Identification of fasciclin-like arabinogalactan protein family genes associated with fruit ripening in tomato

Abstract Background: Tomato ( Solanum lycopersicum ) is a model plant for fruit ripening, of which contains a series of complex physiological and biochemical process. Fasciclin-like arabinogalactan proteins (FLAs) are a subclass of arabinogalactan proteins (AGPs) involved in cell wall formation and intracellular signal transduction. However, its functional mechanism in plant development including fruit ripening is rarely studied. In the present study, we identified four species tomatoes’ FLAs and analyzed their structural characteristics, evolutionary history and expression patterns during fruit development to mine candidate genes and determine their potential role in tomato fruit ripening. Results: In the present study, 18 ,21, 22 and 22 FLAs were identified from the S. lycopersicum, S. pimpinellifolium , S. pennellii , and S. lycopersicoides , respectively. These proteins were divided into four groups by evolutionary and structural characteristics, and each group of FLAs in FAS structure domain, glycosylphosphatidylinositol (GPI) and the number there are similarities. The FLAs in four species are relatively conserved, and most of them are distributed at both ends of chromosomes. The FLA family members are amplified and evolved mainly by means of segmental duplication and purifying selection. Similar transcripts and expression patterns analysis among them revealed their regulatory roles in tomato fruit ripening. More intresting, in the WGCNA module constructed by the combination of tomato fruit transcriptome and targeted carotenoid metabolome, several SlFLAs co-expressed with genes enriched in secondary metabolism. Conclusion: The FLAs gene family found in four species tomatoes and provides valid information in their little-studied studies on the regulation of fruit ripening. Combined with the detection of a key metabolite of tomato fruit ripening, carotenoids, which broadens the idea of biological functional analysis of SlFLAs and provides a theoretical basis and candidate genes for improving tomato fruit quality.