Cloning and expression of sucrose synthase-1 cDNA from sugarcane

Sucrose synthase (SuSy, EC 2.4.1.13) is a major enzyme of sucrose metabolism in sugarcane (Saccharumspp. hybrids) internodes. Most plants have at least two differentially expressed, nonallelic SuSy genes. A cDNA of the entire coding sequence of sucrose synthase-1 was isolated from total RNA from an elongating sugarcane internode. Primers designed from published sequences of SuSy-1 from maize (Zea mays), wheat (Triticum aestivum) and rice (Oryza sativa) amplified a627-bp product through RT-PCR. This was followed by 5′- and 3′ rapid amplification of cDNA ends (RACE). The cDNA is 2717 bp long. The nucleotide sequence is similar to that of cDNAs for SuSy-1 from maize (91 percnt;), rice (89 percnt;) and barley (87 percnt;). The putative protein is 802 amino acids long, and 97 percnt; identical to the sh1 SuSy protein from maize. An antisense riboprobe of the PCR product detected SuSy-1 transcripts in Northern blots of RNA from immature and mature leaf sheaths, the apex and immature leaf roll, immature and mature internodes, sett roots, and germinating vegetative bud. Expression in mature and immature leaf lamina was slight but detectable. This is the first report of a full-length cDNA of SuSy-1 from sugarcane.