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
ABSTRACT
Aim: New species of Plant Growth Promoting Rhizobacteria (PGPR), with varying growth promoting and biocontrol ability are often being discovered. They facilitate plant growth either directly by secreting nutrients and hormones or indirectly by providing defence mechanism to the plant. The present study was undertaken to isolate PGPR from the rhizosphere of Solanum lycopersicum and Arachis hypogaea, and test their growth promoting ability and antifungal activity against Fusarium oxysporum. Methodology: PGPRs were isolated from the rhizosphere of S. lycopersicum and A. hypogaea by serial dilution of the rhizospheric soil and identified by 16s rDNA sequencing. The isolates were analysed for antifungal activity against F. oxysporum, indole 3-acetic acid (IAA) production and phosphate solubilisation. For the growth promotion assay, aseptically grown Vigna radiata seedlings were dipped separately in isolated bacterial suspension of PGPR (109 CFU ml-1) and planted in autoclaved soil. Plants were irrigated with 50% Hoagland solution for every 48 hr and maintained at 25 ± 2 °C with 16/8 hr of light and dark photoperiod. Growth promotion was examined in terms of differences in shoot length, root length, fresh weight and dry weight after 12 days of treatment. Results: Six isolates were found to have antifungal activity towards plant pathogen, F. oxysporum. Five isolates showed similarity to Pseudomonas aeruginosa (B7-1, B11-5, B3-1, Rh-1, Rh-2) and one to Pseudomonas putida (B53). All six strains were able to produce IAA, where B53 and B13-1 showed the highest production compared to other strains. P. putida B53 demonstrated the highest plant growth promotion activity by significantly (p<0.05) increasing the growth of V. radiata plants as evidenced by increase in shoot length, root length, fresh and dry weight. Interpretation: The results obtained from the present study supports that PGPRs like Pseudomonas sp. could serve as potential eco-friendly bio-fertilizer and bio- fungicide