ARTICLE 1 - research
A MULTIVARIATE APPROACH TO EXPLORE THE GENETIC VARIABILITY IN THE F2 SEGREGATING POPULATION OF A TOMATO SECOND CYCLE HYBRID
VARIABILIDAD EN LA POBLACIÓN F2 SEGREGANTE DE UN HÍBRIDO DE TOMATE DE SEGUNDO CICLO
Cabodevila V.G., Picardi L.A., Pratta G.R.
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.
Key words:plant breeding, plant genetic resources, fruit quality, AFLP, multivariate analysis
ARTÍCLE 2 - research
YIELD PREDICTION IN CORN HYBRIDS (Zea mays L.) IN LATE SOWING ENVIRONMENTS
PREDICCIÓN DEL RENDIMIENTO DE HÍBRIDOS DE MAÍZ (Zea mays L.) EN AMBIENTES DE SIEMBRA TARDÍA
Biasutti C.A., Balzarini M.B.
Accurate prediction of the phenotypical performance of untested single-cross hybrids allows for a faster genetic progress of the breeding pool at a reduced cost. Yield data of maize hybrids were employed to predict the performance of new untested hybrids in late sowing environments. Different groups of predictor hybrids were formed using both data from high and low relatedness between predictors and predicted hybrids and by employing data from low and high yielding environments. A new group of hybrids were formed and evaluated in field trials to validate the predictions. The effectiveness of the predictions was investigated by means of the correlation coefficient between predicted and observed yield values. The best predictions of untested new hybrids were reached by using maximum relatedness information combined with data obtained in the best yielding environments.
Key words: maize, relationship, yield, BLUP
ARTÍCLE 3 - research
CHARACTERIZATION OF GENETIC VARIABILITY IN MELILOTUS ALBUS GERMPLASM BY ISSR AND SSR MOLECULAR MARKERS
CARACTERIZACIÓN DE LA VARIABILIDAD GENÉTICA EN GERMOPLASMA DE MELILOTUS ALBUS MEDIANTE MARCADORES MOLECULARES ISSR Y SSR
Tomas P.A., Rivero M.N., Tomás M.A.
Melilotus albus is a legume plant naturalized in Argentina with a great potential to be used as a forage resource in restricted environments. Our objective was to characterize 10 accessions of M. albus belonging to a collection from INTA and from the FCA-UNL by using molecular markers. Five ISSR primers producing 52 bands, 90 % of them polymorphic, were found to be equally informative. Eight SSR loci were amplified generating 30 alleles, averaging 3.8 alleles per locus, almost all of them highly informative. In numerical analysis, separation among accessions was unclear; genotypes congregate in complex intermixed groups. The greatest proportion of the variation was registered within accessions, in accordance with the allogamous reproductive nature of the species. Since neutral markers were used, the high variability encountered within accessions could be related to gene flow among them and/or a similar origin of the introduced materials. Results from this study support the fact that ISSR and SSR markers provide complementary information and that they are valuable and effective tools to be used to characterize the available germplasm of the species, although other markers such as the functional ones are recommended to better understand the variability in the species and its use in breeding programs.
Key words: Melilotus, genetic diversity, microsatellite, forage
ARTÍCLE 4 - research
SEROTONERGIC POLYMORPHISMS: ALLELIC AND GENOTYPIC FREQUENCY DISTRIBUTION IN THE MAR DEL PLATA, ARGENTINA, POPULATION AND COMPARISON OF GENOTYPING METHODS
POLIMORFISMOS SEROTONINÉRGICOS: DISTRIBUCIÓN DE FRECUENCIAS ALÉLICAS Y GENOTÍPICAS EN LA POBLACIÓN DE MAR DEL PLATA, ARGENTINA Y COMPARACIÓN DE MÉTODOS DE GENOTIPADO
Perez Maturo J., Videla Y., Di Gerónimo V., Quintana S.
There are variable responses to Serotonin Selective Reuptake Inhibitors (SSRIs) among patients treated with this medication. Polymorphisms found in the genes coding for the serotonin transporter (5-HTT) and the serotonin 2A receptor (5-HTR2A) can be used as genetic biomarkers capable of predicting treatment efficacy. The SLC6A4 gene has two polymorphisms: 5-HTTLPR, consisting of an insertion/deletion of 44 bp, and 5-HTTVNTR, characterized by 9, 10 or 12 copies of a region of 16-17 bp. Gene 5-HTR2A presents the 1438 G/A SNP. In order to obtain the allelic and genotypic frequencies of the listed polymorphisms in a sample of the Mar del Plata city population, Argentina; PCR and PCR-RFLP methodologies were applied to genotype the 5-HTTLPR and 5-HTTVNTR polymorphisms and the 1438 G/A SNP in 384 unrelated individuals. Different primers for genotyping were compared. The allelic and genotypic frequencies obtained for polymorphism were the following: 5-HTTLPR polymorphism L/L: 18 %; L/S: 61 %; S/S: 21 % (Freq allelic L: 49 %; S: 51 %) and the 5-HTTVNTR 12/12: 42 %, 12/10: 41 %; 10/10: 17 % (Freq Allelic 10: 37.5 %; 12: 62.5 %). For polymorphism 1438 G/A GA: 47 % GG: 36 %, AA: 17 % (Freq allelic G: 59.5 %; A: 40.5 %). This study will provide useful data for investigations that require the use of these polymorphisms as genetic markers linked to the response to psychoactive drugs in our population.
Key words: serotonergic polymorphisms, population frequencies for depression, pharmacogenetics
Dra. TERESA E. CIACCI ANGELERI DE NEGROTTI (Tita)