Abstract
The calmodulin binding transcription activator (CAMTA) is a transcription factor that is widely present in eukaryotes with conserved structure. It contributes to the response to biotic and abiotic stresses and promotes the growth and development of plants. Although previous studies have investigated the number and function of CAMTAs in some species, there is still a lack of comprehensive understanding of the evolutionary process, phylogenetic relationship, expression patterns, and functions of CAMTAs in plants. Here we identified 465 CMATA genes from 112 plants and systematically studied the origin of CAMTA family, gene expansion, functional differentiation, gene structure, and conservative motif distribution. Based on these analyses, we presented the evidence that CAMTA family was originated from chlorophyta, and we speculated that CAMTA might experience obvious structure variation during its early evolution, and that the number of CAMTA genes might gradually increase in higher plants. To reveal potential functions of CAMTA genes, we analyzed the expression patterns of 12 representative species and found significant species specificity, tissue specificity, and developmental stage specificity of CAMTAs. The results also indicated that the CAMTA genes might promote the maturation and senescence. The expression levels and regulatory networks of CAMTAs revealed that CAMTAs could enhance cold tolerance of rice by regulating carbohydrate metabolism-related genes to accumulate carbohydrates or by modulating target genes together with other transcription factors. Our study provides an insight into the molecular evolution of CAMTA family and lays a foundation for further study of related biological functions.
Highlights
The divalent ion of calcium (Ca2+) is an ubiquitous second messenger in eukaryotes (Galon et al, 2010b), and it plays an important role in the growth and development of plants under biotic and abiotic stress (Kudla et al, 2010; Reddy et al, 2011)
The homologous sequences of calmodulin binding transcription activator (CAMTA) genes were retrieved from the constructed local database using BLASTP with protein sequences of six Arabidopsis CAMTA genes as queries
The results showed that 390 CAMTA proteins were located in the nucleus, accounting for 83.87% of all the sequences; 38 CAMTAs were located in the cytosol, accounting for 8.17%; 25 CAMTAs were located in chloroplast, accounting for 5.37%
Summary
The divalent ion of calcium (Ca2+) is an ubiquitous second messenger in eukaryotes (Galon et al, 2010b), and it plays an important role in the growth and development of plants under biotic and abiotic stress (Kudla et al, 2010; Reddy et al, 2011). At least 90 transcription factors have been identified as CaM-binding proteins such as CAMTA, MYB, WRKY, NAC, bZIP, and MADS-box proteins (Reddy et al, 2002; Popescu et al, 2007; Kim et al, 2009; Galon et al, 2010b). Among these transcription factors, the calmodulinbinding transcription activator (CAMTA) is a conserved family and the most characteristic transcription factor related to calmodulin (Bouché et al, 2005; Finkler et al, 2007). The CaMB domain and a varying number of IQ motifs (IQXXXRGXXXR) bind to CaM in a calcium-dependent or calcium-independent manner, respectively (da Costa e Silva, 1994; Aravind and Koonin, 1999; Bork et al, 1999; Song et al, 2006)
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