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The "bell pepper" or "chino criollo" tomato is a native Mexican variety with similar characteristics to the "Saladette" tomato and the potential to be used as a source of germplasm to generate commercial hybrids of this type. The aim of this investigation was to identify and select advanced lines with a wide genetic base, derived from crosses between Saladette tomatoes and native populations to generate free pollination varieties and potential parents of Saladette tomato hybrids. The hypothesis was that crosses between native populations and Saladette commercial hybrids generate outstanding offspring. The 103 genotypes evaluated included 10 native parents, three parents derived from commercial hybrids, one commercial hybrid control ("El Cid") and 89 S4 advanced lines. The evaluation was carried out in a greenhouse and hydroponics during the 2020 spring-summer cycle, using a randomized complete block experimental design with three replications and four plants per replication. The total weight and number of fruits were recorded based on the sum of the two cuts performed. The days to flowering of the first cluster, average fruit weight, and total soluble solids were also determined. Analyses of variance were carried out for each variable, as well as orthogonal contrasts and correlations between different combinations of the materials of interest. The comparison of means was carried out using Tukey's test (p £ 0.05). Nine advanced lines with similar or greater characteristics to the control were identified and are recommended to be recombined genetically in a diallelic cross scheme to identify new outstanding offspring. The advanced line 2051 (LOR85 X C) was identified, with a similar yield to that reported for the control, which can be used as an open pollination variety since it has similar characteristics to the control "El Cid", but with native tomato genes. [ABSTRACT FROM AUTHOR]

Objective: To measure the efficiency of using advanced generations of some commercial tomato hybrids for small farmers and to identify the most important yield components associated with yield. Design/Methodology/Approach: Seven saladette-type hybrids of indeterminate growth were evaluated, as well as their respective generations F2s and F3s under greenhouse conditions. The evaluation of the three generations was carried out during the 2013 agricultural cycle. Three harvests were made at 82, 94 and 136 days after transplanting. The experiment was a randomized complete block design, with 4 replications and 10 plants per replication. Results: Results indicated that there were significant differences for a few traits in F2 and F3. Path analysis showed that the total number of fruits had the highest direct and indirect effects on yield through generations. Limitations of the study/implications: The usefulness of advanced generations of tomato commercial hybrids would depend on the genetic background of the parental lines that take part in such as hybrids, as some hybrids would present high inbreeding depression depending on the genetic composition of their progenitors. Findings/Conclusions: Advanced generations of 'LORETO', 'CUAUHTÉMOC' and 'ESPARTACO' could be used by the small growers since low values of inbreeding depression were observed in F2 and F3 families. [ABSTRACT FROM AUTHOR]

Genomic selection is considered to be an important tool in plant breeding programs. However, its application in the earliness of tomato (Solanum lycopersicum L.) has not been studied. The objective of the present study was to evaluate the prediction performance of six statistical models for six quantitative characteristics related to earliness in tomato. The study used phenotypic and genotypic data belonging to an F2 population consisting of 172 tomato plants. Simple sequence repeat (SSR) markers were obtained using genotypic information, and the genomic values were estimated by the following six different statistical models: Bayesian Lasso (BL), Bayesian ridge regression (BRR), BayesA, BayesB, BayesCp, and reproducing kernel Hilbert spaces (RKHS) regression. The correlation values ranged from 0.17 to 0.57. The highest association values were found in days to flowering of the third inflorescence and 1000-seed weight, which were greater than 0.5. In general, all the models performed in a similar manner because only slight differences were observed among the correlation values. Specifically, BL, BayesB, and RKHS exhibited the highest Pearson correlation values for most traits. According to the results, genomic selection could be a useful tool to support tomato breeding focused on earliness. [ABSTRACT FROM AUTHOR]

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Commercial tomato (Solanum lycopersicum L.) hybrids can be a good germplasm for obtaining new tomato inbred lines. The present study was aimed to investigate the stability of commercial F1 hybrids under climatic conditions of highlands, to estimate genetic parameters, and evaluate the breeding potential of F1 hybrids based on the agronomic performance of its F3 progeny. We employed a breeding scheme based on pedigree selection for the obtainment of 49 F3 families. Significant differences were found in most of the traits evaluated in both F1 and F3 generations, while in the F2 population only one variable showed significant differences. Heritability ranged from 0.07 to 0.29 for F1, and from 0.16 to 0.45 for F3. Most of the F1 hybrids exhibited values of stability across seasons in at least one trait. However, 'Loreto' and 'Reserva' only exhibited a high stability for yield. Genetic gains ranged from -8.40 to 72.95. Yield per plant was the traits with the highest gain. Based on genetic gains obtained by the F3 progeny, we concluded that 'Cid', 'Espartaco' and 'Loreto' have a high breeding potential for yield and other traits, which could be exploited by public tomato breeding programs. [ABSTRACT FROM AUTHOR]

Tomato’s (Solanum lycopersicum L.) narrow genetic background limits its genetic improvement. The tomato genetic base may be broaden with the use of its native and wild populations as they are a source of useful alleles, to increase yield, quality, and resistance to biotic and abiotic factors that cause stress. Native tomato collections from Mexico have a greater genetic diversity than that of elite germplasm; this implies that genotypes with agronomic, morphological and allelic characteristics different from such elite germplasm may be selected. Therefore, our objective was to evaluate the genetic diversity of 26 accessions of native Mexican tomatoes and identify the best ones for their use in tomato breeding. An agromorphological characterization with 20 traits in a completely randomized experimental design with three replications was performed along with a study with molecular SSR markers. The principal components analysis and hierarchical grouping allowed to identifying four groups with outstanding yield, size and internal fruit quality characteristics. The molecular markers were used to calculate the Shannon index, Nei index and Roger genetic distance, from which they generated seven groups, whose inbreeding and fixation coefficients were close to 1. This indicated the presence of inbreeding and wide differences within of the identified groups. With both characterizations and the Gower distance, the separation of S. lycopersicum L. and S. pimpinellifolium L. species was determined. The native Mexican tomato genotypes possess great genetic diversity and allelic variability that would allow their use in different breeding programs to incorporate alleles for yield and yield components, size and sugars content in the cultivated tomatoes. [ABSTRACT FROM AUTHOR]

Selection plays an important role into breeding programs since it increases the population genotypic mean for a trait. In tomato, the generation and evaluation of large populations is an activity carried out by the breeder which produces increases in cost and time. The objective of this research was to compare the accuracy of phenotypic and marker-based selection for six traits related to fruit in a segregating population as well as to study the performance of several models of genomic selection. Results of the evaluation of six quantitative traits indicated that the prediction accuracies using ridge regression and Bayesian LASSO were greater in comparison to that obtained by multiple linear regression for the situations proposed. During the selection of the best genotypes at both F 2 and F 3 generations, in general, the phenotypic selection had higher genetic gains than those obtained by the strategies based on genomic selection and marker assisted selection. [ABSTRACT FROM AUTHOR]

Yield is a complex trait that is affected by several genetic and environmental factors. Yield is defined as the amount of the part of interest that is harvested from a crop plant in a given area. We investigated the genetic basis of yield in an F2 population derived from a cross between Solanum lycopersicum L. and its most closely related wild species S. pimpinellifolium L. We found that average fruit weight, fruit diameter, and fruit length had a strong effect on yield. In addition, small effects on yield due to soluble solids content and locule number were also observed. A total of 25 different significant quantitative trait locus (QTLs) were detected for six traits (fruit length and diameter, fruit weight, yield, locule number, and Brix degrees). The percentage of phenotypic variation associated with single QTLs ranged from 4.19% to 12.67%. A strong co-location of QTLs among yield and fruit size traits was observed, suggesting that these QTLs play a role in the same expression process controlling yield. We also realized that the effects of soluble solids content on yield could be due to direct effects of fruit size QTLs linked to genes controlling soluble solids content. This result then may suggest that yield in tomato is mainly formed by fruit size QTLs, whereas the remaining factors may play a complementary role in the expression of tomato yield. [ABSTRACT FROM AUTHOR]

General (GCA) and specific (SCA) combining ability are parameters that provide insight into the genetic value of lines utilized in plant breeding programs based on hybridization. The aim of this study was to estimate the GCA for yield of ten S 5 lines derived from Mexican tomato landraces and four testers S 5 derived from commercial varieties, as well as to estimate the SCA of forty hybrids obtained under the line × tester mating design. The traits evaluated were fruit yield and six of its yield components. The lines with the greater GCA effects for yield were LOR82, LOR91 and LOR111, with values of 240, 208, and 99, respectively, being higher than those obtained by most of the testers, which suggested that those native lines have important alleles. In the highest-yielding crosses participated at least one line with high positive GCA effects. In contrast, in crosses with the lowest yield, at least one parent or both exhibited negative GCA. All this results indicated that the best or worst hybrids are not necessary obtained from parents having a high or low GCA, respectively. Valuable germplasm with high yield potential was identified to be used in the generation of hybrid or open-pollinated varieties in tomato breeding programs. [ABSTRACT FROM AUTHOR]