Phenotyping of Tomato for SolCAP and Onward into the Void

Abstract

<jats:p>Standardized phenotyping is being used in tomato (<jats:italic>Solanum lycopersicum</jats:italic>) and potato (<jats:italic>S. tuberosum</jats:italic>) as part of the USDA-funded Solanaceae coordinated agricultural project (SolCAP). In tomato, a panel of 480 lines, 144 fresh market, 144 processing, 44 vintage lines, 48 landraces, and 101 related <jats:italic>Solanum</jats:italic> species accessions, are being grown over two seasons at multiple locations. These tomato genotypes will also be screened for over 7600 single nucleotide polymorphism markers that are being developed. Characters being phenotyped are hypocotyl color, plant habit, inflorescence (simple or compound), flower fasciation, flowering time, time to maturity, size of blossom scar, and pedicel type (jointless or jointed). Transverse and equatorial cross-sections of fruit are also being scanned to obtain measures of fruit shape and color by tomato analyzer computer software. Other fruit characters being measured are pH, titratable acidity, and soluble solids. Some useful information may come from this phenotyping and genotyping effort. However, in this author's opinion, the value of measuring some of the traits is very limited in the face of much more important breeding traits that are difficult to fit into a standardized phenotyping format. For instance, proper assessment of several fruit disorders is not being attempted, but such data might yield some invaluable marker information. Part of this is the result of funding limitations for the phenotyping effort. However, a major benefit of the SolCAP analysis will be the development of markers that will differentiate the lines being studied, because there is a present lack of polymorphisms in tomato germplasm where wild species introgressions are minimal or distant in time. This will allow breeders to proactively select for recurrent parent backgrounds in backcrossing projects and may aid in the identification of associations of markers with important characteristics. As one looks to the future of standardized phenotyping, there are some important traits that will be difficult to phenotype such as tomato flavor, which is quite subjective and for which there are no good objective measures.</jats:p>

Diversidad morfológica de fruto de una colección de tomate (Solanum lycopersicum L.) mediante fenotipado basado en imágenes digitales

“…In addition, it allows a large number of fruit shape and flesh colour traits to be graded. Several studies have been conducted with TA to characterize tomato landraces [10][11][12][13] , and the genetics of fruit shape in this crop [14][15][16][17] . These studies reveal that TA is a powerful tool for accurately describing tomato fruit morphology, thanks to the use of a unique mathematical descriptor associated with a shape attribute.…”

Field Evaluation of CRISPR-Driven Jointless Pedicel Fresh-Market Tomatoes

“…The potential benefits of the jointless pedicel trait are well known, and linked molecular markers for the causative gene of the trait already exist [23]. However, it is difficult to develop jointless pedicel tomato varieties that are as good as existing jointed pedicel tomato varieties because defects such as fruit-cracking, rough blossom scars, and off-shapes, are often more severe in the former under many growth conditions [24]. Because of the challenges associated with the development of jointless pedicel fresh-market tomato varieties using conventional breeding methods, it can be hypothesized that an alternative loss-of-function mutation(s) in the J2 gene (i.e., CRISPR-driven J2 gene-edited mutant) may enable the achievement of a (similar or identical) jointless pedicel phenotype, while bypassing the negative effects on fruit quality.…”

Caracterización, Tipificación, Selección Y Mejora Genética De Variedades Valencianas De Tomate

“…Although molecular markers are of great utility for studying the relationships among local tomato varieties (Terzopoulos and Bebeli 2008), morphological characterization is essential to define the characteristics of local varieties for their protection and registration as recognized conservation varieties (Spataro and Negri 2013;. In this respect, tomato characterization has usually been performed with conventional highly heritable morphological descriptors based on seedling, plant, inflorescence, flower, fruit, and agronomic traits , Scott 2010, UPOV 2013). These descriptors are very useful for description of varieties but have some limitations, especially when characteristics used for establishing cultivar groups in local varieties correspond to subtle differences in fruit morphology (Scott 2010).…”

“…In this respect, tomato characterization has usually been performed with conventional highly heritable morphological descriptors based on seedling, plant, inflorescence, flower, fruit, and agronomic traits , Scott 2010, UPOV 2013). These descriptors are very useful for description of varieties but have some limitations, especially when characteristics used for establishing cultivar groups in local varieties correspond to subtle differences in fruit morphology (Scott 2010). In these cases, conventional descriptors may need to be complemented with more precise characterization tools.…”

“…Tomato Analyzer allows scoring a large number of fruit shape and flesh colour traits from scanned images of fruit sections. Several studies have been performed with Tomato Analyzer to characterize local tomato varieties , Scott 2010) as well as to study the genetics of fruit shape in this crop (Brewer et al 2007, Gonzalo et al 2009.…”