Calcium signaling-mediated and differential induction of calmodulin gene expression by stress in Oryza sativa L.
Ca(2+)/calmodulin transduction pathways have been implicated in mediating stress response and tolerance in plants. Here, three genes encoding calmodulin (Cam) members of the EF-hand family of Ca(2+)-binding proteins were identified from Oryza sativa L. databases. Complementary DNA for each of the calmodulin genes, OsCam1, OsCam2, and OsCam3 were sequenced. OsCam1 and OsCam2 encode a conventional 148-amino acid calmodulin protein that contains four characteristic Ca(2+)-binding motifs. OsCam3 encode a similar protein with a 38-amino-acid extension containing a putative prenylation site (CVIL) at the carboxyl terminus. RT-PCR showed that each of the genes is expressed in leaves and roots of 2-week old rice seedlings. By RNA gel blot analysis, OsCam1 mRNA levels strongly increased in response to NaCl, mannitol and wounding treatments. In contrast, OsCam2 mRNA levels were relatively unchanged under all conditions investigated. NaCl treatment and wounding also increased the OsCam3 mRNA level, but in a more transient manner. Our results indicate that although the expression of genes encoding different calmodulin isoforms is ubiquitous, they are differentially regulated by various stress signals. In addition, we have demonstrated that the calcium-channel blocker lanthanum chloride inhibited the induction of OsCam1 gene expression by both NaCl and mannitol treatments. These results suggest that osmotic stressinduced expression of OsCam1 gene requires the [Ca(2+)]cyt elevation that is known to occur in response to these stimuli.
Phean-O-Pas
Srivilai
S
Department of Biochemistry, Faculty of Science, Chulalongkorn University, Payathai Road, Patumwan, Bangkok 10330, Thailand.
Punteeranurak
Pornpimon
P
Buaboocha
Teerapong
T
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000502:physiology*; D007811:Lanthanum / Q000494:pharmacology; D008969:Molecular Sequence Data; D012275:Oryza / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D017368:Protein Prenylation; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology; D013314:Stress, Mechanical
D002147:Calmodulin; D018076:DNA, Complementary; D012333:RNA, Messenger; C028521:lanthanum chloride; D012965:Sodium Chloride; D007811:Lanthanum; D002118:Calcium