Rodrigo Infante

Development and characterization of microsatellite markers in pomegranate (Punica granatum L.)

The pomegranate (Punica granatum L.) is a temperate climate species requiring high temperatures for proper and complete ripening. The species is consumed as a fresh fruit, but also can be used to obtain transformed products such as juice, jam, or preserve. It is a fruit tree species with a high degree of diversity, but the identification of cultivars by morphological traits is very difficult. Thus, the characterization of genotypes through molecular markers is of great value for germplasm preservation, genetic studies, and plant breeding. The number of simple sequence repeat (SSR or microsatellite) markers developed for this genus is too low, so in this work we report the development of 117 microsatellite loci from a CT/AG-enriched pomegranate genomic library. In order to check their utility, eleven accessions were analyzed. The polymorphism information content (PIC) value across all loci ranged between 0.09 and 0.71, with an average of 0.37. These markers will facilitate genetic diversity studies, mapping, and genotyping of pomegranate.

Domestication of the Chilean guava (Ugni molinae Turcz.), a forest understorey shrub, must consider light intensity

A Chilean guava ecotype (Ugni molinae Turcz.) was cultivated in Santiago during the summer of 1999/2000 in order to assess the effect of shading on photosynthesis. Plants were grown under either 50% shading or full sunlight and chlorophyll fluorescence, net assimilation rates of CO2, photosynthetic pigment contents, were measured 2 months after planting, in each light regime, during the day. The capacity to recover the photochemical efficiency of photosystem II in light grown plants, measured as Fv/Fm after 30 min dark adaptation was markedly reduced, reaching values lower than 0.5 at midday, with a sunlight PPFD of 1600 mmol m � 2 s � 1 . On the other hand, the shaded plants showed a nearly complete recovery of the parameter. The photochemical quenching of chlorophyll fluorescence, reached a value of 0.47, also at midday, in full light grown plants, nearly half that observed in the shade, indicating a high PSII excitation pressure in the former. The light saturated net CO2 assimilation rates, measured in controlled conditions of temperature, were markedly lower in the full light plants compared to the shade ones. It is concluded that the Chilean guava is not able to cope with the light intensities characteristic of many Mediterranean climates, resulting in chronic photoinhibition.

Effect of harvest maturity stage on the sensory quality of 'Palsteyn' apricot (Prunus armeniaca L.) after cold storage

Summary Fresh apricots (Prunus armeniaca L.) are in high demand, but are available for only a short period during the Spring and the beginning of the Summer. There is no information on the correct harvest maturity stage that should be chosen to ensure a long post-harvest life and high sensory quality. The objective of this study was to evaluate the effect of maturity stage at harvest on the sensory quality of ‘Palsteyn’ apricots after 14, 28, or 42 d in cold storage. Sourness, flavour, and acceptability showed major changes during cold storage. Ripe fruit (orange-yellow skin colour) showed the highest acceptability, as assessed by a “mini-consumer test” (i.e., an untrained panel; n = 36). Fruit harvested at an intermediate stage of maturity (light yellow skin colour) reached an average acceptability, while unripe fruit (greenish skin colour) were not acceptable. After 28 d of cold storage, fruits were still acceptable; but, after 42 d, fruits reached the “dislike” zone. On a principal component analysis, acceptability was shown to be positively associated with sweetness, flavour, juiciness, and aroma, and negatively associated with sourness. After 28 d and 42 d of cold storage, unripe fruit appeared to have low acceptability and quality attributes. ‘Palsteyn’ apricot harvested with an orange-yellow skin colour, as the least ripe fruits, showed that they could reach high sensory quality standards and were able to withstand long periods of cold storage.

Postharvest Sensory and Phenolic Characterization of ’Elegant Lady’ and ’Carson’ Peaches

La demanda de fruta de alta calidad se ha incrementado junto con la necesidad de asegurar este atributo a los consumidores. En este sentido, el objetivo de este estudio fue caracterizar durazno (Prunus persica (L.) Batsch) de variedades de pulpa fundente (‘Elegant Lady’) y no fundente (‘Carson’), considerando su contribucion de compuestos bioactivos y su calidad sensorial en fruta madura a cosecha y luego de un periodo prolongado de almacenamiento refrigerado. Las variedades fueron evaluadas a la cosecha (F0) y luego de 30 d de almacenamiento refrigerado (F30), ademas de un periodo de maduracion a 20 oC en F0 y F30 (R0 y R30, respectivamente). Se registro el peso del fruto, firmeza de pulpa, contenido de solidos solubles (CSS), acidez titulable (TA), y color de fondo (Hue) en cada tratamiento. Ademas se cuantificaron los fenoles totales y se realizo una caracterizacion fenolica de ambas variedades a traves de un HPLC (High-Performance Liquid Chromatography) para detectar los principales compuestos fenolicos de bajo peso molecular presentes en el fruto. Finalmente un panel entrenado evaluo los principales parametros sensoriales en R0 y R30. El contenido de fenoles totales no vario significativamente como resultado del almacenamiento en frio, las diferencias observadas solo fueron atribuibles a los genotipos. Se detectaron 15 y 12 compuestos fenolicos de bajo peso molecular en ‘Elegant Lady’ y ‘Carson’, respectivamente, siendo catequina el principal compuesto encontrado en ambos cultivares, aunque en mayores concentraciones en ‘Elegant Lady’. En la caracterizacion fenolica, ‘Elegant Lady’ aparecio mas estrechamente relacionada con los flavonoides que ‘Carson’. Despues de 30 d de almacenamiento en frio, ‘Elegant Lady’ no fue aceptable para consumo debido a la aparicion de desordenes fisiologicos como harinosidad, mientras que ‘Carson’ mostro una puntuacion promedio dentro del rango de aceptabilidad.

Determination of harvest maturity of D'Agen plums using the chlorophyll absorbance index

R. Infante, P. Rubio, L. Contador, M. Noferini, and G. Costa. 2011. Determination of harvest maturity of D’Agen plums using the chlorophyll absorbance index. Cien. Inv. Agr. 38(2): 199-203. The objective determination of the optimal harvest date for plums intended either for industrial processing or for consumption as fresh fruit is a fundamental concern of the fruit industry. A portable visible/near infrared (Vis/NIR) spectroscopic device was used to sort D’Agen plums harvested around the traditional commercial harvest date. The chlorophyll absorbance index was found to be capable of segregating plums into classes of maturity according to various concentrations of soluble solids and fruit compression strenght values. Fruits with a chlorophyll absorbance index value of less than 1.59 showed no differences in flesh firmness. Plums harvested with chlorophyll absorbance index values of 1.20-1.29 had a fruit compression strenght of 1.25 N and a soluble solids concentration of 23.3%. Both of these values correspond to adequate thresholds for harvesting plums for industrial purposes. The chlorophyll absorbance index may be valuable in allowing the identification of high-quality plums either for fresh consumption or industrial processing.

Proteomic analysis of a segregant population reveals candidate proteins linked to mealiness in peach

Peaches are stored at low temperatures to delay ripening and increase postharvest life. However some varieties are susceptible to chilling injury,which leads to fruit mealiness, browning and flesh bleeding. In order to identify potentialmarkers associated with chilling injury,we performed proteomic analyses on a segregating population with contrasting susceptibility to chilling-induced mealiness. Chilling-induced mealiness was assessed by measuring juiciness in fruits that have been stored in cold and then allowed to ripen. Fruitmesocarp and leaf proteome from contrasting segregants were analyzed using 2-DE gels. Comparison of protein abundance between segregants revealed 133 spots from fruit mesocarp and 36 from leaf. Thirty four fruit mesocarp proteins were identified from these spots. Most of these proteins were related to ethylene synthesis, ABA response and stress response. Leaf protein analyses identified 22 proteins, most of which related to energy metabolism. Some of the genes that code for these proteins have been previously correlated with chilling injury through transcript analyses and co-segregation with mealiness QTLs. The results from this study, further deciphers the molecular mechanisms associated with chilling response in peach fruit, and identifies candidate proteins linked to mealiness in peach which may be used as putative markers for this trait.

Does the maturity at harvest affect quality and sensory attributes of peaches and nectarines

Abstract Fruit quality has been described as a property that depends on many factors. Harvest time is one such factor, described as negatively affecting the fruit quality of peaches and nectarines when carried out at early stages of maturity. In order to assess this, fruit from peach cultivars ‘2B40’, ‘Elegant Lady’ and ‘Sweet September’, and nectarine cultivars ‘Antares’ and ‘5A29’ were harvested at three maturity levels, based on ground skin colour (M1 = green-yellow, M2 = pale yellow and M3 = yellow), and evaluated at harvest and after a ripening period. Evaluations included instrumental characterization, sensorial analysis and e-nose. Flesh firmness was the parameter that best segregated the three maturity levels. Sensorial attributes and acceptability did not show differences between stages of maturity, while e-nose data clustered M1, M2 and M3 into different groups. These results suggest that the maturity level at harvest, within the range evaluated in this research, does not affect the sensory quality of the product, in spite of the aroma assessed with an e-nose revealing differences among them.

Perceived quality in fresh peaches: an approach through structural equation modeling

Uno de los topicos que mas atrae la atencion de los actores de la cadena productiva de fruta fresca, es entender los requerimientos de calidad que los consumidores de fruta fresca consideran en sus procesos de decision de compra. En esta perspectiva, esta investigacion se ha orientado hacia la identificacion de relaciones significativas entre atributos que podrian explicar como percibe la calidad un consumidor de duraznos en estado fresco. Asimismo, se ha considerado focalizar el estudio en el durazno debido basicamente a que es una especie de la cual no se tiene conocimiento en terminos de cuales son los las senales de calidad que busca el consumidor cuando desarrolla sus preferencias. En virtud de lo senalado, el objetivo del presente es desarrollar un modelo que contribuya a explicar la calidad de duraznos frescos segun la percepcion de consumidores espanoles. Para ello, se ha recurrido a un modelo teorico, el cual explica la calidad mediante un conjunto de atributos intrinsecos y extrinsecos. La fuente principal de informacion fue una encuesta de preguntas cerradas aplicada de forma presencial a una muestra no probabilistica de 192 consumidores espanoles. La metodologia asociada al objetivo expuesto fue un analisis de ecuaciones estructurales, el cual fue sometido a un conjunto de indicadores de bondad de ajuste del modelo (CMIN/DF, RMR, NFI, RFI, RMSEA, HOELTER, entre otros). De tal modo, ajustandose a los valores recomendados por la literatura, se identifico un modelo que explica la calidad en los consumidores estudiados, mediante dos conjuntos de atributos: extrinsecos y extrinsecos. Finalmente, se determinaron relaciones significativas y altas, entre calidad percibida y homogeneidad de la fruta y, entre calidad percibida y disponibilidad en supermercados y fruterias.

Acclimation to sun and shade of three accessions of the Chilean native berry-crop murta

Murta (Ugni molinae Turcz.) is an evergreen shrub of the native forest understorey of southern Chile that produces berries which are consumed in the local markets. Because of the natural adaptation of murta to growing under the shade of trees, we propose that an adequate way of domesticating this species would be its cultivation in agroforestry systems. In order to assess the suitability of three murta accessions from different regions in southern Chile for their cultivation in such systems, we established a trial in which these accessions were submitted to six light transmittance levels (20%–100% of full solar irradiance) from planting in spring to the following autumn. Optimum growth, as assessed through dry mass accumulation and emission of branches and metamers, was achieved at moderate light transmittance levels (50%–65%). These growth traits showed stable positive responses to the relative amount of light intercepted by the plants (as estimated from plant structural traits) up to these optimum light transmittance levels and diverged to lower values thereafter. These stable relationships suggest that the differences in plant growth at low and moderate light transmittance levels can be attributed to restrictions of photosynthesis by light availability. The reduction in growth for higher light transmittance levels may be partly attributed to photoinhibition as suggested by reduced chlorophyll content and relatively low increments in carotenoid content in leaves at high light transmittance levels.

Genotyping by Sequencing for SNP-Based Linkage Analysis and Identification of QTLs Linked to Fruit Quality Traits in Japanese Plum (Prunus salicina Lindl.)

Marker-assisted selection (MAS) in stone fruit (Prunus species) breeding is currently difficult to achieve due to the polygenic nature of the most relevant agronomic traits linked to fruit quality. Genotyping by sequencing (GBS), however, provides a large quantity of useful data suitable for fine mapping using Single Nucleotide Polymorphisms (SNPs) from a reference genome. In this study, GBS was used to genotype 272 seedlings of three F1 Japanese plum (Prunus salicina Lindl) progenies derived from crossing “98–99” (as a common female parent) with “Angeleno,” “September King,” and “September Queen” as male parents. Raw sequences were aligned to the Peach genome v1, and 42,909 filtered SNPs were obtained after sequence alignment. In addition, 153 seedlings from the “98–99” × “Angeleno” cross were used to develop a genetic map for each parent. A total of 981 SNPs were mapped (479 for “98–99” and 502 for “Angeleno”), covering a genetic distance of 688.8 and 647.03 cM, respectively. Fifty five seedlings from this progeny were phenotyped for different fruit quality traits including ripening time, fruit weight, fruit shape, chlorophyll index, skin color, flesh color, over color, firmness, and soluble solids content in the years 2015 and 2016. Linkage-based QTL analysis allowed the identification of genomic regions significantly associated with ripening time (LG4 of both parents and both phenotyping years), fruit skin color (LG3 and LG4 of both parents and both years), chlorophyll degradation index (LG3 of both parents in 2015) and fruit weight (LG7 of both parents in 2016). These results represent a promising situation for GBS in the identification of SNP variants associated to fruit quality traits, potentially applicable in breeding programs through MAS, in a highly heterozygous crop species such as Japanese plum.