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 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.
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.
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.
La producción de banana sobre bases científicas es relativamente nueva en Argentina. Para evaluar la productividad potencial en la provincia de Formosa, se ensayaron cuatro variedades internacionales ...de banana durante cuatro campañas en el campo experimental de la Estación Experimental Agropecuaria de INTA Chaco-Formosa. También se aplicaron datos para determinar el tamaño de parcela óptimo para conferir robustez estadística a los ensayos de campo. Se detectaron diferencias entre variedades y entre campañas, pero su interacción no fue significativa. No obstante, un análisis biplot identificó patrones de rendimientos diferenciales y combinaciones específicas de variedad-campaña. Según el método de la curvatura máxima, el tamaño de la parcela debe incluir de 6 a 8 plantas de cada variedad para una confianza estadística óptima de los ensayos de campo. Sin embargo, dado que la banana es un cultivo perenne y que el medioambiente argentino no es óptimo para su producción, no todas las plantas se cultivan todos los años. Por lo tanto, se propone un número óptimo de 10 plantas para asegurar la confianza estadística en los ensayos de campo de la provincia de Formosa.
Elucidating the determinants of tomato nutritional value and fruit quality to introduce improved varieties on the international market represents a major challenge for crop biotechnology. Different ...strategies can be undertaken to exploit the natural variability of
Solanum
to re-incorporate lost allelic diversity into commercial varieties. One of them is the characterization of selected germplasm for breeding programs. To achieve this goal, 18 RILs (
S. lycopersicum
×
S. pimpinellifolium
) were comprehensively phenotyped for fruit polar metabolites and quality associated traits. Metabolites were quantified by GC–MS and
1
H NMR. Integrative analyses by neuronal clustering and network construction revealed that fruit properties are strongly associated with the metabolites aspartate, serine, glutamate and 2-oxoglutarate. Shelf life and firmness appeared to be linked to malate content. By a comparative analysis of the whole data set, ten RILs presented higher number of traits with positive effect than the
S. lycopersicum
×
S. pimpinellifolium
hybrid. Thus, these lines can be proposed as promising candidates for breeding programs aimed to improve fruit quality.
The aim of this work was to evaluate the components of the genetic mean values and variances of the in vitro culture response in a cross between cultivar 'Caimanta' of the cultivated L. esculentum as ...the high regeneration capacity genotype and accession LA722 of the exotic L. pimpinellifolium as the low regeneration capacity genotype. The callus percentage (C, number of cultures that only produced callus x 100/total number of explants), the regeneration percentage (R, number of cultures that differentiated into completely developed shoots and/or primordial x 100/total number of explants) and the productivity rate (PR, total number of completely developed shoots/total number of cultures) were evaluated 30 days after culture initiation in the parents, F₁, F₂ and backcrosses. The in vitro culture response was controlled by gene action of complete dominance of the cultivated genome over the exotic one. Genetic interaction was not detected in these sets of data. The narrow sense heritability (h²) values were 0 for C and R, and 0.62 for PR. In consequence, genetic variability was mostly non-additive for both callus and regeneration percentages, while it was mostly additive for the productivity rate.
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.
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