A variação genética natural é uma fonte rica em novos genes e alelos presentes nas espécies selvagens relacionadas às espécies cultivadas. O gênero Solanum seção Lycopersicum possui espécies que evoluíram em variados ecossistemas compreendidos na região que vai do sul do Equador até o norte do Chile. Tais espécies podem ser cruzadas com o tomateiro cultivado (Solanum lycopersicum) e vêm sendo exploradas como fonte de resistência a patógenos, a artrópodes e a estresses bióticos; além de possuírem características ligadas à qualidade do fruto, como alto teor de sólidos solúveis e presença de fitonutrientes. No entanto, tais espécies foram pouco exploradas até o momento quanto a variações alélicas afetando a estrutura da planta, como arquitetura de órgãos dos sistemas caulinares e radiculares. S. galapagense, uma espécie endêmica das Ilhas Galápagos, possui características únicas do gênero, como a presença de folhas bastante recortadas e entrenós curtos. As folhas recortadas de S. galapagense já haviam sido previamente ligadas a Petroselinum (Pts), um alelo com expressão aumentada de um gene da família KNOTTED1-LIKE HOMEOBOX (KNOX). O maior recorte foliar causado por Pts deve-se a interferência na via de desenvolvimento do primórdio foliar, através de sua interação com BIPINNATA (BIP), um gene da família BEL1-LIKE HOMEODOMAIN (BELL), para o qual o tomateiro apresenta um alelo perda de função, bip. No presente trabalho é caracterizado o lócus Galapagos dwarf (Gdw), uma variação genética natural oriunda de S. galapagense. Foram utilizadas em estudos comparativos a cultivar Micro-Tom (MT), uma variedade de tomateiro com pequeno porte e ciclo rápido, e isolinhas contendo o lócus Gdw e os alelos Pts, bip. Nestes estudos, verificou-se que embora todos esses alelos afetem a arquitetura foliar em tomateiro, formando folhas mais recortadas, somente Gdw apresentou fenótipo de entrenó curto, característico do parental S. galapagense. Tal característica, além de ter valor no melhoramento para obtenção de plantas compactas, pode ter implicações adaptativas e ecológicas no contexto em que evoluiu S. galapagense. O lócus Gdw foi mapeado no cromossomo 2 de tomateiro, e no futuro, pretendemos clonar o gene GDW. / Natural genetic variation is a rich source of new genes or alleles, harbored in wild relatives of cultivated plants. The genus Solanum section Lycopersicum has members who had evolved in several ecosystems, extending from southern Ecuador through northern Chile. These species can be hybridized with the cultivated tomato (Solanum lycopersicum) and have been exploited to great extent in tomato breeding, as source of resistance or tolerance to pest, diseases and abiotic stresses. Moreover, wild species bear quality fruit traits that can improve solids soluble content and add phytonutrients into cultivated tomato. However, allelic variations affecting plant architecture coming from wild species have been underexplored. S. galapagense, an endemic species from Galápagos Islands, owns unique features, such as highly subdivided leaves and short internodes. The increased-leaf-dissection phenotype of S. galapagense was previously associated with the higher expression of the causative allele Petroselinum (Pts), a member of the KNOTTED1-LIKE HOMEOBOX (KNOX) gene family. Pts affects the development pattern of leaf primordium, increasing leaf dissection through its interaction with BIPINNATA (BIP), a BEL1-LIKE HOMEODOMAIN (BELL) gene. Also, tomato has a BIP knockout allele, which is present in the bip mutant. The present work characterizes the Galapagos dwarf (Gdw) locus, a natural genetic variation from S. galapagense. Comparative analysis were made among Micro-Tom (MT), a S. lycopersicum cultivar with small size and short life cycle, and its near-isogenic lines (NILs) harboring Gdw, Pts and bip alleles. Although we verified that all these alleles affect leaf architecture, leading to more dissected leaves, only Gdw showed short internodes, which is typical from its parental S. galapagense. Besides its worth for the development of compact plants through breeding, such trait could be adaptive and ecologically meaningful in the evolutionary history of S. galapagense. The Gdw locus was mapped on the chromosome 2, and in the future we intent to clone the causative gene GDW.

A variação genética natural é uma fonte rica em novos genes e alelos presentes nas espécies selvagens relacionadas às espécies cultivadas. O gênero Solanum seção Lycopersicum possui espécies que evoluíram em variados ecossistemas compreendidos na região que vai do sul do Equador até o norte do Chile. Tais espécies podem ser cruzadas com o tomateiro cultivado (Solanum lycopersicum) e vêm sendo exploradas como fonte de resistência a patógenos, a artrópodes e a estresses bióticos; além de possuírem características ligadas à qualidade do fruto, como alto teor de sólidos solúveis e presença de fitonutrientes. No entanto, tais espécies foram pouco exploradas até o momento quanto a variações alélicas afetando a estrutura da planta, como arquitetura de órgãos dos sistemas caulinares e radiculares. S. galapagense, uma espécie endêmica das Ilhas Galápagos, possui características únicas do gênero, como a presença de folhas bastante recortadas e entrenós curtos. As folhas recortadas de S. galapagense já haviam sido previamente ligadas a Petroselinum (Pts), um alelo com expressão aumentada de um gene da família KNOTTED1-LIKE HOMEOBOX (KNOX). O maior recorte foliar causado por Pts deve-se a interferência na via de desenvolvimento do primórdio foliar, através de sua interação com BIPINNATA (BIP), um gene da família BEL1-LIKE HOMEODOMAIN (BELL), para o qual o tomateiro apresenta um alelo perda de função, bip. No presente trabalho é caracterizado o lócus Galapagos dwarf (Gdw), uma variação genética natural oriunda de S. galapagense. Foram utilizadas em estudos comparativos a cultivar Micro-Tom (MT), uma variedade de tomateiro com pequeno porte e ciclo rápido, e isolinhas contendo o lócus Gdw e os alelos Pts, bip. Nestes estudos, verificou-se que embora todos esses alelos afetem a arquitetura foliar em tomateiro, formando folhas mais recortadas, somente Gdw apresentou fenótipo de entrenó curto, característico do parental S. galapagense. Tal característica, além de ter valor no melhoramento para obtenção de plantas compactas, pode ter implicações adaptativas e ecológicas no contexto em que evoluiu S. galapagense. O lócus Gdw foi mapeado no cromossomo 2 de tomateiro, e no futuro, pretendemos clonar o gene GDW. / Natural genetic variation is a rich source of new genes or alleles, harbored in wild relatives of cultivated plants. The genus Solanum section Lycopersicum has members who had evolved in several ecosystems, extending from southern Ecuador through northern Chile. These species can be hybridized with the cultivated tomato (Solanum lycopersicum) and have been exploited to great extent in tomato breeding, as source of resistance or tolerance to pest, diseases and abiotic stresses. Moreover, wild species bear quality fruit traits that can improve solids soluble content and add phytonutrients into cultivated tomato. However, allelic variations affecting plant architecture coming from wild species have been underexplored. S. galapagense, an endemic species from Galápagos Islands, owns unique features, such as highly subdivided leaves and short internodes. The increased-leaf-dissection phenotype of S. galapagense was previously associated with the higher expression of the causative allele Petroselinum (Pts), a member of the KNOTTED1-LIKE HOMEOBOX (KNOX) gene family. Pts affects the development pattern of leaf primordium, increasing leaf dissection through its interaction with BIPINNATA (BIP), a BEL1-LIKE HOMEODOMAIN (BELL) gene. Also, tomato has a BIP knockout allele, which is present in the bip mutant. The present work characterizes the Galapagos dwarf (Gdw) locus, a natural genetic variation from S. galapagense. Comparative analysis were made among Micro-Tom (MT), a S. lycopersicum cultivar with small size and short life cycle, and its near-isogenic lines (NILs) harboring Gdw, Pts and bip alleles. Although we verified that all these alleles affect leaf architecture, leading to more dissected leaves, only Gdw showed short internodes, which is typical from its parental S. galapagense. Besides its worth for the development of compact plants through breeding, such trait could be adaptive and ecologically meaningful in the evolutionary history of S. galapagense. The Gdw locus was mapped on the chromosome 2, and in the future we intent to clone the causative gene GDW.

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.

The classical ethyl methanesulfonate (EMS) tomato mutant bushy root (brt) was studied using a homozygous near isogenic line (brtNIL) in the Micro-Tom (MT) genetic background. The mutation has a pleiotropic phenotype comprising slow seedling development, which may be a consequence of a maternally-inherited small seed phenotype, and a more compact, smaller but not bushier, root phenotype. The number of lateral roots, total root length and taproot size are all smaller in brtNIL than the WT. The BRT locus was mapped to a 137 kbp region containing 9 candidate genes on chr 12; an InDel in the promoter region of Solyc12g014590 – containing two highly conserved pirin domains (Pirin_C and Pirin), was detected. Different expression patterns were confirmed by transcriptomic results, supporting Solyc12g014590 as the gene responsible for the brt phenotype. A naturally occurring recessive mutant named bifuricate (bif) shows an increase in inflorescence (truss) branching in comparison to the wild type (WT) control line, LAM183. In addition, the number of flowers per truss was 235% higher in bif plants than WT. Low temperature is known to increase truss branching, and so a four day low temperature treatment was applied and it was demonstrated that flowering increased significantly more in bif than in LAM183. The BIF locus was mapped to a 2.01 Mbp interval of chromosome 12 containing 53 genes. All coding region polymorphisms in the interval were surveyed, and two genes Solyc12g019420 (a BTB/TAZ transcription factor) and Solyc12g019460 (a MAP kinase) contained one stop codon predicted to disrupt gene function; both genes are excellent candidates for inflorescence branching control based on literature evidence. A newly developed introgression browser was used to demonstrate that the origin of the bif mutant haplotype is Solanum galapagense.

No description available.