Cloning and Expression Analysis of A Soluble Acid Invertase Gene(SoSAI1) of Sugarcane

【Objective】 The objective of this study is to clone the soluble acid invertase gene(SoSAI1) and 5' promoter sequence from sugarcane, to analyze its sequence and expression patterns. 【Method】 The full-length cDNA sequence of SoSAI1 gene was amplified from the leaves of sugarcane by the technology of rapid amplification of cDNA ends(RACE). The cDNA sequence and the deduced amino acid sequence were analyzed by bioinformatics method. The promoter sequence of SoSAI1 gene was cloned by genome walking. The spatial-specific expressions of SoSAI1 were determined by real-time fluorescent quantitative PCR(qRT-PCR) in leaves and stems at different growth stages of sugarcane, and in roots and leaves under treatment of PEG6000, 100 mmol·L-1NaCl or 6℃ stress conditions. 【Result】 The cloned full length of SoSAI1 cDNA sequence was 2 387 bp, containing a 2 055 bp open reading frame(ORF) which encodes 685 amino acids with a theoretical molecular mass of 74.44 kD. The 5' promoter sequence length DNA sequence was 417 bp, which contained endosperm specific expression of cis-acting elements and participate in the drought induced MYB binding sites. The result of real time PCR exhibited that SoSAI1 was the highest abundance in inflorescence and the lowest in old and matured internodes of stems. The conditions of 15% PEG or 6℃ could induce the expression of SoSAI1 gene in leaves, while 15% PEG or NaCl could induce the expression of SoSAI1 gene in roots. 【Conclusion】 The full length of SoSAI1 and part of the promoter were cloned from sugarcane. The analysis by qRT-PCR suggested that SoSAI1 played an important role in sugarcane for growth and development, sucrose accumulation and response to environmental stress.