RESUMO
Glycine betaine is an important quaternary ammonium compound that is produced in response to several abiotic stresses in many organisms. The synthesis of glycine betaine requires the catalysis of betaine aldehyde dehydrogenase (BADH), which can convert betaine aldehyde into glycine betaine in plants, especially in halotolerant plants. In this study, we isolated the full-length cDNA of BADH from Suaeda corniculata (ScBADH) using reverse transcriptase-polymerase chain reaction and rapid amplification of cDNA ends. Next, we analyzed the expression profile of ScBADH using real-time PCR. The results showed that ScBADH expression was induced in the roots, stems, and leaves of S. corniculata seedlings under salt and drought stress. Next, ScBADH was overexpressed in Arabidopsis, resulting in the transgenic plants exhibiting enhanced tolerance over wild-type plants under salt and drought stress. We then analyzed the levels of glycine betaine and proline, as well as superoxide dismutase (SOD) activity, during salt stress in WT and transgenic Arabidopsis. The results indicated that overexpression of ScBADH produced more glycine betaine and proline, and increased SOD activity under NaCl treatment. Our results suggest that ScBADH might be a positive regulator in plants during the response to NaCl.
Assuntos
Betaína-Aldeído Desidrogenase/genética , Chenopodiaceae/genética , Proteínas de Plantas/genética , Betaína/metabolismo , Betaína-Aldeído Desidrogenase/metabolismo , Chenopodiaceae/enzimologia , Clonagem Molecular , Secas , Regulação da Expressão Gênica de Plantas , Glicina/metabolismo , Proteínas de Plantas/metabolismo , Prolina/metabolismo , Salinidade , Estresse Fisiológico , Superóxido Dismutase/metabolismoRESUMO
The lack of available transcriptome data for plants of no economic or agronomic importance limits the identification of miRNAs in many species. Considering the possible similarity of the transcriptome between related species, the present study used expressed sequence tags (ESTs) of Suaeda salsa and Suaeda glauca to identify conserved miRNAs, which were validated in a halophyte, Suaeda maritima, with the aim of identifying salt-responsive miRNAs from naturally salt-tolerant plants, information on which is limited. In this study, computational analysis predicted three miRNA sequences by mapping non-redundant miRNA sequences from miRBase 16.0 on 1534 ESTs of S. salsa and S. glauca. The expression of one could be validated in S. maritima, and was named sma-miR1867. This miRNA was downregulated in response to NaCl treatment. It was predicted to target ferredoxin-thioredoxin reductase (FTR), cell division control protein 6 (CDC6), and ubiquitin-protein ligase (UPL) in S. salsa and/or S. glauca. However, only UPL could be amplified in S. maritima, and RT-qPCR showed that it was upregulated in response to NaCl treatment. These results indicate that, in halophytes, FTR and CDC6 may promote carbon metabolism and cell division, respectively, in the presence of salt, while UPL may regulate the abundance of proteins that are important for salt tolerance in halophytes. Thus, sma-miR1867 could be an essential component of salt resistance in halophytes.
Assuntos
Chenopodiaceae/genética , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Proteínas de Plantas/genética , RNA de Plantas/genética , Transcriptoma , Sequência de Bases , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Chenopodiaceae/efeitos dos fármacos , Chenopodiaceae/metabolismo , Biologia Computacional , Proteínas Ferro-Enxofre/genética , Proteínas Ferro-Enxofre/metabolismo , MicroRNAs/metabolismo , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Oxirredutases/genética , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , RNA de Plantas/metabolismo , Tolerância ao Sal/genética , Plantas Tolerantes a Sal , Alinhamento de Sequência , Cloreto de Sódio/farmacologia , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Spatial and temporal regulation of phosphoenolpyruvate carboxylase (PEPC) is critical to the function of C(4) photosynthesis. The photosynthetic isoform of PEPC in the cytosol of mesophyll cells in Kranz-type C(4) photosynthesis has distinctive kinetic and regulatory properties. Some species in the Chenopodiaceae family perform C(4) photosynthesis without Kranz anatomy by spatial separation of initial fixation of atmospheric CO(2) via PEPC from C(4) acid decarboxylation and CO(2) donation to Rubisco within individual chlorenchyma cells. We studied molecular and functional features of PEPC in two single-cell functioning C(4) species (Bienertia sinuspersici, Suaeda aralocaspica) as compared to Kranz type (Haloxylon persicum, Salsola richteri, Suaeda eltonica) and C(3) (Suaeda linifolia) chenopods. It was found that PEPC from both types of C(4) chenopods displays higher specific activity than that of the C(3) species and shows kinetic and regulatory characteristics similar to those of C(4) species in other families in that they are subject to light/dark regulation by phosphorylation and display differential malate sensitivity. Also, the deduced amino acid sequence from leaf cDNA indicates that the single-cell functioning C(4) species possesses a Kranz-type C(4) isoform with a Ser in the amino terminal. A phylogeny of PEPC shows that isoforms in the two single-cell functioning C(4) species are in a clade with the C(3) and Kranz C(4) Suaeda spp. with high sequence homology. Overall, this study indicates that B. sinuspersici and S. aralocaspica have a C(4)-type PEPC similar to that in Kranz C(4) plants, which likely is required for effective function of C(4) photosynthesis.