In plants, the bZIP (basic leucine zipper) transcription factors regulate diverse functions, including processes such as plant development and stress response. However, few have been functionally characterized in maize (Zea mays). In this study, we cloned ZmbZIP72, a bZIP transcription factor gene from maize, which had only one copy in the maize genome and harbored three introns. Analysis of the amino acid sequence of ZmbZIP72 revealed a highly conserved bZIP DNA-binding domain in its C-terminal region, and four conserved sequences distributed in N- or C-terminal region. The ZmbZIP72 gene expressed differentially in various organs of maize plants and was induced by abscisic acid, high salinity, and drought treatment in seedlings. Subcellular localization analysis in onion epidermal cells indicated that ZmbZIP72 was a nuclear protein. Transactivation assay in yeast demonstrated that ZmbZIP72 functioned as a transcriptional activator and its N terminus (amino acids 23-63) was necessary for the transactivation activity. Heterologous overexpression of ZmbZIP72 improved drought and partial salt tolerance of transgenic Arabidopsis plants, as determined by physiological analyses of leaf water loss, electrolyte leakage, proline content, and survival rate under stress. In addition, the seeds of ZmbZIP72-overexpressing transgenic plants were hypersensitive to ABA and osmotic stress. Moreover, overexpression of ZmbZIP72 enhanced the expression of ABA-inducible genes such as RD29B, RAB18, and HIS1-3. These results suggest that the ZmbZIP72 protein functions as an ABA-dependent transcription factor in positive modulation of abiotic stress tolerance and may be a candidate gene with potential application in molecular breeding to enhance stress tolerance in crops.
"In contrast, the expression level of ZmWRKY92.1 has no obvious change in CR under salt stress, but is slightly down-regulated in PR and SR, indicating that ZmWRKY92.1 might act as a negative regulator of salt stress response. On the other hand, bZIP TFs function as ABA-dependent transcription factors and may be candidate genes enhancing crops stress tolerance [33, 55]. With the result of RNA-seq analysis, ZmbZIP23 expression was up-regulated by salt treatment in maize CR and PR, suggesting that ZmbZIP23 might play a partial role in response to salt stress. "
[Show abstract][Hide abstract] ABSTRACT: Background
Protein phosphatases (PPs) play critical roles in various cellular processes through the reversible protein phosphorylation that dictates many signal transduction pathways among organisms. Recently, PPs in Arabidopsis and rice have been identified, while the whole complement of PPs in maize is yet to be reported.
In this study, we have identified 159 PP-encoding genes in the maize genome. Phylogenetic analyses categorized the ZmPP gene family into 3 classes (PP2C, PTP, and PP2A) with considerable conservation among classes. Similar intron/exon structural patterns were observed in the same classes. Moreover, detailed gene structures and duplicative events were then researched. The expression profiles of ZmPPs under different developmental stages and abiotic stresses (including salt, drought, and cold) were analyzed using microarray and RNA-seq data. A total of 152 members were detected in 18 different tissues representing distinct stages of maize plant developments. Under salt stress, one gene was significantly up-expressed in seed root (SR) and one gene was down-expressed in primary root (PR) and crown root (CR), respectively. As for drought stress condition, 13 genes were found to be differentially expressed in leaf, out of which 10 were up-regulated and 3 exhibited down-regulation. Additionally, 13 up-regulated and 3 down-regulated genes were found in cold-tolerant line ETH-DH7. Furthermore, real-time PCR was used to confirm the expression patterns of ZmPPs.
Our results provide new insights into the phylogenetic relationships and characteristic functions of maize PPs and will be useful in studies aimed at revealing the global regulatory network in maize abiotic stress responses, thereby contributing to the maize molecular breeding with enhanced quality traits.
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The online version of this article (doi:10.1186/1471-2164-15-773) contains supplementary material, which is available to authorized users.
"The basic region leucine zipper (bZIP) family of TFs is exclusively present in eukaryotes and regulates diverse functions such as plant development and stress responses (Deppmann et al., 2004; Ying et al., 2012). This family of TFs is characterized by a 40–80 amino acid long conserved bZIP domain, hence its name (Correa et al., 2008; Nijhawan et al., 2008). "
[Show abstract][Hide abstract] ABSTRACT: Drought is one of the major constraints in crop production and has an effect on a global scale. In order to improve crop production, it is necessary to understand how plants respond to stress. A good understanding of regulatory mechanisms involved in plant responses during drought will enable researchers to explore and manipulate key regulatory points in order to enhance stress tolerance in crops. Transcription factors (TFs) have played an important role in crop improvement from the dawn of agriculture. TFs are, therefore, good candidates for genetic engineering to improve crop tolerance to drought because of their role as master regulators. TFs are major components in regulatory pathways and may control clusters of genes that make them ideal candidates to regulate traits that were controlled by multiple genes such as drought. Many families of TFs, such as CCAAT, homeodomain, bHLH, NAC, AP2/ERF, bZIP and WRKY have members that may have the potential to be tools for improving crop tolerance to drought. In this review, the roles of TFs as tools to improve drought tolerance in crops are discussed. The review also focuses on current strategies in the use of TFs with emphasis on several major TF families in improving drought tolerance of major crops. Finally, many promising transgenic lines that may have improved drought responses have been poorly characterized, and consequently their usefulness in the field is uncertain. New advances in high-throughput phenotyping, both greenhouse and field based, should facilitate improved phenomics of transgenic lines. Systems biology approaches should then define the underlying changes that result in higher yields under water stress conditions. These new technologies should help show whether manipulating TFs can have effects on yield under field conditions.
Omics A Journal of Integrative Biology 07/2014; 18(10). DOI:10.1089/omi.2013.0177 · 2.36 Impact Factor
"AtRAB18 is a well-known drought- and ABA-responsive gene used in several studies as a marker for drought and ABA treatments , , . RAB18 encodes a protein involved in membrane vesicle transport, and its function has been associated with the recycling of molecules, the removal of existing molecules from cellular compartments, and their replacement with newly synthesized molecules during stress adaptation . "
[Show abstract][Hide abstract] ABSTRACT: Rhythms produced by the endogenous circadian clock play a critical role in allowing plants to respond and adapt to the environment. While there is a well-established regulatory link between the circadian clock and responses to abiotic stress in model plants, little is known of the circadian system in crop species like soybean. This study examines how drought impacts diurnal oscillation of both drought responsive and circadian clock genes in soybean. Drought stress induced marked changes in gene expression of several circadian clock-like components, such as LCL1-, GmELF4- and PRR-like genes, which had reduced expression in stressed plants. The same conditions produced a phase advance of expression for the GmTOC1-like, GmLUX-like and GmPRR7-like genes. Similarly, the rhythmic expression pattern of the soybean drought-responsive genes DREB-, bZIP-, GOLS-, RAB18- and Remorin-like changed significantly after plant exposure to drought. In silico analysis of promoter regions of these genes revealed the presence of cis-elements associated both with stress and circadian clock regulation. Furthermore, some soybean genes with upstream ABRE elements were responsive to abscisic acid treatment. Our results indicate that some connection between the drought response and the circadian clock may exist in soybean since (i) drought stress affects gene expression of circadian clock components and (ii) several stress responsive genes display diurnal oscillation in soybeans.
PLoS ONE 01/2014; 9(1):e86402. DOI:10.1371/journal.pone.0086402 · 3.23 Impact Factor
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