Molecular genetics of quantitative traits in tomato diallel crosses

The purpose of this research was to evaluate molecular markers and some quantitative fruit traits,  in a complete diallel cross without reciprocals, among five tomato recombinant inbred lines and their hybrids. Amplified fragment length polymorphism  (AFLP) and pericarp polypeptide profiles were obtained in four stages of fruit maturity of 15  genotypes. Among other traits, fruit weight, titratable acidity, pH, shelf life, and firmness were evaluated. The percentages of polymorphism for molecular markers and for the genetic variability for quantitative characters were calculated in the recombinant lines, hybrids and total genotypes. Cluster analyses were done for each level of genetic variation. The percentage of polymorphism varied between 34 and 54% for AFLP, and between 40 and 78% for polypeptide profiles. Higher polymorphism was observed in the group of hybrids. The genetic variability was 100% for titratable acidity and 34% for firmness, and the highest values were found in the parents. The genetic similarity varied among genotypes according to the level of genetic variation; however, the clustering consistency of some recombinant lines and their hybrids was conserved, which evidenced associations among molecular and phenotypic data.El objetivo de este trabajo fue evaluar marcadores moleculares y caracteres cuantitativos en un cruzamiento dialélico completo sin recíprocos, entre cinco líneas recombinantes de tomate y sus híbridos. Se obtuvieron perfiles de AFLP ("amplified fragment length polymorphism") y de polipéptidos del pericarpio en cuatro estados de madurez del fruto de 15 genotipos. Se evaluaron, entre otros: peso, acidez titulable, pH, vida poscosecha y firmeza. Se calculó el porcentaje de polimorfismo para los marcadores moleculares y el porcentaje de variabilidad genética para los caracteres cuantitativos en el grupo de líneas recombinantes, el de híbridos y el conjunto de genotipos. Se realizaron análisis de agrupamiento con cada nivel de variación genética. Para AFLP, el porcentaje de polimorfismo varió entre 34 y 54% y, para los perfiles polipeptídicos, entre 40 y 78%. Mayor polimorfismo fue observado en el grupo de híbridos. La variabilidad genética fue de 100% para acidez y 34% para firmeza, con los mayores valores en los parentales. La similitud genética varió entre los genotipos según el nivel de variación genética; pero la consistencia en el agrupamiento de algunas líneas recombinantes y sus híbridos fue conservada, lo que evidenció asociaciones entre los datos moleculares y fenotípicos.The purpose of this research was to evaluate molecular markers and some quantitative fruit traits,  in a complete diallel cross without reciprocals, among five tomato recombinant inbred lines and their hybrids. Amplified fragment length polymorphism  (AFLP) and pericarp polypeptide profiles were obtained in four stages of fruit maturity of 15  genotypes. Among other traits, fruit weight, titratable acidity, pH, shelf life, and firmness were evaluated. The percentages of polymorphism for molecular markers and for the genetic variability for quantitative characters were calculated in the recombinant lines, hybrids and total genotypes. Cluster analyses were done for each level of genetic variation. The percentage of polymorphism varied between 34 and 54% for AFLP, and between 40 and 78% for polypeptide profiles. Higher polymorphism was observed in the group of hybrids. The genetic variability was 100% for titratable acidity and 34% for firmness, and the highest values were found in the parents. The genetic similarity varied among genotypes according to the level of genetic variation; however, the clustering consistency of some recombinant lines and their hybrids was conserved, which evidenced associations among molecular and phenotypic data

Preservation of Solanum pimpinellifolium genomic fragments in recombinant genotypes increase tomato fruit quality

Five recombinant inbred lines obtained from the F2 generation of an interspecific cross between cultivar, Caimanta (Cai, Solanum lycopersicum) and wild accession, LA722 (P, S. pimpinellifolium) were crossed to obtain the second cycle hybrids (SCH). Eleven fruit quality traits were assessed in evaluating phenotypic variability among genotypes P, Cai, F1 (Cai × P), five RILs, and 10 SCH. One of the five recombinant inbred lines and three SCH had higher values than P, as the best geno- type for shelf life. Sequence-related amplified polymorphism was used as the molecular method for detecting polymorphism among these 18 genotypes. The percentage of polymorphism in RILs and SCH was 61% and 66% respectively. Moreover, some bands detected in P were present in SCH. Several multivariate analyses were performed to find agreement between the phenotypic variability observed for fruit quality traits and the polymorphism obtained from sequence-related amplified poly- morphism markers. A general Procrustes analysis estimated that there was a consensus proportion of 75% between phenotypic and molecular data. There was considerable preservation of some bands from the wild genotype, which could increase the variability in fruit quality traits in populations where the genetic diversity is limited.Fil: Mahuad, Sabina Lara. Universidad Nacional de Rosario. Facultad de Cs.agrarias. Departamento de Biologia. Cat.de Genetica; Argentina;Fil: Pratta, Guillermo Raúl. Universidad Nacional de Rosario. Facultad de Cs.agrarias. Departamento de Biologia. Cat.de Genetica; Argentina;Fil: Rodríguez, Gustavo Rubén. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Humanidades; Argentina;Fil: Zorzoli, Roxana. Universidad Nacional de Rosario. Facultad de Cs.agrarias. Departamento de Biologia. Cat.de Genetica, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Picardi, Liliana Amelia. Universidad Nacional de Rosario. Facultad de Cs.agrarias. Departamento de Biologia. Cat.de Genetica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Tomato second cycle hybrids as a source of genetic variability for fruit quality traits

The objective of this study was to investigate the phenotypic and molecular variability in a F2 generation derived from a SCH (Second Cycle Hybrid) in order to detect QTLs for some fruit traits of tomato. Genome coverage at different levels was achieved by three types of molecular markers (polypeptides, sequence-related amplified polymorphism-SRAP and amplified restriction fragment polymorphism - AFLP). Different degrees of polymorphism were detected by SRAP and AFLP at the DNA structure level and also by polypeptides at the DNA expression level. The first two markers, associated with phenotypic variation, detected QTLs involved in important agronomic traits such as fruit shelf life, soluble solids content, pH, and titratable acidity. New gene blocks originated by recombination during the first cycle of crossing were detected. This study confirmed that the observed phenotypic differences represent a new gene rearrangement and that these new gene blocks are responsible for the presence of the genetic variability detected for these traits.IICAR-CONICET-UNR (Instituto de Investigaciones en Ciencias Agrarias de Rosario - Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de Rosario). Cátedra de Genética, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario

Genética molecular de caracteres cuantitativos en cruzamientos dialélicos de tomate

El objetivo de este trabajo fue evaluar marcadores moleculares y caracteres cuantitativos en un cruzamiento dialélico completo sin recíprocos, entre cinco líneas recombinantes de tomate y sus híbridos. Se obtuvieron perfiles de AFLP ("amplified fragment length polymorphism") y de polipéptidos del pericarpio en cuatro estados de madurez del fruto de 15 genotipos. Se evaluaron, entre otros: peso, acidez titulable, pH, vida poscosecha y firmeza. Se calculó el porcentaje de polimorfismo para los marcadores moleculares y el porcentaje de variabilidad genética para los caracteres cuantitativos en el grupo de líneas recombinantes, el de híbridos y el conjunto de genotipos. Se realizaron análisis de agrupamiento con cada nivel de variación genética. Para AFLP, el porcentaje de polimorfismo varió entre 34 y 54% y, para los perfiles polipeptídicos, entre 40 y 78%. Mayor polimorfismo fue observado en el grupo de híbridos. La variabilidad genética fue de 100% para acidez y 34% para firmeza, con los mayores valores en los parentales. La similitud genética varió entre los genotipos según el nivel de variación genética; pero la consistencia en el agrupamiento de algunas líneas recombinantes y sus híbridos fue conservada, lo que evidenció asociaciones entre los datos moleculares y fenotípicos