Chemical composition and in vitro inhibitory effects of essential oils from fruit peel of three Citrus species and limonene on mycelial growth of Sclerotinia sclerotiorum / Composição química e efeito inibitório in vitro dos óleos essenciais das cascas dos frutos de três espécies de Citrus e do limoneno sobre o crescimento micelial de Sclerotinia sclerotiorum

Essential oils (EO) from aromatic and medicinal plants generally perform a diverse range of biological activities because they have several active constituents that work in different mechanisms of action. EO from Citrus peel have an impressive range of food and medicinal uses, besides other applications. EO from Citrus reticulata, C. sinensis and C. deliciosa were extracted from fruit peel and analyzed by GC-MS. The major constituent of EO under evaluation was limonene, whose concentrations were 98.54%, 91.65% and 91.27% for C. sinensis, C. reticulata and C. deliciosa, respectively. The highest potential of inhibition of mycelial growth was observed when the oil dose was 300 L. Citrus oils inhibited fungus growth in 82.91% (C. deliciosa), 65.82% (C. sinensis) and 63.46% (C. reticulata). Anti-Sclerotinia sclerotiorum activity of 90% pure limonene and at different doses (20, 50, 100, 200 and 300 L) was also investigated. This monoterpene showed to be highly active by inhibiting 100% fungus growth even at 200 and 300 L doses. This is the first report of the in vitro inhibitory effect of natural products from these three Citrus species and its results show that there is good prospect of using them experimentally to control S. sclerotiorum, in both greenhouse and field conditions.(AU)

Óleos essenciais de plantas aromáticas e medicinais geralmente exibem uma gama diversificada de atividades biológicas, pois possuem vários constituintes ativos que atuam por meio de vários mecanismos de ação. Os óleos essenciais das cascas de Citrus têm uma variedade impressionante de usos em alimentos, medicamentos entre várias outras aplicações. Os óleos essenciais (OE) de Citrus reticulata, C. sinenses e C. deliciosa foram extraídos das cascas dos frutos e analisados por CG-EM. O limoneno foi o constituinte majoritário encontrado nos óleos essenciais avaliados, nas concentrações de 98,54%, 91,65% e 91,27% para C. sinensis, C. reticulata e C. deliciosa, respectivamente. Os maiores potenciais de inibição do crescimento micelial foi observado na dose de 300 µL dos óleos. Os óleos de Citrus inibiram em 82,91% (C. deliciosa), 65,82% (C. sinensis) e 63,46% (C. reticulata) o crescimento do fungo. A atividade anti-Sclerotinia sclerotiorum do limoneno 90% puro e em diferentes doses (20, 50, 100, 200 e 300 µL) foi também investigada e este monoterpeno demonstrou-se altamente ativo inibindo 100% o crescimento do fungo inclusive nas doses de 200 e 300 µL. Este é o primeiro relato sobre o efeito inibitório in vitro dos óleos essenciais destas três espécies de Citrus e os resultados deste estudo mostram que existe uma boa perspectiva de uso destes produtos naturais experimentalmente para controlar o S. sclerotiorum tanto em condições de estufa como em condições de campo.(AU)

Expression of the citrus CsTIP2;1 gene improves tobacco plant growth, antioxidant capacity and physiological adaptation under stress conditions.

MAIN CONCLUSION: Overexpression of the citrus CsTIP2;1 improves plant growth and tolerance to salt and drought stresses by enhancing cell expansion, H 2 O 2 detoxification and stomatal conductance. Tonoplast intrinsic proteins (TIPs) are a subfamily of aquaporins, belonging to the major intrinsic protein family. In a previous study, we have shown that a citrus TIP isoform, CsTIP2;1, is highly expressed in leaves and also transcriptionally regulated in leaves and roots by salt and drought stresses and infection by 'Candidatus Liberibacter asiaticus', the causal agent of the Huanglongbing disease, suggesting its involvement in the regulation of the flow of water and nutrients required during both normal growth and stress conditions. Here, we show that the overexpression of CsTIP2;1 in transgenic tobacco increases plant growth under optimal and water- and salt-stress conditions and also significantly improves the leaf water and oxidative status, photosynthetic capacity, transpiration rate and water use efficiency of plants subjected to a progressive soil drying. These results correlated with the enhanced mesophyll cell expansion, midrib aquiferous parenchyma abundance, H2O2 detoxification and stomatal conductance observed in the transgenic plants. Taken together, our results indicate that CsTIP2;1 plays an active role in regulating the water and oxidative status required for plant growth and adaptation to stressful environmental conditions and may be potentially useful for engineering stress tolerance in citrus and other crop plants.

Continuous, high-resolution biospeckle imaging reveals a discrete zone of activity at the root apex that responds to contact with obstacles.

BACKGROUND AND AIMS: Shining a laser onto biological material produces light speckles termed biospeckles. Patterns of biospeckle activity reflect changes in cell biochemistry, developmental processes and responses to the environment. The aim of this work was to develop methods to investigate the biospeckle activity in roots and to characterize the distribution of its intensity and response to thigmostimuli. METHODS: Biospeckle activity in roots of Zea mays, and also Jatropha curcas and Citrus limonia, was imaged live and in situ using a portable laser and a digital microscope with a spatial resolution of 10 µm per pixel and the ability to capture images every 0.080 s. A procedure incorporating a Fujii algorithm, image restoration using median and Gaussian filters, image segmentation using maximum-entropy threshold methods and the extraction of features using a tracing algorithm followed by spline fitting were developed to obtain quantitative information from images of biospeckle activity. A wavelet transform algorithm was used for spectral decomposition of biospeckle activity and generalized additive models were used to attribute statistical significance to changes in patterns of biospeckle activity. KEY RESULTS: The intensity of biospeckle activity was greatest close to the root apex. Higher frequencies (3-6 Hz) contributed most to the total intensity of biospeckle activity. When a root encountered an obstacle, the intensity of biospeckle activity decreased abruptly throughout the root system. The response became attenuated with repeated thigmostimuli. CONCLUSIONS: The data suggest that at least one component of root biospeckle activity resulted from a biological process, which is located in the zone of cell division and responds to thigmostimuli. However, neither individual cell division events nor root elongation is likely to be responsible for the patterns of biospeckle activity.

Dehydrated citrus pulp digestibility and the effect of its inclusion in diet on the performance of growing rabbits / Digestibilidade da polpa cítrica desidratada e efeito de sua inclusão na dieta sobre o desempenho de coelhos em crescimento

Several experiments were conducted to determine the digestibility of dehydrated citrus pulp (DCP) and evaluate its effect on rabbit feed. Digestibility assay comprised 30 rabbits fed on two diets: a reference diet and a diet in which 20% consisted of DCP. The digestibility assay comprised 10 days for adaptation and four days for feces collection. The digestibility coefficient and digestible nutrient rates for DM, CP, NDF, ADF, and CE of DCP were respectively 83.75 and 76.04%; 70.12 and 5.03%; 40.14 and 9.52%; 68.98 and 15.09%; and 81.48% and 3394 kcalDE kg-

Conduziram-se experimentos para determinar a digestibilidade da polpa cítrica desidratada (PCD) e avaliá-la na alimentação de coelhos. Para o ensaio de digestibilidade utilizaram-se 30 coelhos recebendo duas dietas: uma referência e outra com substituição de 20% da primeira por PCD. O ensaio teve duração de dez dias para adaptação mais quatro para coleta de fezes. Os coeficientes de digestibilidade e os nutrientes digestíveis para MS, PB, FDN, FDA e EB da PCD foram respectivamente: 83,75 e 76,04%; 70,12 e 5,03%; 40,14 e 9,52%; 68,98 e 15,09%; e 81,48% e 3394 kcalED kg

Dehydrated citrus pulp digestibility and the effect of its inclusion in diet on the performance of growing rabbits / Digestibilidade da polpa cítrica desidratada e efeito de sua inclusão na dieta sobre o desempenho de coelhos em crescimento

Several experiments were conducted to determine the digestibility of dehydrated citrus pulp (DCP) and evaluate its effect on rabbit feed. Digestibility assay comprised 30 rabbits fed on two diets: a reference diet and a diet in which 20% consisted of DCP. The digestibility assay comprised 10 days for adaptation and four days for feces collection. The digestibility coefficient and digestible nutrient rates for DM, CP, NDF, ADF, and CE of DCP were respectively 83.75 and 76.04%; 70.12 and 5.03%; 40.14 and 9.52%; 68.98 and 15.09%; and 81.48% and 3394 kcalDE kg-

Conduziram-se experimentos para determinar a digestibilidade da polpa cítrica desidratada (PCD) e avaliá-la na alimentação de coelhos. Para o ensaio de digestibilidade utilizaram-se 30 coelhos recebendo duas dietas: uma referência e outra com substituição de 20% da primeira por PCD. O ensaio teve duração de dez dias para adaptação mais quatro para coleta de fezes. Os coeficientes de digestibilidade e os nutrientes digestíveis para MS, PB, FDN, FDA e EB da PCD foram respectivamente: 83,75 e 76,04%; 70,12 e 5,03%; 40,14 e 9,52%; 68,98 e 15,09%; e 81,48% e 3394 kcalED kg <->1 MS. Para o desempenho utilizaram-se 120 coelhos recebendo dietas com diferentes níveis de PCD (0, 20, 40, 60, 80 e 100%) substituindo o milho. Observou-se redução linear (p < 0,01) para o consumo de ração e ganho de peso diário, peso vivo aos 50 e 70 dias e rendimento de carcaça com o aumento gradativo de PCD. Efeitos quadráticos (p < 0,01) sobre a conversão alimentar dos 32 aos 50 e 32 aos 70 dias de idade provocaram melhores valores com 42,74 e 44,40% de PCD, respectivamente. PCD a 20% não afetou (p > 0,05) nenhuma característica de desempenho quando comparada à dieta controle. Conclui-se: a PCD pode substituir o milho até 20% nas dietas de coelhos.(AU)

The Xanthomonas citri effector protein PthA interacts with citrus proteins involved in nuclear transport, protein folding and ubiquitination associated with DNA repair.

Xanthomonas axonopodis pv. citri utilizes the type III effector protein PthA to modulate host transcription to promote citrus canker. PthA proteins belong to the AvrBs3/PthA family and carry a domain comprising tandem repeats of 34 amino acids that mediates protein-protein and protein-DNA interactions. We show here that variants of PthAs from a single bacterial strain localize to the nucleus of plant cells and form homo- and heterodimers through the association of their repeat regions. We hypothesize that the PthA variants might also interact with distinct host targets. Here, in addition to the interaction with alpha-importin, known to mediate the nuclear import of AvrBs3, we describe new interactions of PthAs with citrus proteins involved in protein folding and K63-linked ubiquitination. PthAs 2 and 3 preferentially interact with a citrus cyclophilin (Cyp) and with TDX, a tetratricopeptide domain-containing thioredoxin. In addition, PthAs 2 and 3, but not 1 and 4, interact with the ubiquitin-conjugating enzyme complex formed by Ubc13 and ubiquitin-conjugating enzyme variant (Uev), required for K63-linked ubiquitination and DNA repair. We show that Cyp, TDX and Uev interact with each other, and that Cyp and Uev localize to the nucleus of plant cells. Furthermore, the citrus Ubc13 and Uev proteins complement the DNA repair phenotype of the yeast Deltaubc13 and Deltamms2/uev1a mutants, strongly indicating that they are also involved in K63-linked ubiquitination and DNA repair. Notably, PthA 2 affects the growth of yeast cells in the presence of a DNA damage agent, suggesting that it inhibits K63-linked ubiquitination required for DNA repair.

Characterization of mandarin (citrus spp): using morphological and afpl markers

Se evaluaron 63 cultivares de mandarina (Citrus spp.) provenientes de la colección del Campo Citrícola Experimental Francisco Villa, Tamaulipas, México, usando marcadores morfológicos y AFLP (Amplified Fragment Length Polymorphism). Se usaron 20 caracteres cuantitativos y 10 cualitativos de hojas, flores y frutos. Las mejores combinaciones de iniciadores AFLP fueron la Mse +CAG más Eco +ACA, y Mse +CAA más Eco +AGG, dando un total de 109 bandas con un 86 por ciento de polimorfismo. Tanto los marcadores morfológicos como los moleculares mostraron un alto grado de variación entre los individuos analizados, lo que indica una importante fuente de diversidad genética que puede ser utilizada en futuros programas de mejoramiento genético. Aunque la comparación de los datos morfológicos y moleculares usando la prueba de Mantel no mostró una correlación significativa (r= 0.31), ambas técnicas parecen ser complementarias para la caracterización de mandarinas

Participation of the mitochondrial permeability transition pore in nitric oxide-induced plant cell death.

In the present study, we investigated the involvement of the mitochondrial permeability transition pore (PTP) in nitric oxide (NO)-induced plant cell death. NO donors such as sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine inhibited growth and caused death in suspension-cultured cells of Citrus sinensis. Cells treated with SNP showed chromatin condensation and fragmentation, characteristic of apoptosis. SNP caused loss of the mitochondrial membrane electrical potential, which was prevented by cyclosporin A (CsA), a specific inhibitor of PTP formation. CsA also prevented the nuclear apoptosis and subsequent Citrus cell death induced by NO. These findings indicate that mitochondrial PTP formation is involved in the signaling pathway by which NO induces apoptosis in cultured Citrus cells.

Cellular automata model for citrus variegated chlorosis.

A cellular automata model is proposed to analyze the progress of citrus variegated chlorosis epidemics in São Paulo orange plantations. In this model epidemiological and environmental features, such as motility of sharpshooter vectors that perform Lévy flights, level of plant hydric and nutritional stress, and seasonal climatic effects, are included. The observed epidemic data were quantitatively reproduced by the proposed model on varying the parameters controlling vector motility, plant stress, and initial population of diseased plants.