Abstract:Two suppression subtractive hybridization (SSH) libraries of tea plant(Camellia sinensis(L.) O. Kuntze) were constructed using cDNA from the dormant buds and sprouting buds. A cDNA fragment, which was homologous to the 5′-end of actin gene family, was identified from the sprouting bud SSH library. Using one primer designed on the basis of the fragment, its fulllength cDNA sequence was cloned through 3′-rapid amplification of cDNA ends (3′-RACE). The full length of the actin gene, named CsActin1, was 1 470 bp (GenBank accession No. HQ235647) and contained a 1134 bp open reading frame (ORF) encoding a 377 amino acid residues, a 5′-UTR of 100 bp and a 3′-UTR of 236 bp. The deduced protein molecular weight was 41.70 kD and its theoretical isoelectric point was 5.31. It contained the characteristic actin family signature sequence (YVGDEAQs.KRG and WISKgEYDE) and actin-related proteins signature (LLTEApLNPkaNR). Homologous alignment showed that it shared over 80% nucleotide sequence similarity and over 95% amino acid sequences similarity with actins in other plants. The phylogenetic tree reconstructed on the basis of amino acid sequences suggested that the relationship between C.sinensis and Populus trichocarpa is the most intimate.