CRF (CYTOKININ RESPONSE FACTOR) transcription factors in abiotic-stress and flowering time: from Arabidopsis thaliana to Lactuca sativa and Solanum lycopersicum.

Characterization of CRF (CYTOKININ RESPONSIVE FACTOR) transcription factor family in abiotic-stress response and flowering trait. From Arabidopsis thaliana to Lactuca Sativa and Solanum lycopersicum. The abiotic stresses brought about by climate change, such as drought, floods, alterations in temperature and others, are altering important agronomic traits, such as the flowering time of vegetable species. This can have a negative impact on the abundance and organoleptic properties of the crops. Adaptation to environment involves the accumulation of random mutations that can be fixed if they confer an evolutionary advantage. Genetic biodiversity in natural and domesticated plants populations is the richest source of allelic variants that are "tested" naturally by evolutionary mechanisms, and therefore is the most important resource for genetic improvement. More than 60% of adaptive mutations are associated with polymorphisms in transcription factors (TF) DNA sequences that leads to variations in the way they regulate their target genes in response of environmental and developmental signals. In facts, transcription represents the primary regulation level in determining an organism phenotype starting from his genotype. TF are thus the main target on which the process of adaptation of genotypes to the environment acts. CRFs (CYTOKININ RESPONSIVE FACTOR) are ubiquitous TFs of the plant kingdom and are at central to the hormonal crosstalk between auxins and cytokinins, being induced by cytokinins and being at the same time regulators of auxin transporters (PINs). These TFs play fundamental roles both in plant development and abiotic stress responses and are at the core of the trade-off that takes place between the pathways involved in these traits. In this project, the orthologs of clade III CRFs in the Brassicaceae model species Arabidopsis thaliana (CRF5 and CRF6) will be identified and characterized in the agriculturally relevant species Lactuca sativa (model for the Asteraceae family) and Solanum lycopersicum (model for the Solanaceae family) and the expression of these factors will be profiled in different tissues and conditions by qRT-PCR. Selected transcriptomic data available in public databases such as NCBI’s GEO will be analysed by k-means clustering analysis to identify co-expression modules related to stress response and flowering, to create Gene Coexpression Networks (GCNs), and to compare transcriptional networks between those species. In addition, collections of natural and domesticated varieties of the three species will be explored in silico, in search of mutations "selected" by the evolutionary process, which can confer resistance to the aforementioned stresses. The knowledge developed will be used for the genetic improvement of Lactuca sativa and Solanum lycopersicum, to create molecular markers that can be used to accelerate the breeding of new resilient crops that maintains their productive and organoleptic characteristics in the more variable and extreme environmental conditions that will characterize the upcoming decades.