The Pneumatron: An automated pneumatic apparatus for estimating xylem vulnerability to embolism at high temporal resolution.

Xylem vulnerability to embolism represents an important trait to determine species distribution patterns and drought resistance. However, estimating embolism resistance frequently requires time-consuming and ambiguous hydraulic lab measurements. Based on a recently developed pneumatic method, we present and test the "Pneumatron", a device that generates high time-resolution and fully automated vulnerability curves. Embolism resistance is estimated by applying a partial vacuum to extract air from an excised xylem sample, while monitoring the pressure change over time. Although the amount of gas extracted is strongly correlated with the percentage loss of xylem conductivity, validation of the Pneumatron was performed by comparison with the optical method for Eucalyptus camaldulensis leaves. The Pneumatron improved the precision of the pneumatic method considerably, facilitating the detection of small differences in the (percentage of air discharged [PAD] < 0.47%). Hence, the Pneumatron can directly measure the 50% PAD without any fitting of vulnerability curves. PAD and embolism frequency based on the optical method were strongly correlated (r2 = 0.93) for E. camaldulensis. By providing an open source platform, the Pneumatron represents an easy, low-cost, and powerful tool for field measurements, which can significantly improve our understanding of plant-water relations and the mechanisms behind embolism.

Genome-wide analysis of AGO, DCL and RDR gene families reveals RNA-directed DNA methylation is involved in fruit abscission in Citrus sinensis.

BACKGROUND: Small RNAs regulate a wide variety of processes in plants, from organ development to both biotic and abiotic stress response. Being master regulators in genetic networks, their biogenesis and action is a fundamental aspect to characterize in order to understand plant growth and development. Three main gene families are critical components of RNA silencing: DICER-LIKE (DCL), ARGONAUTE (AGO) and RNA-DEPENDENT RNA POLYMERASE (RDR). Even though they have been characterized in other plant species, there is no information about these gene families in Citrus sinensis, one of the most important fruit species from both economical and nutritional reasons. While small RNAs have been implicated in the regulation of multiple aspects of plant growth and development, their role in the abscission process has not been characterized yet. RESULTS: Using genome-wide analysis and a phylogenetic approach, we identified a total of 13 AGO, 5 DCL and 7 RDR genes. We characterized their expression patterns in root, leaf, flesh, peel and embryo samples using RNA-seq data. Moreover, we studied their role in fruit abscission through gene expression analysis in fruit rind compared to abscission zone from samples obtained by laser capture microdissection. Interestingly, we determined that the expression of several RNA silencing factors are down-regulated in fruit abscission zone, being particularly represented gene components of the RNA-dependent DNA Methylation pathway, indicating that repression of this process is necessary for fruit abscission to take place in Citrus sinensis. CONCLUSIONS: The members of these 3 families present characteristic conserved domains and distinct expression patterns. We provide a detailed analysis of the members of these families and improved the annotation of some of these genes based on RNA-seq data. Our data suggests that the RNA-dependent DNA Methylation pathway is involved in the important fruit abscission process in C. sinensis.

HVA22 from citrus: A small gene family whose some members are involved in plant response to abiotic stress.

The HVA22 gene has been isolated for the first time from the aleurone layer of barley (Hordeum vulgare). Here, we characterized the HVA22 family from citrus (C. clementina and C. sinensis). Twelve genes, 6 in each species, were identified as well as duplication events for some of them. The ORF size ranged from 235 to 804 bp and the protein molecular weight from 94 to 267 kDa. All the citrus HVA22 protein presented transmembrane location and conserved TB2/DP1/HVA22 region. Phylogenetic and gene expression analyses suggested that some citrus HVA22 play a role in flower and fruit development, and that gene expression may be regulated by hormone or environmental conditions. Other regulation levels were also predicted, such as alternative splicing and post-translational modifications. The overall data indicated that citrus HVA22 may be involved in vesicular traffic in stressed cells, and that CcHVA22d could be involved in dehydration tolerance.

Spatiotemporal association between the mite Brevipalpus yothersi and Citrus leprosis virus C in orange orchards.

Citrus leprosis virus C (CiLV-C) is an economically important pathogen and the main causative agent of leprosis disease in citrus orchards. The main vector of this disease, the mite Brevipalpus yothersi, is widely distributed in Mexican orchards on a wide range of citrus species. Despite the importance of both the virus and the mite, field studies recording their occurrence and co-occurrence are practically non-existent. We systematically sampled orange orchards for both CiLV-C and B. yothersi throughout the year. The distribution of the CiLV-C and B. yothersi was evaluated on each sampling occasion and their spatiotemporal associations were determined. Specifically, 100-112 orange trees, distributed in 18 rows (five or six trees per row), were sampled monthly between March 2017 and February 2018 (11 sampling dates). Twenty leaves per tree were sampled on each occasion. The number of mites per tree and the percentage of leaves per tree with disease symptoms were recorded. On each sampling occasion, spatiotemporal associations between mites and disease were determined using the Spatial Analysis by Distance Indices (SADIE) method. CiLV-C and B. yothersi were identified using molecular methods. Throughout the study, the distribution of CiLV-C was aggregated and the distribution of B. yothersi was random. No association was found between the virus and the mite on any of the sampling dates. In total, 173 mites were collected, but only 43 mites were found to be carrying CiLV-C. The reason for this lack of association between the virus and the mite, as well as the impact of our findings on the epidemiology of the disease in orange orchards, are discussed.

Rootstock-induced molecular responses associated with drought tolerance in sweet orange as revealed by RNA-Seq.

BACKGROUND: Citrus plants are commercially propagated by grafting, with the rootstock variety influencing a number of horticultural traits, including drought tolerance. Among the different rootstock varieties available for citrus propagation, 'Rangpur' lime is known to confer enhanced tolerance to drought as compared to other citrus rootstocks. The objective of this study was to investigate the poorly understood molecular responses underlying the rootstock-induced drought tolerance in sweet orange. RESULTS: RNA-Seq transcriptome analysis was carried out in leaves of sweet orange grafted on 'Rangpur' lime subjected to control and drought-stress treatments, under greenhouse conditions, using the Illumina HiSeq platform. A total of 41,827 unique transcripts were identified, among which 1764 transcripts showed significant variation (P ≤ 0.001) between the treatments, with 1081 genes induced and 683 repressed by drought-stress treatment. The transcripts were distributed in 44 different categories of cellular component, molecular function and biological process. Several genes related to cell metabolism, including those involved in the metabolisms of cell wall, carbohydrates and antioxidants, light reactions, biotic and abiotic stress responses, as well as genes coding for transcription factors (TFs), protein kinases (PKs) and proteins involved in the abscisic acid (ABA) and ethylene signaling pathways, were differentially regulated by drought stress. RNA-Seq data were validated by quantitative real-time PCR (qPCR) analysis and comparative analysis of expression of the selected genes between sweet orange grafted on drought-tolerant and -sensitive rootstocks revealed new candidate genes for drought tolerance in citrus. CONCLUSIONS: In conclusion, our results showed that only a relatively small but functionally diverse fraction of the sweet orange transcriptome, with functions in metabolism, cellular responses and regulation, was differentially regulated by drought stress. The data suggest that the rootstock-induced drought tolerance in sweet orange includes the transcriptional activation of genes related to the cell wall, soluble carbohydrate and antioxidant metabolisms, biotic and abiotic stress responses, TFs, PKs and ABA signaling pathway, and the downregulation of genes involved in the starch metabolism, light reactions and ethylene signaling. Future efforts to elucidate their functional roles and explore their potential in the citrus genetic improvement should benefit from this data.

Injúrias mecânicas na qualidade pós-colheita de laranja Rosa armazenada sob condição ambiente / Mechanical injuries in post-harvest quality of orange "Rosa" stored on condition environment

In Postharvest there is hardly an improvement of the harvested product quality and, at maximum can maintain its quality for some period of time. The injuries which cause damage in postharvest can be mechanical, physiological and caused by pathogens due to inadequate practices and driving culture in the field and during harvest, transport and / or packaging. The present study aimed to characterize the damage postharvest fruit orange type Rosa after suffering mechanical damage by cutting, compression and impact. The experiment was conducted in a completely randomized design in a factorial consisting of two factors: damage to fruit (cut, compression, impact and control) and storage period (3, 7, 10, 14, 17, 21 and 24 days). All physicochemical analyzes were performed with three replicates in triplicate. Three types of mechanical injury were applied: impact, compression and cutting, and the control treatment were not received any kind of damage. Every three days we assessed fruit on the content of soluble solids, pH, titratable acidity, weight loss and visual evaluation. The control treatment showed the lowest average mass loss, and treatment showed the greatest weight loss was the damage by cutting treatment. For variable soluble solids damage by impact treatment showed the highest values soluble solids. For the variable appearance of the fruit, the witness showed better visual quality.

Em pós-colheita dificilmente há melhoria da qualidade de um produto colhido sendo que, no máximo é possível manter a sua qualidade por algum período de tempo. As injúrias resultam em danos em pós-colheita podem ser mecânicas, fisiológicas e provocadas por patógenos, sendo decorrentes de práticas inadequadas de condução da cultura no campo e durante a colheita, transporte e/ou embalagem. O presente trabalho teve como objetivo caracterizar os danos pós-colheita de frutos de laranja do tipo Rosa, após sofrerem danos mecânicos por corte, compressão e impacto. O experimento foi conduzido em delineamento experimental inteiramente casualizado, em esquema fatorial composto por dois fatores: danos causados nos frutos (corte, compressão, impacto e testemunha) e período de conservação (3, 7, 10, 14, 17, 21 e 24 dias). Todas as análises físico-químicas foram realizadas com três repetições e em triplicata. A cada três dias avaliou-se os frutos quanto ao teor de sólidos solúveis, pH, acidez titulável total, perda de massa e avaliação visual. O tratamento testemunha foi o que apresentou as menores médias de perda de massa, ocorrendo a maior perda quando se efetuou o dano por corte. Para a variável teor de sólidos solúveis o tratamento dano por impacto foi o que apresentou os maiores valores. Com relação a aparência dos frutos, a testemunha apresentou melhor qualidade visual.

Injúrias mecânicas na qualidade pós-colheita de laranja Rosa armazenada sob condição ambiente / Mechanical injuries in post-harvest quality of orange "Rosa" stored on condition environment

In Postharvest there is hardly an improvement of the harvested product quality and, at maximum can maintain its quality for some period of time. The injuries which cause damage in postharvest can be mechanical, physiological and caused by pathogens due to inadequate practices and driving culture in the field and during harvest, transport and / or packaging. The present study aimed to characterize the damage postharvest fruit orange type Rosa after suffering mechanical damage by cutting, compression and impact. The experiment was conducted in a completely randomized design in a factorial consisting of two factors: damage to fruit (cut, compression, impact and control) and storage period (3, 7, 10, 14, 17, 21 and 24 days). All physicochemical analyzes were performed with three replicates in triplicate. Three types of mechanical injury were applied: impact, compression and cutting, and the control treatment were not received any kind of damage. Every three days we assessed fruit on the content of soluble solids, pH, titratable acidity, weight loss and visual evaluation. The control treatment showed the lowest average mass loss, and treatment showed the greatest weight loss was the damage by cutting treatment. For variable soluble solids damage by impact treatment showed the highest values soluble solids. For the variable appearance of the fruit, the witness showed better visual quality.(AU)

Em pós-colheita dificilmente há melhoria da qualidade de um produto colhido sendo que, no máximo é possível manter a sua qualidade por algum período de tempo. As injúrias resultam em danos em pós-colheita podem ser mecânicas, fisiológicas e provocadas por patógenos, sendo decorrentes de práticas inadequadas de condução da cultura no campo e durante a colheita, transporte e/ou embalagem. O presente trabalho teve como objetivo caracterizar os danos pós-colheita de frutos de laranja do tipo Rosa, após sofrerem danos mecânicos por corte, compressão e impacto. O experimento foi conduzido em delineamento experimental inteiramente casualizado, em esquema fatorial composto por dois fatores: danos causados nos frutos (corte, compressão, impacto e testemunha) e período de conservação (3, 7, 10, 14, 17, 21 e 24 dias). Todas as análises físico-químicas foram realizadas com três repetições e em triplicata. A cada três dias avaliou-se os frutos quanto ao teor de sólidos solúveis, pH, acidez titulável total, perda de massa e avaliação visual. O tratamento testemunha foi o que apresentou as menores médias de perda de massa, ocorrendo a maior perda quando se efetuou o dano por corte. Para a variável teor de sólidos solúveis o tratamento dano por impacto foi o que apresentou os maiores valores. Com relação a aparência dos frutos, a testemunha apresentou melhor qualidade visual.(AU)

Cell wall modifications and ethylene-induced tolerance to non-chilling peel pitting in citrus fruit.

Non-chilling peel pitting (NCPP), a storage disorder resulting in the formation of depressed areas in the peel of many citrus cultivars, is reduced by ethylene treatments. We hypothesized that this effect may be associated with biochemical changes of cell wall components. Therefore, we extracted cell wall material from albedo and flavedo tissues of 'Navelate' oranges stored in air, conditioned with ethylene (2µLL(-1)) for 4 days and subsequently transferred to air, or continuously stored in an ethylene-enriched atmosphere (2µLL(-1)). Uronic acids and neutral sugars were extracted into five fractions enriched in specific wall polymers namely water-, CDTA-, Na2CO3-, and 1 and 4M KOH-soluble fractions. Pectin insolubilization was found in control fruit at long storage times. Ethylene treatments, alleviating NCPP, increased polyuronide solubility in the albedo and had a slight effect on the flavedo. Ethylene-treated fruit showed greater content of water-soluble neutral sugars and a larger proportion of hemicelluloses readily extractable with 1M KOH, with a concomitant reduction in the 4M KOH-soluble fraction. This suggests that the protective role of ethylene on NCPP is associated with an increased solubilization of the wall of albedo cells.

Evaluación del efecto de diferentes cepas de levadura (Montrachet, K1-V1116, EC-1118, 71B-1122 y IVC-GRE ®) y clarificantes sobre los atributos sensoriales del vino de naranja criolla (Citrus sinensis) / Evaluation of effect of various strains of yeast (Montrachet, K1-V1116, EC-1118, 71B-1122 y IVC-GRE ®) and clearer on the sensory attributes orange wine (Citrus sinensis)

En este trabajo se evaluó el efecto de diferentes cepas de levadura (Montrachet, K1-V1116, EC-1118, 71B-1122 y IVC-GRE ®) sobre los atributos sensoriales del vino de naranja. Estos atributos fueron medidos utilizando la escala modificada de UC Davis. En una prueba de ordenamiento para determinar el mejor tratamiento de clarificación se determinó que la gelatina por sí sola no causa efecto sobre el atributo apariencia general, la combinación de la gelatina y la microfiltración tienen un efecto positivo sobre la apariencia del vino de naranja. Los cinco vinos tratados con diferentes levaduras presentaron diferencias significativas sobre la puntuación total, acidez total, sabor y calidad en general. En términos del efecto de las levaduras, la evaluación sensorial realizada a los vinos mostró que el de naranja con la levadura K1-V1116 fue el que sobresalió en términos de puntuación en los promedios de casi todos los atributos analizados por el panel sensorial.

In this Wort was evaluated the effect of different types of strains of yeast (Montrachet, K1-V1116, EC-1118, 71B-1122 y IVC-GRE) over the sensorial attributes of orange wines were also studied. These attributes were measured in a modified scale of UC Davis. By using an order test in order to know the best cleared treatment, it was determined that gelatin by itself does not cause any effect over the general quality attribute, but the combination of gelatin and microfiltration, cause a positive effect over the orange wine appearance. The five wines treated with different yeasts presented significant differences on individual scores, total acidy, flavor and general quality of the UC Davis scale. The sensorial evaluation of wines showed that the yeast K1-V1116 produced the best rated orange wine. This wine was significantly different over many attributes when compared with the other wines evaluated by the sensorial panel.