Identification, characterization and expression analysis of sucrose transporters in the model plant Nicotiana tabacum cv.petit havana

ABSTRACT

Aim: Sucrose transporters (SUTs) are transmembrane proteins involved in transport of sucrose along the phloem pathway of plants. Nicotiana tabacum, a well-known model plant has been reported to have three sucrose transporters (NtSUT1, NtSUT3 and NtSUT4), till date. The present study was undertaken to identify new SUTs from its genome and characterize all the NtSUT genes of Nicotiana tabacumMethodology: In the present study, new putative sucrose transporter genes were identified through extensive searches of the draft genome and transcriptome of tobacco using BLAST. In-silico characterization of the SUT gene family (NtSUT1, NtSUT2, NtSUT3, NtSUT4 and NtSUT5) of Nicotiana tabacum was done using bioinformatics tools. Spatial expression analysis was done for NtSUT genes in five different tissues of Nicotiana tabacum cv.petit havana using semi-quantitative RT-PCR. Results: Two new putative sucrose transporters NtSUT2 and NtSUT5 were identified from the publicly available tobacco transcriptome data and characterized using in-silico tools. Multiple sequence alignment of deduced amino acids of all the five SUTs revealed the presence of highly conserved domains and signature histidine residue in the sugar binding motif. Phylogenetic analysis grouped NtSUT1 and 3 into group 2, NtSUT4 and 5 into group 4 and NtSUT2 into group 3. NtSUT1 showed higher expression in leaves and flower while NtSUT2, 3 and 4 were abundant in root and flower. NtSUT5 showed a lower expression in all the tissues. Interpretation: Based on the sequence information and structural similarities, it is clear that the two newly identified putative SUT genes (NtSUT2 and NtSUT5) belonged to the SUT family of tobacco. This comprehensive study provides a consolidated data on characteristic features of SUT family proteins of tobacco