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.

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.

RESUMO: A disponibilidade de cultivares resistentes à imidazolinona (IMI) proporcionou uma opção eficaz para o controle de plantas daninhas em sistemas de produção de trigo. Os herbicidas IMI controlam várias plantas daninhas, incluindo Avena fatua e Lolium multiflorum, as gramíneas mais frequentes nas culturas de trigo nos Pampas argentinos. O objetivo deste trabalho foi desenvolver um método sem solo que permita a fenotipagem rápida de resistência ao IMI em trigo. Avaliaram-se nove cultivares de trigo, diferentes na resistência ao IMI, por meio de um método de germinação entre folhas de papel. As concentrações de herbicidas necessárias para reduzir o comprimento da parte aérea e da raiz em 50% para cultivares resistentes foram > 75 vezes que as dos cultivares suscetíveis. A resposta de cultivares comerciais resistentes e suscetíveis, avaliada nos métodos entre folhas de papel e papel, foi superior a 100 mM de imazamox como dose discriminante. O fator Z’ foi calculado para a avaliação da qualidade dos métodos de triagem. Ambos os métodos de germinação mostraram Z’-fatores > 0, indicando que foram apropriados, porém o método entre folhas de papel permitiu economizar espaço na câmara de crescimento. Os testes de germinação foram úteis para distinguir entre plantas suscetíveis e resistentes portadoras de pelo menos um gene de resistência. O método rápido, simples e econômico descrito no presente estudo pode ser uma ferramenta importante para selecionar trigo resistente ao IMI em programas de melhoramento.

ABSTRACT: The availability of imidazolinone (IMI) resistant cultivars has provided an effective option for weed control in wheat production systems. IMI herbicides control several weeds, including Avena fatua and Lolium multiflorum, which are the most frequent grass weeds in wheat crops of the Argentine Pampas. The aim of this study was to develop a soil-less method that allows rapid phenotyping of IMI resistance in wheat. Nine wheat cultivars differing in IMI resistance were evaluated through a between-paper germination method. Herbicide concentrations required to reduce shoot and root length by 50% for resistant cultivars were > 75 fold that of the susceptible cultivars. The response of resistant and susceptible commercial cultivars was assessed in the between-paper and top-paper methods at 100 mM imazamox as discriminating dose. The Z’-factor was calculated for evaluation of the quality of the screening methods. Both germination methods showed Z’-factors > 0 indicating that the assays were appropriate but the between-paper method allowed to save space in the growth chamber. The germination methods were useful for distinguishing between susceptible and resistant plants carrying at least one resistance gene. The rapid, simple and cost-effective method described in the present study could be a potential tool when selecting for IMI resistance in wheat in breeding programs.

ABSTRACT The first commercial herbicide-resistant trait in sunflower (Helianthus annuus L.) is known as ‘Imisun’. Imidazolinone resistance in Imisun cultivars has been reported to be genetically controlled by a major gene (known as Imr1 or Ahasl1-1) and modifier genes. Imr1 is an allelic variant of the Ahasl1 locus that codes for the acetohydroxyacid synthase, which is the target site of these herbicides. The mechanism of resistance endowed by modifier genes has not been characterized and it could be related to non-target-site resistance. The objective of this study was to evaluate the role of cytochrome P450 monooxygenases (P450s) in Imisun resistance. The response to imazapyr herbicide in combination with P450s inhibitor malathion was evaluated in 2 Imisun lines, IMI-1 and RHA426. Malathion reduced herbicide efficacy in both lines, but IMI-1 was affected in a greater extent. A significant reduction in plant growth in response to P450s inhibitors 1-aminobenzotriazole and piperonyl butoxide treatment was detected in the Imisun line HA425. The increased susceptibility to imazapyr after P450s-inhibitor treatment indicates that herbicide metabolism by P450s is a mechanism involved in Imisun resistance. These results also suggest the involvement of different P450s isozymes in endowing resistance to imazapyr in Imisun cultivars.

The objective of this work was to study recombination of the productive and fruit quality traits in the segregating generation of the hybrid between a cultivated variety of Lycopersicon esculentum homozygous for nor and the accession LA1385 of L. esculentum var. cerasiforme using multivariate statistical analysis. F1 and F2 generations and the parents were evaluated for vegetative and productive traits (internode length, stem perimeter at the basal, middle and apical parts, number of flowers per cluster, number of clusters per plant and days to harvest) and quality fruit traits (weight, shape, soluble solids content, acidity, firmness, color and shelf life). A canonical correlation between vegetative and productive traits and those of fruit quality and clustering for fruit traits performed with the F1 and F2 and the parents were used. The productive and fruit quality traits showed recombination in the segregating generation. Shelf life was the most outstanding fruit trait to discriminate groups in the F2. For three cluster levels each group of F2 individuals behaved each one of the parents and the F1.

El objetivo del trabajo fue estudiar en la generación segregante del híbrido entre una cultivar de Lycopersicon esculentum homocigota para el gen nor y la accesión LA1385 de L. esculentum var. cerasiforme, la recombinación de caracteres productivos y de calidad de fruto a través de las metodologías de análisis multivariado. En las generaciones F1 y F2 y en los progenitores se evaluaron caracteres vegetativos y productivos (longitud de entrenudos, perímetro del tallo en las partes basal, media y apical, número de flores por inflorescencia, número de inflorescencias por planta y días a cosecha) y de calidad de fruto (peso, forma, sólidos solubles, acidez, firmeza, color y vida poscosecha). Se utilizaron las correlaciones canónicas entre los caracteres vegetativos y productivos y los de calidad de fruto y también un análisis de agrupamiento para las características del fruto, incluyendo los progenitores, la F1 y la F2. Estos análisis permitieron demostrar que las características productivas y de calidad de fruto recombinaron en la generación segregante. La vida poscosecha fue la característica de los frutos más importante para discriminar grupos en la F2. Para tres niveles de agrupamiento cada grupo de individuos F2 se comportó como alguno de los progenitores o la F1.

O objetivo principal deste trabalho foi determinar as variáveis que melhor explicam a variação entre indivíduos dentro da população de aspargos originária da cultivar Argenteüil e selecionar plantas superiores para compor novas populações. O ensaio, composto por 1280 plantas, foi instalado no campo experimental da Facultad de Ciencias Agrarias de la Universidad Nacional de Rosario, Santa Fe, Argentina, em 1996. Durante os anos de 1997 e 1998, foram avaliadas as variáveis: número de turiões por planta (TU); peso médio do turião (PM); diâmetro do turião (DI); produção total por planta (RE); produção comercial por planta (RM); número de dias para início da colheita (DAC); número de hastes por planta (NUTA); altura da haste principal (ALT) e peso fresco da massa verde (MASAV). De acordo com a análise de componentes principais, as variáveis RE, RM, PM, DI e TU, são responsáveis por 60% da variação existente dentro da população avaliada. A análise de agrupamento baseada nestas variáveis, permitiu a identificação de cinco grupos distintos para os dois sexos. Os grupos G5 de plantas estaminadas e G5 de plantas pistiladas (7,51% da população total) apresentaram as melhores características de RE e qualidade. Destes grupos, foram selecionadas 6 plantas estaminadas e 8 plantas pistiladas para serem utilizadas como genitores no programa de melhoramento de aspargos.

The principal aim of this experiment was to ascertain what the variables are which best explain the variations among individuals within the populations of asparagus which originates from the cultivar Argenteüil and as a result select better plants to form new populations. The test, using 1,280 plants, was carried out at he experimental farm in the Facultad Ciencias Agrarias de la Universidad Nacional de Rosario, Santa Fé, Argentina, in 1996. During 1997 and 1998 the number of spears per plant (TU), the mean weight of spears (PM), mean diameter of spears (DI) total yield (RE), marketable yield (RM), days to first harvest (DAC), number of stalks (NUTA), plant height (ALT) and fresh weight of the fern (MASAV) were measured. According to an analysis of the principal components, the variables RE, RM, PM, DI and TU were responsible for 60% of the variation that exists within the population evaluated.

The genetic variability for the fruit's shelf-life and weight was evaluated in twenty-six F3 families derived from an interspecific hybrid between the cv. Caimanta of Lycopersicon esculentum Mill. and the line LA722 of L. pimpinellifolium (Jusl.) Mill. The means for fruit's shelf-life were 8, 15, 18 and 13 days and for fruit weight were 52.17 g; 0.94 g; 4.45 g and 6.41 g in 'Caimanta', LA722, the F1 and in the F3 generations, respectively. No family was similar to the progenitor 'Caimanta' for fruit's shelf-life and only one family showed a shelf-life similar to the F1 generation mean. For fruit weight, four families were similar to the F1 generation mean and the F3 families differed from both parent means. The F3 family with the greatest values for fruit weight and shelf-life showed a fruit weight mean of 20.15 g and shelf-life period of 21.55 days. The smaller fruit weight was 2.81 g and the smaller shelf-life period for another family was 9.98 days. The wide genetic variability found for both traits between the families will permit to select divergent genotypes.

Se evaluó la variabilidad genética para la vida postcosecha y el peso de los frutos en veintiséis familias F3 de un híbrido interespecífico entre la cv. Caimanta de Lycopersicon esculentum Mill. y la línea LA722 de L. pimpinellifolium (Jusl.) Mill. con el objeto de obtener genotipos divergentes para ambos caracteres. Los promedios de días de vida postcosecha fueron 8, 15, 18 y 13 y de peso en gramos fueron 52,17, 0,94, 4,45 y 6,41 para cv. Caimanta, LA722, la F1 y la generación F3, respectivamente. Ninguna familia fue similar al progenitor `Caimanta' para el carácter días de vida postcosecha y sólo una familia tuvo una vida postcosecha como la F1. Para el peso de los frutos, cuatro familias fueron similares a la F1 y ninguna fue como los progenitores. La familia con peso de los frutos con 20,15 g y vida postcosecha de 21,5 días fue la que presentó mayores valores. El menor peso de los frutos fue en una familia con 2,81 g y el de menor vida postcosecha en una con 9,98 días. La amplia variabilidad genética encontrada para ambos caracteres entre las familias permitirá obtener genotipos divergentes.

A variabilidade intra e interespecífica foi avaliada no gênero Lycopersicon para as variáveis: taxa de produtividade (PR, número total de brotos/número total de culturas), percentagem de regeneração (%R, número de culturas que regeneraram brotos ou primórdios/número total de culturas) e percentagem de calo (%C, número de culturas que só desenvolveram calo/número total de culturas). Os explantes foliares de vários genótipos de L. esculentum, L. esculentum var. ceraciforme, L. pimpinellifolium e L. peruvianum foram colocados em meio de cultura Murashige and Skoog (Physiol. Plant. 15: 473-493, 1962) + 0.175 mg/l AIA + 2.25 mg/l BA. Detectaram-se diferenças significativas entre espécies e entre genótipos de uma mesma espécie, apresentando genótipos de diferentes espécies a mesma resposta.

Intra and interspecific variability was measured in the genus Lycopersicon for the traits: productivity rate (PR, total number of regenerated shoots/total number of cultures), regeneration percentage (%R, number of cultures regenerating shoots or primordia/total number of cultures) and callus percentage (%C, number of cultures only producing callus/total number of cultures). Leaf explants from various genotypes of L. esculentum, L. esculentum var. cerasiforme, L. pimpinellifolium and L. peruvianum were placed on Murashige and Skoog (Physiol. Plant. 15: 473-493, 1962) medium + 0.175 mg/l IAA + 2.25 mg/l BA. Significant differences among species and among genotypes within the same species were found, while genotypes from different species showed similar responses.