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Phean-o-pas, Srivilai,Punteeranurak, Pornpimon,Buaboocha, Teerapong Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.4
$Ca^{2+}$/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 stress induced expression of OsCam1 gene requires the $[Ca^{2+}]_{cyt}$ elevation that is known to occur in response to these stimuli.
The Role of the OsCam1-1 Salt Stress Sensor in ABA Accumulation and Salt Tolerance in Rice
Sukhumaporn Saeng-ngam,Warintra Takpirom,Teerapong Buaboocha,Supachitra Chadchawan 한국식물학회 2012 Journal of Plant Biology Vol.55 No.3
Involvement of the salt-inducible calmodulin gene,OsCam1-1, in abscisic acid (ABA) biosynthesis during salt stress was studied in the ‘Khoa Dawk Mali 105’ (KDML105)rice cultivar (Oryza sativa L.). FL530-IL, an isogenic saltresistant line derived from the KDML105 cultivar, accumulated a 2.9-fold higher concentration of ABA in the leaves after salt stress treatment than that for KDML105. A twenty-four and a seven- fold higher level of OsCam1-1 transcripts were detected in the leaves of the FL530-IL and KDML105 rice cultivars, respectively, after 30 min of salt stress compared to non-salt-stressed plants. Transgenic rice lines that constitutively over-express the OsCam1-1 gene were found to up-regulate ABA aldehyde oxidase and 9-cis-epoxycarotenoid dioxygenase 3, two genes involved in ABA biosynthesis, and to have a higher ABA content, when compared to the wild type and the control transgenic lines without OsCam1-1 over-expression. In addition, transgenic plants over-expressing OsCam1-1 were more tolerant to salt stress, with, for example, a better ability to maintain their shoot and root mass (as dry weight) during salt stress, than the control plants. These data indicate that OsCam1-1 signaling is likely to play an important role in ABA biosynthesis, and the level of OsCam1-1 gene expression and ABA accumulation probably contribute to salt resistance in rice.