Cloning of Choline Monooxygenase Gene from Haloxylon ammodendron and Construction of Its Plant Expression Vector

Through RT-PCR(reverse transcription polymerase chain reaction) and RACE(rapid amplification of cDNA ends),a 1 344 bp fragment containing entire choline monooxygenase(CMO) coding region of 447 amino acids(aa) has been obtained(as named HaCMO) from extreme xerophyte and salt-tolerant plant Haloxylon ammodendron.Plant expression vector pCAMBIA2300-HaCMO with obtained fragment was constructed.Nucleotide sequence of HaCMO was similar to the corresponding fragment of CMO cDNA of several other plants,such as Spinacia oleracea,Atriplex hortensis,Suaeda liaotungensis,Salicornia europaea,Beta vulgaris,with a similarity of more than 74.5%.Encoded protein by HaCMO and CMO protein from above mentioned plants also shared more than 73.5% identity at the amino acid level.The result showed CMO gene was conserved in Chenopodiaceae.The study provided material for further exploring drought resistant and salt tolerant mechanisms of H.ammodendron in molecular level,and laid a foundation for finding and exploitation of resistant genes from stress-tolerant plants.