Mejoramiento de la calidad del fruto por la incorporación de genes de especies silvestres en el tomate (Solanum lycopersicum L.) / Fruit quality improvement through the incorporation of wild species genes in the tomato (Solanum lycopersicum L.)

RESUMEN En el mejoramiento del tomate (Solanum lycopersicum L.) se ha logrado un incremento significativo para el rendimiento y otras características productivas en un período corto de tiempo. Como consecuencia se redujo notablemente la diversidad genética. Si bien el germoplasma silvestre se ha utilizado principalmente como fuente de genes de resistencia para enfermedades y plagas, nuestro grupo inició en la década de 1990, un programa de mejoramiento genético en tomate para mejorar la calidad del fruto con especial énfasis en incrementar la vida poscosecha y también ampliar la variabilidad genética con la incorporación de estos genes al gran cultivo. Hemos desarrollado diferentes poblaciones a partir del cruzamiento interespecífico entre el cultivar argentino Caimanta de S. lycopersicum y la accesión LA0722 de S. pimpinellifolium L. Mediante la generación de cruzamientos entre estos padres selectos y el posterior avance generacional de la selección se ha tratado de dilucidar las bases genéticas que definen la calidad del fruto. Para ello se integraron al programa de mejoramiento información obtenida de datos genómicos, posgenómicos y bioinformáticos. Al mismo tiempo hemos desarrollado cuatro nuevos cultivares con características de calidad de fruto superiores al ser comparados con híbridos comerciales. Para conservar y estudiar la diversidad del cultivo también estamos desarrollado una colección de germoplasma que en la actualidad cuenta con 162 genotipos de tomate de diferentes especies y orígenes. Además, se ha iniciado la transferencia directa de plantines a huertas urbanas y periurbanas para favorecer el acceso a semillas de estos cultivares desarrollados en instituciones públicas.

ABSTRACT The genetic improvement of tomato (Solanum lycopersicum L.) has achieved an increase for yield and other agronomic traits in a short period of time. As a consequence, genetic diversity has been notably reduced. Wild germplasm has been mostly used as a source of resistance genes for diseases and pests. Our group started in the 1990' a breeding program in tomato for improving fruit quality, with special emphasis on increasing fruit shelf life and broadening the genetic variability with the incorporation of wild genes. We have developed different populations from the interspecific cross between the Argentine cultivar Caimanta of S. lycopersicum and the accession LA0722 of S. pimpinellifolium L. Through crosses between these selected parents and the subsequent generational selection advance, we attempted to elucidate the genetic bases that underlie tomato fruit quality. To do that, we use state-of-the-art technology available in the field of genetics and breeding programs, including genomic, post-genomic and bioinformatic data. At the same time, we have developed four new cultivars with improved fruit quality traits compared to commercial hybrids. To conserve and study the tomato diversity, we have developed a germplasm collection that currently contains 162 tomato genotypes from different species and origins. In addition, we have started a direct transfer of our cultivars to urban and peri-urban community orchards to facilitate them the access to genotypes that were developed in Argentine public institutions.

Pericarp polypeptides and SRAP markers associated with fruit quality traits in an interspecific tomato backcross.

The aim of this study was to detect polypeptides and genomic regions associated with fruit quality traits in a backcross generation using as parent the Argentinean cultivated tomato Caimanta of Solanum lycopersicum and the wild accession LA722 of S. pimpinellifolium. We tested two types of molecular marker: polypeptide profile (at two ripening stages, mature green and red ripe) and SRAP (sequence-related amplified polymorphism). A polypeptide of 45 kDa present in the wild parents at the mature green stage was associated with larger fruit and long shelf life. Some amplification fragments from SRAP markers were associated with more than one quality trait such as fruit color, firmness, titratable acidity, and fruit soluble solids content. This study demonstrated for the first time the usefulness of the polypeptide profiles of pericarp and SRAP markers in finding associations with quality fruit traits in a tomato backcross generation.

Phenolic compounds: their journey after intake.

Plant foods are rich in phenolic compounds (PCs) that display multifaceted bioactions in health promotion and disease prevention. To exert their bioactivity, they must be delivered to and absorbed in the gastrointestinal (GI) tract, transported in circulation, and reach the target tissues. During the journey from ingestion to target tissues and final excretion, PCs are subjected to modifications by many factors during their absorption, deposition, metabolism and excretion (ADME) and consequently their bioefficacy may be modified. Consistent with all nutrients in foods, PCs must first be released from the food matrix through mechanical, chemical, and enzymatic forces to facilitate absorption along the GI tract, particularly in the upper small intestine section. Further, glycosylation of PCs directs the route of their absorption with glycones being transported through active transportation and aglycones through passive diffusion. After enteral absorption, the majority of PCs are extensively transformed by the detoxification system in enterocytes and liver for excretion in bile, feces, and urine. The journey of PCs from consumption to excretion appears to be comparable to many synthetic medications, but with some dissimilarities in their fate and bioactivity after phase I and II metabolism. The overall bioavailability of PCs is determined mainly by chemical characteristics, bioaccessibility, and ADME. In this review, factors accounting for variation in PCs bioavailability are discussed because this information is crucial for validation of the health benefits of PCs and their mechanism of action.

Poly-L-asparagine nanocapsules as anticancer drug delivery vehicles.

This work presents for the first time the development of novel poly-L-asparagine (PASN) nanocapsules and the in vitro evaluation of their potential as anticancer drug delivery systems. The design of PASN nanocapsules was inspired by the well-known avidity of cancer cells for the amino acid L-asparagine together with the expected ability of this hydrophilic polymer to escape to the mononuclear phagocytic system. Besides, these nanocapsules have an oily reservoir, which enables the efficient encapsulation of lipophilic drugs. PASN nanocapsules were obtained by an emulsification-polymer layer deposition process, which involves using a cationic surfactant as a bridge for the interaction of PASN with the lipid core. PASN nanocapsules showed sizes of around 170-200 nm and negative zeta potential values (around -20 mV to -40 mV). The model anticancer drug docetaxel was efficiently encapsulated (around 75%) and retained within the nanocapsule's structure upon dilution in a simulated physiological medium. Moreover, these nanocapsules exhibited the ability to interact with the NCI-H460 human cancer cells and to enhance the cellular toxicity of the anticancer drug. All these features together with their adequate stability profile render these nanocapsules a new attractive platform for anticancer intracellular drug delivery.

Mapping of two suppressors of OVATE (sov) loci in tomato.

Tomato fruit shape varies significantly in the cultivated germplasm. To a large extent, this variation can be explained by four genes including OVATE. While most varieties with the OVATE mutation bear elongated fruits, some accessions carry round fruit, suggesting the existence of suppressors of OVATE in the germplasm. We developed three intraspecific F2 populations with parents that carried the OVATE mutation but differed in fruit shape. We used a bulk segregant analysis approach and genotyped the extreme classes using a high-throughput genotyping platform, the SolCAP Infinium Assay. The analyses revealed segregation at two quantitative trait loci (QTLs), sov1 and sov2. These loci were confirmed by genotyping and QTL analyses of the entire population. More precise location of those loci using progeny testing confirmed that sov1 on chromosome 10 controlled obovoid and elongated shape, whereas sov2 on chromosome 11 controlled mainly elongated fruit shape. Both loci were located in intervals of <2.4 Mb on their respective chromosomes.

Síndrome CCC (cuello corto, campodactilia, cardiopatía) con variabilidad: nuevo síndrome autosómico dominante / Syndrome CCC (short neck, camptodactily, cardiopathy) with variability expression: a new autosomic dominant syndrome

Se presenta el cuadro clínico no descrito anteriormente de una familia en la que se encontraron 16 personas que mostraban, en forma constante, cuello corto y ancho, cardiopatía a expensas del ventrículo izquierdo y camptodactilia con hipoplasia de los pliegues de flexión. Todos tenían talla baja con variabilidad en su expresión. Otros datos no constantes fueron paladar alto, depresión del puente nasal, micrognatia, cúbito varo, posición dental anormal e hiperplasia gingival. Al tomar en cuenta las malformaciones constantes se le ha denominado "sindrome CCC", siglas que corresponden a cuello corto, cardiopatía y camptodactilia.

Effect of acute reversal of experimentally-induced ketoacidosis with sodium bicarbonate on the plasma concentrations of phosphorus and potassium.

To determine if ketoacidosis per se, or its reversal with NaHCO3, predisposes to hypophosphatemia, six conditioned dogs were infused for two hours with 3.0 mmol/kg body wt/hour of beta-hydroxybutyric acid, followed by 1.5 mmol/kg/hour of NaHCO3 for two hours. Acid infusion caused moderate decrements in blood pH and [HCO3], a 23 +/- 4% increase in plasma [P] (p less than 0.005), and a 15 +/- 3% decrease in plasma [K] (p less than 0.005). NaHCO3 administration returned blood pH and [HCO3] levels to or slightly greater than baseline. Plasma [P] decreased, but not below baseline, whereas plasma [K] remained below baseline, and underwent an additional small decline (p less than 0.01). We conclude that acute correction of experimental ketoacidosis with NaHCO3 reverses the characteristic hyperphosphatemia but does not induce hypophosphatemia. On the other hand, NaHCO3 administration appeared to contribute to the perpetuation of hypokalemia.

Effect of potassium depletion on acidosis-induced changes in plasma potassium concentration.

It is unknown whether acute metabolic acidosis causes increases in plasma potassium concentration despite pre-existing potassium depletion. In fact, it has long been assumed clinically that acidosis-induced acute hyperkalemia may be masked by potassium depletion. In order to assess this question, moderate to severe potassium depletion was produced in 7 female mongrel dogs (potassium-depleted group) over a 12-day period with injections of desoxycorticosterone acetate (DOCA), NaCl added to the drinking water, and a potassium-free diet. Six dogs (control group) received regular chow, identical NaCl supplements, and sham injections of DOCA. The achievement of potassium depletion was documented by significant differences between the two groups in urinary potassium and in muscle and plasma potassium levels (potassium-depleted group: 0.9 +/- 0.2 mEq/24 h, 19 +/- 3 mEq/100 g dry weight, 1.9 +/- 0.1 mEq/1; control group: 44 +/- 11 mEq/24 h [p less than 0.025], 30 +/- 1 mEq/100 g [p less than 0.005], 3.5 +/- 0.1 mEq/l [p less than 0.005]). There were no statistically significant differences between the groups in blood pH or [HCO3]. On day 13, an NH4Cl acid-load was given (5 mEq/kg body weight i.v. over 3 h in 0.45% NaCl using pentobarbital anesthesia). Following acid-loading, the increases in plasma [K] were significantly greater in the control group than in the potassium-depleted group only at 90 and 120 min. There were no significant differences in the maximal increases from baseline in plasma [K] (potassium-depleted group: 0.6 +/- 0.1 mEq/l, 31 +/- 6%; control group: 1.5 +/- 0.4 mEq/l, 41 +/- 10%).(ABSTRACT TRUNCATED AT 250 WORDS)