Nowadays, increments in tomato yield seem to have reached a plateau. Tomato genebank collections have been recognized as a novel source for yield increments. The use of the diversity in Latin America for novel improved varieties is limited by the knowledge gap regarding field-grown tomatoes. As yield has complex, unresolved trade-offs, agromorphological traits become useful for further improvement. In this study, the development of successive clusters was studied in twenty-four Chilean tomato landraces to elucidate the relationships among agromorphological traits of flowers, inflorescences, and fruits. Plants yielded an average of 3297 g m−2, with a variation coefficient of 0.44. Correlation analyses were performed to evaluate the relationships between yield components and plant phenology. Findings suggested a two-level compensation between average fresh fruit weight and the number of fruits, one on a plant basis and the second on a cluster basis. All traits evaluated had significant phenotypic correlations with yield traits. Growing degree days for a cluster to develop had a low negative phenotypic correlation with yield (−0.33***) and a high genetic correlation with the number of clusters (−0.90***). The number of set flowers, as opposed to the number of flowers, was significantly correlated with average fresh fruit weight (−0.17***), supporting the initiation of the trade-off after the fruit set. This study provides new insight into the plant agromorphology of indeterminate plants. In a global climate change context, further study of trade-off relationships is important for identifying genotypes able to sustain their productivity.
Japanese plum (Prunus salicina L.) is a fruit tree of the Rosaceae family, which is an economically important stone fruit around the world. Currently, Japanese plum breeding programs combine traditional breeding and plant physiology strategies with genetic and genomic analysis. In order to understand the flavonoid pathway regulation and to develop molecular markers associated to the fuit skin color (EST-SSRs), we performed a next generation sequencing based on Illumina Hiseq2000 platform. A total of 22.4 GB and 21 GB raw data were obtained from 'Lamoon' and 'Angeleno' respectively, corresponding to 85,404,726 raw reads to 'Lamoon' and 79,781,666 to 'Angeleno'. A total of 139,775,975 reads were filtered after removing low-quality reads and trimming the adapter sequences. De novo transcriptome assembly was performed using CLC Genome Workbench software and a total of 54,584 unique contigs were generated, with an N50 of 1343 base pair (bp) and a mean length of 829 bp. This work contributed with a specific Japanese plum skin transcriptome, providing two libraries of contrasting fruit skin color phenotype (yellow and red) and increasing substantially the GB of raw data available until now for this specie.
Bunch compactness (BC) is a complex, multi-trait characteristic that has been studied mostly in the context of wine grapes, with table grapes being scarcely considered. As these groups have marked phenotypic and genetic differences, including BC, the study of this trait is reported here using a genetically diverse collection of 116 Vitis vinifera L. cultivars and lines enriched for table grapes over two seasons. For this, 3D scanning-based morphological data were combined with ground measurements of 14 BC-related traits, observing high correlations among both approaches (R2 > 0.90–0.97). The multivariate analysis suggests that the attributes ‘berries per bunch’, ‘berry weight and width’, and ‘bunch weight and length’ could be considered as the main descriptors for BC, optimizing evaluation times. Then, GWASs based on a set of 70,335 SNPs revealed that GBS analysis in this same population enabled the detection of several SNPs associated with different sub-traits, with a locus for ‘berries per bunch’ in chromosome (chr) 18 being the most prominent. Enrichment analysis of significant and frequent SNPs found simultaneously in several traits and seasons revealed the over-representation of discrete functions such as alpha-linolenic acid metabolism and glycan degradation. In summary, the utility of 3D automated phenotyping was validated for table grape backgrounds, and new SNPs and candidate genes associated with the BC trait were detected. The latter could eventually become a selection tool for grapevine breeding programs.
10 May 2016 in Plant Genetic Resources: Characterization and Utilization
Choclero is a Chilean traditional floury maize, consumed as a vegetable, with large economic and cultural value due to its culinary properties that give unique characteristics to the traditional local cuisine. Market diversification demands new materials with different ear and kernel characteristics, which are at present not fulfilled by breeders due to lack of genetic diversity. At present, the Instituto de Investigaciones Agropecuarias has a Choclero germplasm collection composed of 96 accessions, which can supply this lack of diversity, or increase the gene pool. In the present study, 34 selected Chilean Choclero landraces were characterized for 41 agromorphological traits. Phenotypic evaluation in three environments representative of the core production area revealed significant genetic variability for most of the evaluated traits, leading to the identification of several promising accessions. The greater contribution of genotype in most phenological plant, ear and kernel traits suggest their potential usefulness for breeding purposes. Principal component analysis explained over 75% of the total variation for 29 quantitative agromorphological traits. Cluster analysis separated accessions into four major groups, differentiated mainly by plant phenology and ear trait. These findings indicate a number of useful traits at an intra-racial level and a wide range of phenotypic variation that provides a good source of diversity for use in the development of new Choclero varieties.
Landraces constitute a valuable genetic pool of increased diversity that can be exploited for agriculture sustainability, food security, food quality, and future yield increments. It also contributes to understanding a species’ origin, domestication, population dynamics, and diversity. Chilean tomato germplasm characterization and documentation are scarce. To elucidate its potential and distinctiveness, we assessed the genetic variability between and within accessions of tomato landraces grown in Chile between 1938 and 2016, determining the relationships between them and with some European and US heirloom varieties. For this purpose, the tomato plants were characterized using 72 descriptors for vegetative and reproductive morphology. In addition, molecular diversity and the determination of genetic patterns between tomato accessions were made using highly informative SSR markers. Our results indicate that the genetic structure among evaluated accessions is associated with differences between the Chilean landraces grown to 1938 and cultivars grown in Europe and USA. The Chilean cluster presented a high variability. The Limachino tomato landrace is close to Marmande but distinguishable on phenotype and the molecular basis for its private alleles, being grown in the territory of Limache before 1960 until the present day. Accessions of pink beefsteak tomato grown in Chile to 2015 are distant to the rest of the tomato accessions on morphotype and close in SSR genotype to the materials grown in Chile in 1938, supporting the hypothesis of a pre-green revolution tomato diversification in Chilean territory. Chilean tomato populations may impact breeding programs due to higher variability in yield components. Our results are consistent with other researchers that have proposed Mesoamerica and the Andes Region as tomatoes’ primary center of diversity.