Abstract: S-adenosyl-L-homocysteine hydrolase (SAHH) is a key enzyme in the regulation of intracellular methylation reactions. Though the SAHH function has already been elucidated in various living creature bodies, it is still not explicit in growth and development of cotton fiber. Therefore, research of SAHH may provide effectively basis to clarify the mechanism of cotton growth and development. In this paper, we obtained a full length cDNA fragment of SAHH in cotton and further finished its expression, mapping and Southern blotting analyses. A cDNA clone encoding S-adenosyl-homocysteine hydrolase (Library No. g073a03a, GhSAHH) was isolated from cotton fiber cDNA library of 7235 germplasm line with elite fiber quality in Gossypium hirsutum L. The length of this cDNA clone was 1 598 bp. Further, a 318 bp-long-upstream fragment was obtained via 5′RACE technique. The full length of the cDNA clone was 1 916 bp with its open reading frame encoded 485 amino acids. The putative protein of this gene had an isoelectric point of 5.69 and a calculated molecular weight of 53.2 kD. Judging from its expression characters, GhSAHH is expressed in cotton cells, especially in root, hypocotyl and at early stage of fiber developmental period. Southern blotting analyses showed there was only one copy of GhSAHH in the genome of upland cotton. Using the BC1 mapping popula-tion with 140 individuals derived from the hybridization between the upland cotton standard line TM-1 and the sea-island cotton cultivar Hai7124, and TM-1 as recurrent parent, GhSAHH was localized on the chromosome 20. We have already constructed plant express vector and RNAi vector of GhSAHH, the transgenic research on cotton is undertaking.

Key words: Gossypium hirsutum L., Adenosyl-homocysteine hydrolase, Cloning, Expression, Localization