Abstract
BackgroundThe SWEET (Sugars will eventually be exported transporters) gene family plays multiple roles in plant physiological activities and development process. It participates in reproductive development and in the process of sugar transport and absorption, plant senescence and stress responses and plant-pathogen interaction. However, thecomprehensive analysis of SWEET genes has not been reported in cotton.ResultsIn this study, we identified 22, 31, 55 and 60 SWEET genes from the sequenced genomes of Gossypium arboreum, G. raimondii, G. hirsutum and G. barbadense, respectively. Phylogenetic tree analysis showed that the SWEET genes could be divided into four groups, which were further classified into 14 sub-clades. Further analysis of chromosomal location, synteny analysis and gene duplication suggested that the orthologs showed a good collinearity and segmental duplication events played a crucial role in the expansion of the family in cotton. Specific MtN3_slv domains were highly conserved between Arabidopsis and cotton by exon-intron organization and motif analysis. In addition, the expression pattern in different tissues indicated that the duplicated genes in cotton might have acquired new functions as a result of sub-functionalization or neo-functionalization. The expression pattern of SWEET genes showed that the different genes were induced by diverse stresses. The identification and functional analysis of SWEET genes in cotton may provide more candidate genes for genetic modification.ConclusionSWEET genes were classified into four clades in cotton. The expression patterns suggested that the duplicated genes might have experienced a functional divergence. This work provides insights into the evolution of SWEET genes and more candidates for specific genetic modification, which will be useful in future research.
Highlights
The SWEET (Sugars will eventually be exported transporters) gene family plays multiple roles in plant physiological activities and development process
Gene identification and conserved domain retrieval The SWEET amino acid sequences reported in Arabidopsis, rice and cucumber were used as query sequences and blasted against sorghum, poplar, maize, cocoa, Gossypium arboreum, G. raimondii, G. hirsutum, and G. barbadense genome database with e-values of 1e-5
The total numbers of SWEET genes identified in the two diploid cotton (G. arboreum and G. raimondii) were lower than that in allotetraploid (G. hirsutum and G. barbadense) cotton (Table 1, Additional file 1: Table S1, Additional file 2: Table S2 and Additional file 3: Table S3)
Summary
The SWEET (Sugars will eventually be exported transporters) gene family plays multiple roles in plant physiological activities and development process. It participates in reproductive development and in the process of sugar transport and absorption, plant senescence and stress responses and plant-pathogen interaction. Sugar cannot be transported independently across the plant cell membrane system and requires the SWEETs are a new family of sugar transporters discovered in recent years, generally with seven transmembrane domains and two MtN3 motifs (Talbot 2010; Baker et al 2012). SWEET shows the function of bidirectional reversible transport of sugar, and promotes the diffusion of sucrose to the apoplast pathway through transmembrane across the gradient of concentration on cell efflux (Baker et al 2012; Lin et al 2014; Eom et al 2015).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
