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[EN] A large part of the production of tomato plants is grafted. Although it has recently been described that cell walls play an important role in tomato graft healing, the spatiotemporal dynamics of cell wall changes in this critical process remains largely unknown. The aim of this work was to immunolocalize changes in the major cell wall matrix components of autograft union tissues throughout the course of healing, from 1 to 20 days after grafting (DAG). Homogalacturonan was de novo synthetized and deposited in the cut edges, displaying the low methyl-esterified homogalacturonan a stronger labelling. Labelling of galactan side chains of rhamnogalacturonan increased until 8 DAG, although remarkably a set of cells at the graft union did not show labelling for this epitope. Changes in xylan immunolocalization were associated to the xylem vasculature development throughout, while those of xyloglucan revealed early synthesis at the cut edges. Arabinogalactan proteins increased up to 8 DAG and showed scion-rootstock asymmetry, with a higher extent in the scion. The combination of these changes appears to be related with the success of the autograft, specifically facilitating the adhesion phase between scion-rootstock tissues. This knowledge paves the way for improved grafting using methods that facilitate appropriate changes in the time and space dynamics of these cell wall compounds. SI Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

[EN] Grafting involves a sequence of modifications that may vary according to genotypes, grafting techniques and growing conditions. This process is often monitored using destructive methods, precluding the possibility of monitoring the entire process in the same grafted plant. The aim of this study was to test the effectiveness of two non-invasive methods—thermographic inference of transpiration and determination of chlorophyll quantum yields—for monitoring graft dynamics in tomato (Solanum lycopersicum L.) autografts and to compare the results with other reliable measures: mechanical resistance parameters and xylem water potential. The mechanical resistance of grafted plants steadily increased from 6 days after grafting (DAG), 4.90 ± 0.57 N/mm, to reach values similar to non-grafted plants at 16 DAG, 8.40 ± 1.78 N/mm. Water potential showed an early decrease (from −0.34 ± 0.16 MPa in non-grafted plants to −0.88 ± 0.07 MPa at 2 DAG), recovering at 4 DAG to reach pre-grafting values at 12–16 DAG. Thermographic inference of transpiration dynamics displayed comparable changes. Monitoring maximum and effective quantum yield in functional grafts showed a comparable pattern: an initial decline, followed by recovery from 6 DAG onwards. Correlation analyses revealed a significant correlation between variation in temperature (thermographic monitoring of transpiration), water potential (r = 0.87; p = 0.02) and maximum tensile force (r = 0.75; p = 0.05). Additionally, we found a significant correlation between maximum quantum yield and some mechanical parameters. In conclusion, thermography monitoring, and to a lesser extent maximum quantum yield measurements, accurately depict changes in key parameters in grafted plants and serve as potential timing indicators of graft regeneration, rendering them valuable tools for monitoring graft functionality SI Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

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Saxifraga paniculata is a subalpine succulent perennial plant arranged in a rosette that is usually found in shallow soil among limestone rocks. Stereoscopic, light and scanning electron microscopy...

Objetivou-se com o presente trabalho caracterizar e analisar aspectos ligados à sustentabilidade de propriedades leiteiras pertencentes a um assentamento de Reforma Agrária no centro-norte do Paraná. Foram analisadas 100 pequenas propriedades, vinculadas a “agricultura do tipo familiar”, no período de outubro de 2019 a março de 2020, por meio da aplicação de formulários semiestruturados, com finalidade de levantar dados a respeito de questões ambientais, econômicas, sociais, tecno-produtivas, sanidade de ordenha, manejo das pastagens e assistência técnica. Utilizou-se de técnicas de análise estatística descritiva e análise agregada. Os resultados mostram que dos 31 indicadores de sustentabilidade analisadas, 14 ficaram acima do limiar de sustentabilidade (pontuação 3 em escala de 1 a 5), enquanto 17 não atingiram esse limiar. Tais dados apontam para um provável problema de sobrevivência da pecuária leiteira em médio e longo prazo, caso não venha a ser desenvolvidas estratégias de apoio e soluções das fragilidades identificadas nesses sistemas produtivos.

Grafting is a technique applied to a considerable number of crops, with tomato standing out. However, this technique is limited by the obtaining of unfunctional grafts, which decrease the success rate and therefore the benefits achieved. The aim of this work was to analyze the failure in intraspecific grafting of tomato plants, focusing on tissue development, cell wall defense reactions, and the distribution of starch and soluble sugars at the graft junction. The success rate in autografts was higher than that of homografts and heterografts. Unfunctional homografts and heterografts showed similar responses: absence of vascular reconnections and lack of adhesion between scion and rootstock, even though callus cell clusters and differentiation of new vasculature were produced. The scions of unfunctional grafts accumulated more starch and soluble sugars than the rootstocks, showing a strong asymmetry in the response. In addition, three types of deposits were observed in the cell walls of unfunctional grafts: lignin, suberin, and callose, with the combined accumulation of more than one of them being frequent, particularly lignin and suberin. These deposits apparently prevent adhesion and seem to be a major cause of graft failure.

Background. Despite the importance of grafting in agriculture, particularly in horticultural crops such as tomato (Solanum lycopersicum L.), the structural changes that occur during the establishment of a graft are little understood. Using histochemical techniques, the present work examines the progression of the structure of the graft junction in tomato plants over time.Results. At 10 days after grafting, the cell walls of the scion and rootstock in the area of the graft junction were thicker than usual, and undifferentiated cells appeared associated with the pre-existing vascular tissue. New vascular tissue appeared as branches arising from the pre-existing vasculature, as vascular pockets dispersed within the callus, and as the result of the transdifferentiation of parenchyma cells. Areas showing vascular connections between the scion and rootstock were also seen. Adventitious roots appeared on the scion, arising from the pre-existing vasculature. At 20 days, a great deal of vascular tissue was visible, along with large areas showing vascular connection. At 210 days, vestiges of the changes undergone were still visible. However, no adventitious roots persisted. Conclusions. The area of the graft junction undergoes modifications essential for adequate physiological functioning of grafted plant. The cell walls of the adhesion line change during the process. Pre-existing vasculature plays an important role in the appearance of callus tissue, new vascular cells, and adventitious roots. A long time later the tissues maintain vestiges of graft union development.

Plant cell walls provide essential functions in cell recognition, differentiation, adhesion and wound responses. Therefore, it is tempting to hypothesize that cell walls play a key role in grafting, but to date there are no quantitative studies targeting on cell wall changes during grafting. The aim of this work was to investigate the dynamics of pectic and hemicellulosic polysaccharides at the graft junctions in tomato homografts throughout the first 12 days after grafting. Cell wall fractionation, combined with ATR-FTIR spectroscopy and gas-chromatography, evidenced a marked increase in pectin content and a decrease in the degree of methyl-esterification of homogalacturonan in scion and rootstock throughout grafting. Also, recovery of tightly-bound hemicelluloses decreased at late times after grafting suggesting an increase of cross-linked hemicelluloses along grafting. In addition, immuno-dot assays revealed an increase in xyloglucan and arabinogalactan proteins in the first days after grafting, pointing to a presumed role in tissue adhesion-cohesion.