Diverse Traits Contribute to Salinity Tolerance of Wild Tomato Seedlings from the Galapagos Islands

Abstract

Traits of modern crops have been heavily selected in agriculture, leaving commercial lines often more susceptible to harsh conditions compared with their wild relatives. Understanding the mechanisms of stress tolerance in wild relatives can enhance crop performance under stress conditions such as high salinity. In this study, we investigated salinity tolerance of two species of wild tomato endemic to the Galapagos Islands, Solanum cheesmaniae and Solanum galapagense. Since these tomatoes grow well despite being constantly splashed with seawater, they represent a valuable genetic resource for improving salinity tolerance in commercial tomatoes. To explore their potential, we recorded over 20 traits reflecting plant growth, physiology, and ion content in 67 accessions and two commercial tomato lines of Solanum lycopersicum. Salt treatments were applied for 10 d using supported hydroponics. The Galapagos tomatoes displayed greater tolerance to salt stress than the commercial lines and showed substantial natural variation in their responses. The accessions LA0317, LA1449, and LA1403 showed particularly high salinity tolerance based on growth under salinity stress. Therefore, Galapagos tomatoes should be further explored to identify the genes underlying their high tolerance and be used as a resource for increasing the salinity tolerance of commercial tomatoes. The generated data, along with useful analysis tools, have been packaged and made publicly available via an interactive online application (https://mmjulkowska.shinyapps.io/La_isla_de_tomato/) to facilitate trait selection and the use of Galapagos tomatoes for the development of salt-tolerant commercial tomatoes.

Natural variations in SlSOS1 contribute to the loss of salt tolerance during tomato domestication

“…Tomato ( Solanum lycopersicum ) is one of the most consumed fruit and vegetable crops in the world (Zhu et al ., 2018). The wild ancestor of tomato is adapted to highly saline coastal habitats, while cultivated varieties have lost salt tolerance during domestication for larger fruit (Pailles et al ., 2020). By using a genome‐wide association approach, we recently identified genetic variations in the Na + –K + transporter SlHAK20 responsible for the variations in root Na + /K + ratio and the loss of salt tolerance during tomato domestication (Wang et al ., 2020).…”

A Review on the Beneficial Role of Silicon against Salinity in Non-Accumulator Crops: Tomato as a Model

“…Landraces, as well as ancient and wild varieties are valuable resources for breeding programs [ 58 , 59 , 60 , 61 , 62 ]. For example, wild relatives from the Galapagos Islands ( S. cheesmaniae (L. Riley) Fosberg and S. galapagense S.C. Darwin and Peralta) are endemic species adapted to the highly saline coastal areas and a recent screening of 67 accessions revealed that different traits are involved in the high tolerance to salinity [ 62 ].…”

“…Landraces, as well as ancient and wild varieties are valuable resources for breeding programs [ 58 , 59 , 60 , 61 , 62 ]. For example, wild relatives from the Galapagos Islands ( S. cheesmaniae (L. Riley) Fosberg and S. galapagense S.C. Darwin and Peralta) are endemic species adapted to the highly saline coastal areas and a recent screening of 67 accessions revealed that different traits are involved in the high tolerance to salinity [ 62 ]. Tomato landraces from Southern Italy showed higher tolerance to drought via the constitutive increased activities of catalase, ascorbate peroxidase and glucose-6-phosphate dehydrogenase [ 63 ], while in the wild halophyte ( S. chilense ) exposed to NaCl, an increase in ethylene biosynthesis, accompanied by the upregulation of the 1-aminocyclopropane-1-carboxylic acid synthase ( ACCS2 ) gene, was correlated with a high tolerance to salinity [ 64 ].…”

Early Growth Stage Characterization and the Biochemical Responses for Salinity Stress in Tomato

“…The majority of tomato cultivars have the genetic potential to tolerate mild to medium salt stress [ 17 ]. Every plant growth and development stage (seed germination, vegetative and reproductive growth) demonstrate sensitivity to salinity stress, leading to decreased crop performance and yield [ 18 , 19 ]. However, in many crops, studies have revealed that salinity tolerance at the early growth stages is of more importance than at the later plant stages [ 19 , 20 ].…”