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.
Soybean stem canker (SSC) is caused by two varieties of the fungus
Diaporthe phaseolorum
: var.
meridionalis
(
Dpm
) and var.
caulivora
(
Dpc
). The objective was to identify and characterize the ...mode of inheritance of
Rdc
genes through a classical Mendelian analysis. Resistant (R) and susceptible (S) genotypes were used to make 288 RxS and 132 RxR crosses, including their reciprocals. Segregating F
2
generations were obtained by self-fertilization of the respective F
1
. The incorporation of codominant molecular markers (Single Nucleotide Polymorphism, SNP) allowed the molecular validation of 48.75% of F
1
heterozygous individuals. Parents (R and S), F
1
individuals, and F
2:3
families (Progeny Test, PT) from COD 1–258-2 population were inoculated with an isolate of
Dpc
(
Dpc
16), previously identified morphologically and molecularly. The assay showed 21 F
2:3
families categorized as R, 42 segregated R and S, and 11 as S. Particularly, this F
3
population showed 466 individuals R and 274 S. The chi-square goodness of fit test verified that phenotypic segregation for individual plants in F
3
adjusted to a 5:3 ratio (R:S) and the PT results corresponded to the genotypic ratios (1RR: 2Rr: 1rr) of F
2
individuals. Results allowed the identification of a major resistance gene of simple Mendelian inheritance to SSC that was named
Rdc1
. Also, independent segregation 9:3:3:1 was verified between this
Rdc1
gene and the gene that regulates flower colour, a typical phenotypic marker in soybean. Based on literature review, this is the first report on resistance genes (
Rdc
) identified for SSC caused by
Dpc
.
In an asexually reproducing hybrid such as banana (Musa spp.), the assessment of clones in the short term is limited because replications are frequently unavailable in the proper number. The aim of ...this work is to propose the Multiple Factor Analysis of Mixed Data (MFAmix) as a tool for establishing objective criteria to identify banana clones that preserve variability for qualitative and quantitative variables. In the long term, the aim is the development of a banana germplasm bank. MFAmix was applied on a population composed of 124 banana clones collected from different farmers’ fields and four controls. Two groups of variables related to the agronomic aptitude of the clones were evaluated, one composed of nine quantitative variables, and the other, composed of three dichotomous qualitative variables. A Selection Index (SI) was built from the MFAmix coordinates in order to rank the clones and select a subset that allows to preserve the existing genetic variability. The first two axes of MFAmix explained a 49.47% of the total data variability. The set of the banana clones was successfully characterized based on quantitative and qualitative variables. In the long term, the creation of a banana germplasm bank should consider the height and diameter of the plant, the rachis bunch weight and the hands weight, and the qualitative variable plant leafiness.
Key words: asexual hybrid, collection of germplasm, multivariate analysis, Musaceae.
•Genotype variation for transcript profiles was found in tomato ripening by cDNA-AFLP.•Differential gene expression supported genetic variability for fruit quality traits.•Gene expression of S. ...pimpinellifolium LA722 is different at early stage of ripening.•A nor mutant homozygote of S. lycopersicum had the lowest polymorphism along ripening.•Genetic control of shelf life is different in wild than in accessions carrying nor gene.
The ripening stage at harvest time determines the tomato fruit quality. After the fruit achieves its maximum size several metabolic changes of typically climacteric fruits are produced. Two cultivated genotypes of Solanum lycopersicum (Caimanta and 804627), with normal and altered fruit ripening, respectively and two accession, LA1385 of S. lycopersicum var. cerasiforme and LA722 of S. pimpinellifolium, with genes that prolong fruit shelf life, were tested to: 1) characterize and make a comparatively analysis for the transcriptome at different fruit ripening stages in genotypes that differ in fruit shelf life by cDNA-AFLP; and 2) provide further insight into the relationship between the extreme phenotypic differences for ripening among the genotypes through changes at transcriptomic level. Fruits at the breaker stage (B) were evaluated for fruit weight, firmness and fruit shelf life. The elapsed days between mature green (MG) and breaker stages Days (MG-B) as well as the elapsed days between B and red ripe (RR) stages Days (B-RR) were recorded. Comparison among ripening stages showed a great polymorphism related to the changes in gene expression. For all genotypes the transition from B to RR stages had higher polymorphism than the transition from MG to B. It was observed a great genetic variability for the phenotypic traits in agreement with the changes of gene expression. Moreover, it was observed that the transcriptome expression profiles in the initial and intermediate stages during ripening (MG and B) are more important to characterize genotypes. The wild species which have long shelf life do not show as drastic changes in gene expression as the cultivar with altered ripening that carrythe nor gene. These results suggest that the expressed or silenced genes could be involved, in some way, in the determination of the phenotypic traits evaluated in this study.
The small heat shock proteins (sHSPs) have been found to play a critical role in physiological stress conditions in protecting proteins from irreversible aggregation. To characterize the gene ...expression profile of four sHsps with a tandem gene structure arrangement in the domesticated Solanum lycopersicum (Heinz 1706) genome and its wild close relative Solanum pimpinellifolium (LA1589), differential gene expression analysis using RNA-Seq was conducted in three ripening stages in both cultivars fruits. Gene promoter analysis was performed to explain the heterogeneous pattern of gene expression found for these tandem duplicated sHsps. In silico analysis results contribute to refocus wet experiment analysis in tomato sHsp family proteins.
La región subtropical húmeda de la provincia de Formosa, en el Nordeste Argentino (Lat. -25,2024130; Long. -58,1212980), presenta una zona de condiciones climáticas para el cultivo de banana (Mussa ...spp.). Los materiales de este cultivo son una mezcla de clones indiferenciados del subgrupo Cavendish. En la selección de material genético adaptado, el primer enfoque fue el análisis sobre las condiciones agroclimáticas en las cuales deberá desarrollarse el material, en producción hacía el 2025–2030. El segundo enfoque fue determinar el grado de polimorfismo fenotípico y molecular existente entre los clones cultivados por Agricultores Familiares. En 2012 se marcaron, en la región subtropical norte de Formosa, 684 clones que mostraron estabilidad de rendimiento. Los criterios de selección fueron resiliencia, ciclo, rendimiento y forma de las manos. Un total de 140 clones seleccionados se implantaron en diseño estadístico aumentado. Con cuatro ciclos de producción, 36 variables (fenológicas, comportamiento a campo y productivas) registradas, marcadores moleculares y datos climáticos se construyó un índice de selección, del cual se desprenden tres Variedades Sintéticas, cada una de ellas conformadas por cuatro Líneas Avanzadas Inta (LAI). En las tres variedades se ha tenido especial atención a las características comerciales, algo esencial para llegar a los mercados. La selección de materiales con características distintas es muy importante en un ambiente variable, las variedades sintéticas nos parecen adecuadas para este tipo de situación, otorgándole mayor resiliencia
In an asexually reproducing hybrid such as banana (Musa spp.), the assessment of clones in the short term is limited because replications are frequently unavailable in the proper number. The aim of ...this work is to propose the Multiple Factor Analysis of Mixed Data (MFAmix) as a tool for establishing objective criteria to identify banana clones that preserve variability for qualitative and quantitative variables. In the long term, the aim is the development of a banana germplasm bank. MFAmix was applied on a population composed of 124 banana clones collected from different farmers’ fields and four controls. Two groups of variables related to the agronomic aptitude of the clones were evaluated, one composed of nine quantitative variables, and the other, composed of three dichotomous qualitative variables. A Selection Index (SI) was built from the MFAmix coordinates in order to rank the clones and select a subset that allows to preserve the existing genetic variability. The first two axes of MFAmix explained a 49.47% of the total data variability. The set of the banana clones was successfully characterized based on quantitative and qualitative variables. In the long term, the creation of a banana germplasm bank should consider the height and diameter of the plant, the rachis bunch weight and the hands weight, and the qualitative variable plant leafiness.
Key words: asexual hybrid, collection of germplasm, multivariate analysis, Musaceae.
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.
Segregating progeny from the tomato Second Cycle Hybrids (SCH) that were obtained from crossing RIL (Recombinant Inbred Lines) allows the detection of new genetic combinations that could increase ...genetic variability in F2 populations. The objectives of the present study were to evaluate eleven tomato quality traits in a segregating F2 population obtained from a SCH and, then, to characterize the molecular diversity by six AFLP (Amplified Fragment Length Polymorphism) primer combinations. Different multivariate analyses were used to assess the degree of concordance among these two approaches to detect genetic variability. Sixty-nine F2 plants were obtained by selfing the SCH (ToUNR18xToUNR1). The parental RIL were derived from an interspecific cross between S. lycopersicum cv. Caimanta and the accession LA722 from S. pimpinellifolium after five cycles of antagonist and divergent selection for fruit weight and fruit shelf life. Principal Components Analysis (PCA) was applied to these data and we found that the first two components explained 77 % of variability. The molecular characterization showed 62 % of polymorphic bands. The Principal Coordinate Analysis (PCoA) showed that the first ten coordinates explained 75 % of variability. The Generalized Procrustes Analysis (GPA) showed a consensus between morphological and molecular data of 65 %. High values of broad sense heritability (H2 ) were found for all traits together with a high level of molecular polymorphism. The morphological and molecular data showed a high consensus proportion suggesting that it could be possible to detect QTL for these fruit traits exploring this new population.
Aún estamos viviendo la era de la Genética Molecular, cuya aplicación a estudios con enfoques integrados ha dado origen a la Genómica. Esta última, tanto en sus aspectos estructurales (organización ...del genoma) como funcionales (expresión del genoma, disciplina también conocida como Postgenómica) se ha aplicado al mejoramiento genético animal y vegetal. En ellos, el uso de estas técnicas facilita el proceso de prospección, evaluación, selección y usufructo de la variabilidad genética disponible en una especie de interés para la Humanidad. De esta manera, se reducen significativamente los costos, tiempos y espacios requeridos por los programas de mejoramiento, y se minimiza la incertidumbre inherente a las técnicas convencionales. En esta era, en la que la generación de datos de variados tipos constituye una actividad rutinaria y lleva a la construcción de bases de alta dimensionalidad, la aplicación de herramientas bioinformáticas se torna indispensable para el abordaje preciso de cualquier proceso biológico. La Bioinformática es una disciplina científica emergente que utiliza tecnología de la información para distribuir, organizar y analizar información biológica. Involucra la solución de problemas biológicos complejos usando herramientas de sistemas y computación. En este espacio se presentarán ejemplos de aplicaciones bioinformáticas en programas de mejoramiento genético vegetal y animal, así como la carrera de postgrado Especialización en Bioinformática, única en esta área de vacancia que cuenta con egresados en el presente.
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