Cloning and expression analysis for xanthine dehydrogenase gene OsXDH in rice

ObjectiveIn the paper,xanthine dehydrogenase(XDH)gene(OsXDH)was cloned from rice genome and its basic biological information and expression characteristics was analyzed to provide theoretical basis for further study on the mechanism of XDH in regulating rice growth and responding to adversity stress.MethodOryza sativa L.spp.ja-ponica cv.Nipponbare was used as material.Gene OsXDH was cloned from rice genome by homologous cloning.Its ami-no acid sequence was analyzed by bioinformatics.Expression specificity of gene OsXDH and its expression under adversi-ty stress were studied by real-time fluorescent quantitative PCR(qPCR).The expression levels of OsXDH,XDH activity, and chlorophyll content in flag leaf of different transgenic lines at milk-ripe stage were studied.ResultThe sequence of open reading frame(ORF)of gene OsXDH was cloned(GenBank accession No.:LOC4333171). It was 4110 bp in length,encoding 1369 amino acids.The molecular weight of OsXDH protein was about 150.23 kD,with a theoretical iso-electric point(pI)of 6.54.The similarity of protein XDH amino acid sequences with Aegilops tauschhhii,Sorghum bico-lor,Zea mays,Setaria italica,and Brassica napus were 84.54%,84.07%,81.52%,76.35% and 69.22% respectively.Ami-no acid sequence of XDH protein was highly conservative.OsXDH expressed in all tissues of rice,and the expression at pustulation stage was significantly higher than seedling stage and tillering stage(P<0.05).The expression of gene OsXDH could be highly induced by the stresses of drought,darkness,high temperature and salt.Furthermore,XDH activity and leaf chlorophyll content in flag leaf of OsXDH over-expression transgenetic lines at milk ripe stage were higher than wild type,but XDH activity and leaf chlorophyll content in OsXDH interference transgenetic lines were lower than wild type.ConclusionThe expression of gene OsXDH is induced by rice growth and adversity stress factors.It is inferred that OsX-DH is a crucial gene in rice for regulating grow and responding to adverse environment.