Salinity is a major concern in agriculture since it adversely affects plant growth,
development, and yield. Domestication of crops exerted strong selective pressure and
reduced their genetic diversity. Meanwhile, wild species continued to adapt to their
environment becoming valuable sources of genetic variation, with the potential for
enhancing modern crops performance in today’s changing climate. Some wild species are
found in highly saline environments; remarkable examples are the endemic wild
tomatoes from the Galapagos Islands, forming the Solanum cheesmaniae and Solanum
galapagense species (hereafter termed Galapagos tomatoes). These wild tomatoes
adapted to thrive in the coastal regions of the Galapagos Islands.
The present work includes a thorough characterization of a collection of 67 accessions of
Galapagos tomatoes obtained from the Tomato Genetics Resource Center (TGRC).
Genotyping-by-sequencing (GBS) was performed to establish the population structure
and genetic distance within the germplasm collection. Both species were genetically
differentiated, and a substructure was found in S. cheesmaniae dividing the accessions in
two groups based on their origin: eastern and western islands. Phenotypic studies were performed at the seedling stage, subjecting seedlings to 200 mM
NaCl for 10 days. Various traits were recorded and analysed for their contribution to
salinity tolerance, compared to control conditions. Large natural variation was found
across the collection in terms of salt stress responses and different possible salt tolerant
mechanisms were identified. Six accessions were selected for further work, based on their
good performance under salinity. This experiment included scoring several plant growth
and yield-related traits, as well as RNA sequencing (RNAseq) at the fruit-ripening stage,
under three different NaCl concentrations. Accession LA0421 showed an increased yield
of almost 50% in mild salinity (150 mM NaCl) compared to control conditions. The
transcriptome data obtained could reveal the genes involved in the salt stress-related
yield increase. The knowledge obtained so far will be useful for scientists and breeders to select
accessions of interest based on recorded traits. It will allow the use of Galapagos
tomatoes as genetic sources for salinity tolerance traits in commercial tomatoes, thereby
contributing to feed and nourish the growing human population in the years to come.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/626264 |
| Date | 11 1900 |
| Creators | Pailles, Yveline |
| Contributors | Tester, Mark A., Biological and Environmental Sciences and Engineering (BESE) Division, Al-Babili, Salim, McCabe, Matthew, Sinha, Neelima |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
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