ISOLATION AND CHARACTERIZATION OF PARTIAL cDNA OF SUCROSE SYNTHASE PUTATIVE GENE IN PALMYRA PALM (Borassus flabellifer L.)

• Main Author: Selviani Inabuy, Fainmarinat
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/34729
• Institution: Institut Teknologi Bandung

Intensification of biofuel sources is increasingly required in regards to the limited availability of fossil fuel nowadays. Palmyra palm (Borassus flabellifer) has a great potency to be developed as bioethanol source since it has high content of sucrose in its nira. It was observed that nira produced in dry season is sweeter than that produced in rainy season, which is predicted to be influenced by a difference in expression level of sucrose-related genes in those two different seasons. Isolation and characterization of cDNA of SUS gene in B. flabellifer are required prior to study of the gene expression level. Sequence of B. flabellifer SUS gene is currently unavailable in GenBank, thereby pair of primers was designed from highly conserved region of SUS proteins among monocots. A 1866 bp partial cDNA fragment of SUS putative gene has been succesfully isolated from RNA of the young leaves of B. flabellifer. BLASTn and BLASTp aligments showed that either BfSUS cDNA or BfSUS polypeptide has high similarity with SUS cDNA and proteins from diverse plant species with the highest similarity shown by Tulipa gesneriana. The phylogenetic tree showed that SUS protein sequences of monocot species were distinctively grouped and splitted from those of dicot species. The BfSUS was clustered in monocot group, although not specifically grouped with particular monocot species. Nevertheless, B. flabellifer showed nearest genetic distance with Tulipa gesneriana and Oncidium cv.’Goldiana’. Characterization of BfSUS polypeptide using Geneious 4.6.2 showed the presence of sucrose synthase (SUS) and glycosyl transferase (GT) domains, four putative UDP-glucose binding pockets within the GT domain, and a calcium-dependent Ser/Thr protein kinase binding site, Ser170, within the SUS domain. These domains and motifs are highly conserved in SUS proteins across plant species, confirming that the BfSUS gene fragment obtained in this study is the gene that encodes sucrose synthase in B. flabellifer.