its efficiency. On the other hand, these results reinforce the idea that natural biodiversity should be better studied to use the most appropriate species for the phytotreatment of a specific pollutant.

An automated method for mapping physical soil and water conservation structures on cultivated land using GIS and remote sensing techniques

An efficient and reliable automated model that can map physical Soil and Water Conservation (SWC) structures on cultivated land was developed using very high spatial resolution imagery obtained from Google Earth and ArcGIS, ERDAS IMAGINE, and SDC Morphology Toolbox for MATLAB and statistical techniques. The model was developed using the following procedures: (1) a high-pass spatial filter algorithm was applied to detect linear features, (2) morphological processing was used to remove unwanted linear features, (3) the raster format was vectorized, (4) the vectorized linear features were split per hectare (ha) and each line was then classified according to its compass direction, and (5) the sum of all vector lengths per class of direction per ha was calculated. Finally, the direction class with the greatest length was selected from each ha to predict the physical SWC structures. The model was calibrated and validated on the Ethiopian Highlands. The model correctly mapped 80% of the existing structures. The developed model was then tested at different sites with different topography. The results show that the developed model is feasible for automated mapping of physical SWC structures. Therefore, the model is useful for predicting and mapping physical SWC structures areas across diverse areas.

Localized Upregulation of a New Expansin Gene Predicts the Site of Leaf Formation in the Tomato Meristem

Expansins are extracellular proteins that increase plant cell wall extensibility in vitro and are thought to be involved in cell expansion. We showed in a previous study that administration of an exogenous expansin protein can trigger the initiation of leaflike structures on the shoot apical meristem of tomato. Here, we studied the expression patterns of two tomato expansin genes, LeExp2 and LeExp18. LeExp2 is preferentially expressed in expanding tissues, whereas LeExp18 is expressed preferentially in tissues with meristematic activity. In situ hybridization experiments showed that LeExp18 expression is elevated in a group of cells, called I1, which is the site of incipient leaf primordium initiation. Thus, LeExp18 expression is a molecular marker for leaf initiation, predicting the site of primordium formation at a time before histological changes can be detected. We propose a model for the regulation of phyllotaxis that postulates a crucial role for expansin in leaf primordium initiation.

Analysis of expansin-induced morphogenesis on the apical meristem of tomato

Our previous work has shown that localised activity of the cell-wall-loosening protein expansin is sufficient to induce primordia on the apical meristem of tomato, consistent with the hypothesis that tissue expansion plays a key role in leaf initiation. In this paper we describe the earliest morphogenic events visible on the surface of the apical meristem of tomato (Lycopersicon esculentum Mill.) following treatment with expansin and report on the spectrum of final structures formed. Our observations are consistent with a proposed primary function of expansin effecting morphogenesis via altered biophysical stress patterns in the meristem. The primordia induced by expansin do not complete the full program of leaf development. We present data indicating that one reason for this might be the inability of exogenous expansin to mimic the endogenous pattern of expansin activity in the meristem. These data provide the first detailed analysis at the cellular level of expansin action on living tissue, the first description of the spectrum of structures induced by expansin on the apical meristem, and give an insight into a potentially fundamental mechanism in plant development.

LeProT1, a Transporter for Proline, Glycine Betaine, and γ-Amino Butyric Acid in Tomato Pollen

During maturation, pollen undergoes a period of dehydration accompanied by the accumulation of compatible solutes.Solute import across the pollen plasma membrane, which occurs via proteinaceous transporters, is required to support pollen development and also for subsequent germination and pollen tube growth. Analysis of the free amino acid composition of various tissues in tomato revealed that the proline content in flowers was 60 times higher than in any other organ analyzed. Within the floral organs, proline was confined predominantly to pollen, where it represented >70 of total free amino acids. Uptake experiments demonstrated that mature as well as germinated pollen rapidly take up proline. To identify proline transporters in tomato pollen, we isolated genes homologous to Arabidopsis proline transporters. LeProT1 was specifically expressed both in mature and germinating pollen, as demonstrated by RNA in situ hybridization. Expression in a yeast mutant demonstrated that LeProT1 transports proline and γ-amino butyric acid with low affinity and glycine betaine with high affinity. Direct uptake and competition studies demonstrate that LeProT1 constitutes a general transporter for compatible solutes.