Phenotypic and Molecular Selection of a Superior Solanum pennellii Introgression Sub-Line Suitable for Improving Quality Traits of Cultivated Tomatoes.

Valentino Ruggieri,Roberta Calafiore,Amalia Barone,Maria Manuela Rigano,Fabrizio Olivieri,Antonietta Aliberti

doi:10.3389/fpls.2019.00190

Valentino Ruggieri, Roberta Calafiore + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2019.00190

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Abstract

The Solanum pennellii Introgression Line (IL) population can be exploited to identify favorable alleles that can improve yield and fruit quality traits in commercial tomato varieties. Over the past few years, we have selected ILs that exhibit increased content of antioxidant compounds in the fruit compared to the cultivar M82, which represents the genetic background in which the different wild regions of the S. pennellii ILs were included. Recently, we have identified seven sub-lines of the IL7-3 accumulating different amounts of antioxidants in the ripe fruit. Since the wild region carried on chromosome 7 induces a low fruit production in IL7-3, the first aim of the present work was to evaluate yield performances of the selected sub-lines in three experimental fields located in the South of Italy. Another aim was to confirm in the same lines the high levels of antioxidants and evaluate other fruit quality traits. On red ripe fruit, the levels of soluble solids content, firmness, and ascorbic acid (AsA) were highly variable among the sub-lines grown in three environmental conditions, evidencing a significant genotype by environment interaction for soluble solids and AsA content. Only one sub-line (coded R182) exhibited a significantly higher firmness, even though no differences were observed for this trait between the parental lines M82 and IL7-3. The same sub-line showed significantly higher AsA content compared to M82, thus resembling IL7-3. Even though IL7-3 always exhibited a significantly lower yield, all the sub-lines showed yield variability over the three trials. Interestingly, the sub-line R182, selected for its better performances in terms of fruit quality, in all the trials showed a production comparable to that of the control line M82. A group of species-specific molecular markers was tested on R182 and on the parental genotypes in order to better define the wild genomic regions carried by the elite line R182. In these regions three candidate genes that could increase the level of AsA in the fruit were identified. In the future, the line R182 could be used as pre-breeding material in order to obtain new varieties improved for nutritional traits.

Highlights

Tomato (Solanum lycopersicum L.) is one of the most important and most extensively used crops worldwide and a major component of the Mediterranean diet, even if fruit quality and flavor have deteriorated in recent years (Liu et al, 2016; Rambla et al, 2017)
Plant material consisted of the cultivated genotype M82 (LA3475), the S. pennellii in S. lycopersicum IL7-3, previously selected in our laboratory for high content of ascorbic acid (AsA) in the fruit (Di Matteo et al, 2010), and seven sublines of the region 7-3 previously obtained and characterized as described in Calafiore et al (2016)
Fruit quality and fruit morphology were evaluated in the same lines by measuring eight

Summary

Introduction

Tomato (Solanum lycopersicum L.) is one of the most important and most extensively used crops worldwide and a major component of the Mediterranean diet, even if fruit quality and flavor have deteriorated in recent years (Liu et al, 2016; Rambla et al, 2017). The Solanum pennellii ILs have been broken into additional sublines carrying molecular marker-defined introgressions that are smaller than those carried by the original ILs, further facilitating the identification of candidate genes (Alseekh et al, 2013) These sub-isogenic lines are available to the scientific community and have been recently used to map loci affecting fruit chemical composition (Alseekh et al, 2015; Liu et al, 2016)

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