Feijoa Research Articles

MORPHOLOGICAL AND ANATOMICAL RESEARCH OF LEAVES OF FEIJOA SELLOWIANA BERG

Feijoa leaves gathered from Feijoa sellowiana Berg. of Myrtaceae family on the Black Sea coast of the Caucasus were the object of this research. Establishment of morphological and anatomical features for diagnosis of feijoa leaves was the purpose of this work. Using macro- and microscopic analysis methods we have determined external and microdiagnostic features which can be used for development of authenticity of the feijoa leaves active parts.

Development and quality of pineapple guava fruit in two locations with different altitudes in Cundinamarca, Colombia

Fruit growth is stimulated by different weather conditions. The aim of this study was to determine the influence of weather conditions on the physicochemical properties of pineapple guava fruit growth. Twenty trees were marked in two production areas located at different altitudes (1,800 and 2,580 m.a.s.l.), and measurements were performed every 7 days from 99 and 141 days post-anthesis to harvest at altitudes of 1,800 and 2,580 m.a.s.l., respectively. The results indicate that altitude and weather conditions greatly influence the growth and development of pineapple guava fruit, and these effects are primarily manifested in the physical characteristics of the fruit. The weight and size of the fruit at harvest are directly related to the altitude of the production area. The weather condition that has the greatest impact on total titratable acidity at harvest is cumulative radiation during fruit growth; the highest value of total soluble solids at harvest corresponds to the location with the higher altitude, lower rainfall and relative humidity and higher cumulative radiation during the fruit growth period. The hue angle and pulp firmness at harvest are not influenced by the location or weather conditions at any location and do not determine the fruit quality at harvest time.

Agronomic, nutraceutical and molecular variability of feijoa (Acca sellowiana (O. Berg) Burret) germplasm

During three years of investigations (2011–2013), 12 feijoa (Acca sellowiana (O. Berg) Burret) cultivars fruits were characterised in terms of genetic, physico-chemical, nutraceutical and sensory properties. The physical-chemical, nutritional and sensory features were also correlated with a sequence-related amplified polymorphism (SRAP) analysis to assess the existence of a possible genetic relationships among the 12 cultivars and quality traits. SRAP analysis revealed genetic diversity among the 12 feijoa cultivars, this finding have been confirmed by the pomological, nutraceutical and sensory traits. A high antioxidant activity and a considerable amount of bioactive compounds, especially phenols, flavonoids and ascorbic acid, were detected. A higher level of phenols was detected in Triumph (251±25.9mg GAE/100g FW) and Smith (226.6±9.53mg GAE/100g FW), the latter of which was also richer in ascorbic acid (42.9±0.63mg AA 100g−1FW) and flavonoids (40±0.88mg CTE 100g−1 FW) compared to the remaining cultivars. Cluster analyses and principal component analysis made it possible to establish similarities among the cultivars depending on their quality and sensorial characteristics.The Mantel's correlation coefficient of SRAP marker and morphological-qualitative-sensorial traits was 0.495 reflecting that the SRAP marker-based clustering of feijoa cultivars showed similarity to the dendrogram topologies of the morphological-qualitative-sensorial trait-based clustering, although there were some differences in the positioning of some feijoa cultivars in the clusters. This study indicated that the combination of both SRAP marker and morphological trait analysis is more informative for a refined identification and characterisation of plant varieties.

Ecophysiological aspects of feijoa (Acca sellowiana Berg) under irrigation and hydric defficiency

El trabajo se realizo en el municipio de Firavitoba - Boyaca, con el objeto de evaluar las respuestas de crecimiento y de desarrollo de Acca sellowiana en condiciones de riego y de sequia. Se utilizaron plantas cultivar Tibasosa, de tres anos de edad, en buenas condiciones fitosanitarias y con similar tamano. El riego, se aplico por goteo, con goteros de 4L h -1 y 2 goteros/planta. Se aplico un diseno de bloques completos al azar, con tres bloques y 10 plantas por parcela. Dentro de cada bloque, se distribuyeron al azar cinco tratamientos correspondientes a diferentes niveles de riego: 100% (testigo), 75, 50, 25 y 0%. Por cada planta, de manera directa, se contaron en cuatro ocasiones hasta el dia 406, despues de iniciar los tratamientos, el numero de ramas, de hojas completamente formadas y de botones florales desarrollados. La altura, se midio desde el cuello de la raiz hasta la parte mas alta de la planta; el area foliar (cm 2 ), se determino con un medidor portatil de area foliar; el indice de area foliar (IAF), se calculo mediante la relacion entre el area foliar y el area de suelo ocupado por la planta. Los datos obtenidos fueron sometidos a un analisis de varianza (ANAVA) y a la prueba de comparacion de promedios de Tukey (5%). El software utilizado fue SAS Ve. 9.2. Se determino que el riego es fundamental para un buen desarrollo fisiologico de la feijoa, especificamente, para el desarrollo vegetativo de la planta, en especial, con factores de agotamiento entre el 50 y 75%.

A Introdução e os Usos da Feijoa ou Goiabeira Serrana (Acca sellowiana): A perspectiva da história ambiental

A feijoa (Acca sellowiana), também conhecida como goiabeira-serrana, é uma espécie frutífera nativa do planalto meridional brasileiro e do norte do Uruguai. No Brasil, a espécie se encontra principalmente nos biomas Pampa e Mata Atlântica, neste último parte da fitofisionomia da Floresta Ombrófila Mista. A espécie foi introduzida em outros países, fora da sua área natural de ocorrência. O objetivo deste trabalho é analisar o processo de introdução e do uso da feijoa fora e dentro da sua área de ocorrência natural. Faz parte da História Ambiental estudar as relações dos homens e mulheres com o meio ambiente; desta forma, o estudo da domesticação da feijoa se insere neste contexto. Mesmo o Brasil sendo a principal área de ocorrência natural da feijoa, ainda é importador das frutas produzidas na Colômbia – maior país exportador da espécie. No Brasil, a feijoa tem se destacado ainda recentemente em termos de pesquisa e uso. A fruta, já bastante conhecida e utilizada no exterior, vem ganhando espaço no cenário nacional, possibilitando a manutenção de uma espécie nativa e auxiliando na conservação da floresta a qual ela pertence.Palavras-Chave: Feijoa; Domesticação de Plantas; Usos dos Recursos Naturais.

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Guayabo del país o goiaba serrana [Acca sellowiana (Berg.) Burret] es uno de los recursos fitogenéticos subutilizados más valiosos de Uruguay y Brasil. Este árbol de fruto comestible, es endémico de una estrecha región sudamericana que abarca el noreste uruguayo y sur de Brasil, donde su cultivo se limita al uso doméstico o a pequeños huertos comerciales. El uso de los materiales de la especie se ve limitado por el desconocimiento de la diversidad presente tanto en poblaciones naturales como en materiales cultivados. El objetivo de este trabajo fue la elaboración de una lista de descriptores que permita la caracterización y evaluación de los materiales para la conservación, uso sostenible e incorporación de diversidad en los programas de mejoramiento genético. Se elaboró una lista preliminar de 41 descriptores morfo-fenológicos de hoja, flor y fruto, que se aplicó in situ a 204 individuos pertenecientes a cuatro poblaciones silvestres del noreste del Uruguay. Con el método de Máxima Verosimilitud Restringida se estimaron los componentes de la varianza entre poblaciones (s²P), entre individuos dentro de poblaciones (s²I(P)), entre muestras dentro de individuo (s²M(IP)) y sus intervalos de confianza utilizando un Modelo Lineal Mixto. Para la determinación del poder discriminante de las variables cuantitativas se adoptó como criterio estadístico la comparación de IC (límite inferior ICs²I(P)>límite superior ICs²M(IP)) y se calculó la razón entre s²I(P)/s²M(IP). Para las variables cualitativas se calculó el estadístico F para la determinación de las diferencias significativas entre individuos con el objetivo de identificar descriptores discriminantes de individuos. También se determinaron las variables que discriminan poblaciones. Se validaron siete descriptores cualitativos (forma de fruto, posición de los sépalos, color de pulpa, color interno de la cáscara, dureza de cáscara, clases de distancia estigma-estambres) y ocho descriptores cuantitativos (altura, diámetro y peso de fruto, peso de pulpa, espesor y resistencia de cáscara, distancia estigma-estambres y número de estambres) para diferenciar individuos. Se encontraron 16 variables cuantitativas y 10 cualitativas discriminantes de las poblaciones estudiadas.

DNA methylation patterns and karyotype analysis of off-type and normal phenotype somatic embryos of feijoa

Acca sellowiana is a native species to the southern region of Brazil, with secondary dispersion in Uruguay northeast. The potentially economic interest of this species motivated many fundamental and applied researches, such as micropropagation protocols development, including somatic embryogenesis (SE). Previous studies have reported the high frequency of off-type somatic embryos in A. sellowiana SE and low conversion efficiency, possibly due to this high off-type somatic embryos formation. In this sense, this study was aimed to evaluate the effect of 2,4-dichlorophenoxyacetic acid (2,4-D) in the induction and development of somatic embryos in direct and indirect SE through cytogenetic and DNA methylation analysis. The results of the present work reinforces the previous findings that 2,4-D plays a key role in the SE induction in A. sellowiana. However, the continuous presence of this auxin in the culture medium enhances the rate of off-type somatic embryos. This auxin also apparently affects the cells and chromosomes size in normal and off-type somatic embryos and DNA methylation patterns of the analyzed samples. These findings may indicate that the off-type somatic embryos formation may be related to genetic and/or epigenetic changes caused by long-term cultivation in A. sellowiana. The intermediate phase of callus also indicated increased formation of off-types, corroborating other studies that showed that indirect SE could cause increased formation of anomalies in regenerated plantlets.

Optimisation of the process parameters of combined high hydrostatic pressure and dense phase carbon dioxide on enzyme inactivation in feijoa (Acca sellowiana) puree using response surface methodology

Abstract The effects of pressure (200–600 MPa), process time (1–13 min), pH (3.0–3.6), and CO2 levels (no CO2, CO2 saturation, and saturation with addition of 8.5 mL CO2/g sample) in a combined high hydrostatic pressure (HHP) and dense-phase carbon-dioxide process on 3 enzymes: peroxidase (POD), polyphenoloxidase (PPO) and pectinmethylesterase (PME), of feijoa (Acca sellowiana) puree were studied using response surface methodology (27 treatments). Increasing treatment time reduced all enzyme activities, while increasing CO2 levels decreased PME activity, and pressure influenced PPO activity. The lower pH values tended to increase enzyme inactivation. The optimal process conditions of 13 min, 600 MPa, pH = 3, CO2 saturation, resulted in 74.3 ± 3.3%, 70.9 ± 2.6% and 53.9 ± 0.9% residual activity for POD, PPO and PME respectively. Combination of CO2 with HHP induced synergistic enzyme inactivation, and reduction of pH did not prove to be the main factor. Industrial relevance High hydrostatic pressure (HHP) achieves the safety of beverages as a non-thermal method, but it may activate undesirable enzymes. Therefore, the product may have a short shelf life due to e.g. settling and colour change. Addition of carbon dioxide to HHP was shown to increase enzyme inactivation. Our study determined the optimal conditions to reduce enzyme activity in feijoa puree by this method. When industrial means become available to combine these processes, then in addition to safety and nutrient preservation, the shelf life of products will also increase.

THERMAL TIME FOR REPRODUCTIVE PHENOLOGICAL STAGES OF PINEAPPLE GUAVA (Acca sellowiana (O. Berg) Burret)

Crop development of feijoa ( Acca sellowiana (O. Berg) Burret) is mainly stimulated by temperature, but is also affected by other climatic factors. The determination of the development in terms of thermal time or growing degree days (GDD) is more precise than calendar days. The aim of this study was to propose a phenological model for feijoa cv. Quimba, in which the base temperature (Tb) for four different phenological stages and its duration in terms of GDD is estimated to predict the timing of anthesis, fruit setting and harvesting. During the years 2012 to 2014, in two localities of the department of Cundinamarca, Colombia, twenty trees per farm were labeled, dates of occurrence of phenological stages, starting from floral button were recorded. Tb was estimated using the method of minimum coefficient of variation, as well as duration of the four reproductive phenological stages in terms of GDD. The results showed that Tb and GDD vary depending on the stage of development of the crop; in general, an average of 2651 GDD and 189 days is required to reach the flower bud to the fruit harvest. The parameters of the regression analysis showed that the model successfully predicted phenological stages when estimated Tb for each of them was used, with high determination coefficient. Cross-validation showed good statistical fit between predicted and observed values; intercept was not significantly different from zero (p <0.05) and the slope was statistically equal to one TIEMPO TERMICO PARA ESTADOS FENOLOGICOS REPRODUCTIVOS DE LA FEIJOA ( Acca sellowiana (O. Berg) Burret) El desarrollo del cultivo de feijoa ( Acca sellowiana (O. Berg) Burret) es principalmente estimulado por la temperatura, pero tambien es afectado por otros factores climaticos. La determinacion del desarrollo en terminos de tiempo termico o grados dia de crecimiento (GDC) es mas precisa que en dias calendario. El objetivo de este estudio fue proponer un modelo fenologico para la feijoa cv. Quimba, en el que se estima la temperatura base (Tb) para cuatro periodos fenologicos reproductivos diferentes y su duracion en terminos de GDC, para predecir las fechas de antesis, cuaje de fruto y cosecha. Se marcaron veinte arboles por finca en dos localidades del departamento de Cundinamarca, Colombia, durante los anos 2012 a 2014, se registraron las fechas de aparicion de los estados fenologicos, desde la formacion del boton floral. Se estimo Tb usando el metodo de minimo coeficiente de variacion, asi como la duracion de los cuatro estados fenologicos reproductivos en terminos de GDC. Los resultados mostraron que Tb y GDC varian dependiendo de la etapa de desarrollo del cultivo; en general, se requiere una media de 2651 GDC y 189 dias para llegar de boton floral a la cosecha del fruto. Los parametros del analisis de regresion mostraron que el modelo predijo satisfactoriamente las etapas fenologicas cuando se uso la Tb estimada para cada una de ellas, con alto coeficiente de determinacion. La validacion cruzada mostro buen ajuste estadistico entre valores pronosticados y observados; la intercepcion no fue significativamente diferente de cero (p <0,05) y la pendiente fue estadisticamente igual a uno.

Relationship between stomatal density, transpiration and environmental conditions in pineapple guava (Acca sellowiana [O. Berg] Burret)

Pineapple guava is a plant with a high adaptation to environmental conditions of the Andean region. Although there exists an increased national and international demand, there are many physiological aspects that still need to be known. This study aimed to evaluate the transpiration rate, the density of stomata, and the associated environmental factors in the upper and lower stratum of the tree crown of the pineapple guava crop in Tibana municipality (Boyaca, Colombia), under open air conditions. Measurements were made of leaf temperature, transpiration rate, irradiance and relative humidity (RH) in two strata during 7 daily hours (8:00, 9:00, 10:00, 11:00, 12:00, 13:00 and 14:00 h). The upper stratum showed a higher transpiration rate and a major average number of stomata, 91/mm2 vs. 78/mm2 in the lower stratum. Leaf transpiration increased directly with increasing temperature (more in the upper stratum than in the lower stratum) and with the irradiance; while transpiration increased as the relative humidity decreased.

Spatial Patterns and Associations ofAnastrepha fraterculus(Diptera: Tephritidae) and Its ParasitoidDoryctobracon areolatus(Hymenoptera: Braconidae) in Organic Orchards ofPsidium guajavaandAcca sellowiana

The objective of this study was to determine the spatial patterns and associations of the South American fruit fly (Anastrepha fraterculus (Wiedemann); Diptera: Tephritidae) and its parasitoids in organic orchards of common guava and pineapple guava. The field study was conducted from Feb to Mar 2010 in 2 organically-managed orchards, one of common guava (Psidium guajava L.) (Myrtaceae) and the other of pineapple guava [Acca sellowiana (O. Berg) Burret] (Myrtaceae), in Rio Grande do Sul (RS) state, Brazil. Fruits were sampled from all trees at 2 sampling occasions, spaced 15 days apart, just before fruits were in the final maturation period. On each tree, 10 fruits were randomly collected from the entire canopy and held in the laboratory until the flies had pupated. Heterogeneity of insect count data was analyzed by fitting theoretical distributions to the data and calculating dispersion indices. The spatial arrangement was evaluated with SADIE. Local spatial associations were measured using a SADIE association index (I t a). In a common guava orchard the emerged individuals were A. fraterculus, and its parasitoid, Doryctobracon areolatus (Szépligeti) (Par) (Hymenoptera: Braconidae) with a parasitism rate of 8.3%. The same 2 species occurred in a pineapple guava orchard, where the parasitism rate was 25.5%. The variances of the data for both the A. fraterculus and D. areolatus were greater than the corresponding means for most cases, hence the significance of both the dispersion index (I) and the values of k of the negative binomial suggested an aggregated distribution pattern. On the other hand, the clustering indices (v i. and v j ) and I t a suggested a random spatial pattern of A. fraterculus and the parasitoid for most situations (orchards and sampling times). Spatial association indices revealed significant associations for 5 of the 12 pair-wise comparisons, 3 in the common guava orchard and 2 in the pineapple guava orchard.

Characterization of 10 new nuclear microsatellite markers in Acca sellowiana (Myrtaceae).

• Premise of the study: Microsatellite primers were identified and characterized in Acca sellowiana in order to expand the limited number of pre-existing polymorphic markers for use in population genetic studies for conservation, phylogeography, breeding, and domestication.• Methods and Results: A total of 10 polymorphic microsatellite primers were designed from clones obtained from a simple sequence repeat (SSR)–enriched genomic library. The primers amplified di- and trinucleotide repeats with four to 27 alleles per locus. In all tested populations, the observed heterozygosity ranged from 0.269 to 1.0.• Conclusions: These new polymorphic SSR markers will allow future genetic studies to be denser, either for genetic structure characterization of natural populations or for studies involving genetic breeding and domestication process in A. sellowiana.

A first genetic map of Acca sellowiana based on ISSR, AFLP and SSR markers

A first integrated linkage map of Acca sellowiana (Berg.) Burret (2n=2x=22), commonly known as ‘pineapple guava’ was constructed using a 160 (TCO×BR) full-sib F1 progeny based on intersimple sequence repeat (ISSR), amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. To develop an integrated map, we used a novel statistical approach that provided a simultaneous estimation of linkage and linkage phases based on maximum-likelihood analysis. The integrated map comprised 219 (27 ISSRs and 192 AFLPs) linked markers that were assigned to 10 major linkage groups (LG) representing a total map length of 2875cM and average distance between markers of 13.8cM. TCO (14 LG, 83 markers, 1264.6cM) and BR (18 LG, 94 markers, 1295.1cM) parent maps were also constructed through the same statistical approach but using only appropriate pseudo-testcross configuration markers. All the LG of the integrated map shared markers with either TCO or, BR or both parental maps. The integrated map provides a framework for further genetic and genomic analyses in A. sellowiana.

Phytochemical composition and gastroprotective effect of Feijoa sellowiana Berg fruits from Sicily

Objective: To assess the fruit of Feijoa sellowiana Berg var. coolidge and gorgiona, cultured in Sicily, for its gastroprotective effect, in association with performing phytochemical evaluation. Methods: By means of HPLC, vitamin E complex and polyphenol compounds were determined. The gastroprotective effect was investigated on ethanol-induced ulcers in rats, with sucralfate as reference drug. Samples of gastric mucosae, stained by periodic acid-Shiff and haematoxylin/ eosin, were observed by light microscopy. Results: In pulp and peel samples of both varieties of fruit α, β and γ tocopherols were identified, while δ was only in var. coolidge. In whole fruit of two varieties, catechin, eriodictyol, eriocitrin, pyrocatechol, quercetin, rutin, ellagic, gallic and syringic acid were determined. The fruit showed gastroprotective effect (ulcer index: var. coolidge=1.07, var. gorgiona=1.02). The efficacy was comparable to that of sucralfate (ulcer index 1.10). Histological examination confirmed the inhibition of ulcerogenic activity of the ethanol. Conclusions: Active principles of Feijoa sellowiana can play an important role in human diet and show beneficial effects on various diseases, particularly those caused by oxidative processes resulting in cell damage. The amount of polyphenols and vitamin E complex confirms the nutritional value of this fruit, grown in pedoclimatic condition very different from the origin area.

Feijoa sellowianaBerg Fruit Juice: Anti-Inflammatory Effect and Activity on Superoxide Anion Generation

Feijoa sellowiana Berg var. coolidge fruit juice was studied in vivo for the anti-inflammatory activity by carrageenin-induced paw edema test and in vitro for the effects on superoxide anion release from neutrophils in human whole blood. The fruit juice was analyzed by the high-performance liquid chromatography method, and quercetin, ellagic acid, catechin, rutin, eriodictyol, gallic acid, pyrocatechol, syringic acid, and eriocitrin were identified. The results showed a significant anti-inflammatory activity of F. sellowiana fruit juice, sustained also by an effective antioxidant activity observed in preliminary studies on 1,1-diphenyl-2-picrylhydrazyl (DPPH) test. In particular, the anti-inflammatory activity edema inhibition is significant since the first hour (44.11%) and persists until the fifth hour (44.12%) of the treatment. The effect on superoxide anion release was studied in human whole blood, in the presence of activators affecting neutrophils by different mechanisms. The juice showed an inhibiting response on neutrophils basal activity in all experimental conditions. In stimulated neutrophils, the higher inhibition of superoxide anion generation was observed at concentration of 10(-4) and 10(-2) mg/mL in whole blood stimulate with phorbol-myristate-13-acetate (PMA; 20% and 40%) and with N-formyl-methionyl-leucyl-phenylalanine (FMLP; 15% and 48%). The significant reduction of edema and the inhibition of O2(-) production, occurring mainly through interaction with protein-kinase C pathway, confirm the anti-inflammatory effect of F. sellowiana fruit juice.

Correlation between Sun Protection Factor and Antioxidant Activity, Phenol and Flavonoid Contents of some Medicinal Plants.

Long exposure of UV radiation increases risk of skin diseases such as cancer and photoallergic reactions. UV-B (280-320 nm) radiation is mainly responsible for inducing the skin problems. Skin protection is a suitable method against ultraviolet radiation-induced damage. Various synthetic agents have been used as photo protective but because of their potential toxicity in humans, they have limited usage. Natural substances have been recently considered as potential sunscreen resources due to their absorption in the UV region and their antioxidant activity. In the present study, the UV protective effects of 20 extracts from four common medicinal plants were evaluated. Their phenol and flavonoid contents and antioxidant activities were determined and correlation between SPF and these contents were evaluated. SPFs were between 0.102 and 24.470. The highest value was reached with ultrasonic extract of Crataegus pentagyna (SPF = 24.47) followed by methanolic extract of Feijoa sellowiana (SPF = 1.30). Good correlation was found between SPF and phenolic contents (Correlation Coefficient = 0.55 and p = 0.01) but no correlations were found between SPF and flavonoid contents or antioxidant activity. These extracts can be used alone or as additives in other sun screen formulations to enhance their SPF.

Nephroprotective effects of Feijoa Sellowiana leaves extract on renal injury induced by acute dose of ecstasy (MDMA) in mice.

Because of the high total phenolic contents of Feijoa sellowiana, its nephroprotective effect was determined in 3,4-methylene dioxymethamphetamine (MDMA) treated mice. Animals received 10, 20 and 40 mg/kg doses of aqueous or methanol extract of F. sellowiana leaves, intra-peritoneally. After one hour, an acute administration of MDMA (20 mg/kg, IP) was injected. Nephroprotective effect was assayed by determination of serum creatinine, serum urea and kidney glutathione level. Histopathological study was also used. Results : Both extracts at 40 mg/kg resulted in a significant reversal in the raised serum creatinine levels (P <0.05). Not statistically significant was observed in effect of two extracts (P>0.05). A decrease in urea/ creatinine ratio was observed following aqueous extract treatment. Methanolic extract showed higher activity in increasing kidney glutathione (P<0.001 compared to MDMA group). Methanol extract showed higher protective activity in histopathology study. F. sellowiana extract resulted in a markedly decrease in the nephrotoxicity of MDMA in mice.

Avaliação da morfologia interna de sementes de Acca sellowiana O. Berg por meio de análise de imagens

Acca sellowiana O. (Berg) Burret é uma fruteira nativa da região Sul do Brasil e do Uruguai, que apresenta grande potencial de uso na recuperação de áreas degradadas. O objetivo deste trabalho foi avaliar a morfologia interna de sementes de Acca sellowiana O. Berg por meio da análise de imagens de raios X e relacionar os resultados com a germinação das sementes. Sementes de Acca sellowiana O. Berg, representadas por três lotes, foram analisadas pelo teste de raios X e, posteriormente, conduzidas ao teste de germinação, com avaliação aos 44 dias após a semeadura. As imagens de raios X foram analisadas com o software ImageJ. A análise das imagens radiográficas de sementes de Acca sellowiana permite a mensuração das áreas internas livres, assim como a determinação da relação entre estas e a germinação. Danos internos detectados por meio de raios X afetam a germinação das sementes.

Resistant accessions of wild Psidium spp. to Meloidogyne enterolobii and histological characterization of resistance

Meloidogyne enterolobii has been reported in some states of Brazil and other countries causing severe damage on commercial guava (Psidium guajava). The use of resistant varieties is the most effective way to manage nematode parasitism. This study screened 51 accessions of Psidium spp. selected from the Psidium Germplasm Collection (Embrapa) to look for resistance against M. enterolobii. Six months after inoculation, nematode reproduction factor (RF) was used to assess resistance. The following species were resistant to M. enterolobii: P. cattleianum (yellow guava), P. friedrichsthalianum (Costa Rican guava), Acca sellowiana (feijoa) and P. rufum (purple guava). All 43 wild accessions of P. guajava were susceptible, as well as three accessions of P. guineense (Brazilian guava), one of P. acutangulum (pear guava) and the susceptible control P. guajava cv. Paluma. When used as rootstocks under greenhouse conditions, P. cattleianum and P. friedrichsthalianum were compatible with cv. Paluma; however, in greenhouse and field conditions only 50% of both scions survived. No apparent hypersensitive response (HR) was seen in the resistant guava P. cattleianum and P. friedrichsthalianum. Juveniles were able to develop normal feeding sites similar to those in susceptible roots 6–13 days after inoculation (dai). From 27 to 32 dai, giant cell deterioration was observed and nematodes showed arrested development. The majority of nematodes failed to reach maturity and did not begin laying eggs in resistant roots. These results suggested that the induction of resistance is relatively late in this pathosystem.

Dynamics of physiological and biochemical changes during somatic embryogenesis of Acca sellowiana

Feijoa (Acca sellowiana [O. Berg] Burret [Myrtaceae]) is a native fruit species of southern Brazil and northern Uruguay. This species is amenable to somatic embryogenesis and therefore suitable as a model system for comparative studies of zygotic and somatic embryo development. In seed plants, embryogenesis involves three main steps, which are regulated by many factors, such as hormones, proteins, polyamines, and transcription factors. In the present work, the dynamics of protein, sugar, starch, amino acid, and polyamine accumulation were assayed during somatic embryogenesis of A. sellowiana. Protein, starch, amino acid, and polyamine levels accumulated unevenly during the induction phase of somatic embryogenesis, while the sugar content remained stable. Throughout the different developmental stages of somatic embryogenesis, synthesis and accumulation of proteins and amino acids showed patterns similar to those reported previously during the development of zygotic embryos of this same species. Differential patterns of polyamine accumulation were observed. This is important because these compounds affect the synthesis of other endogenous growth regulators, such as auxinindole-3-acetic acid that is mainly involved in the establishment of embryo polarity. Taken together, the present work brings new insights to the physiological and biochemical dynamics that occur during somatic embryogenesis of A. sellowiana.