Functional analyses of the maize CKS2 gene promoter in response to abiotic stresses and hormones

In our previous research, we showed that the cyclin-dependent kinase regulatory subunit (CKS2) in maize (Zea mays L.) was induced by water deficit and cold stress. To elucidate its expression patterns under adversity, we isolated and characterized its promoter (PZmCKS2). A series of PZmCKS2-deletion derivatives, P0–P3, from the translation start code (?1,455, ?999, ?367, and ?3 bp) was fused to the β-glucuronidase (GUS) reporter gene, and each deletion construct was analyzed by Agrobacterium-mediated steady transformation into Arabidopsis. Leaves were then subjected to dehydration, cold, abscisic acid (ABA), salicylic acid (SA), and methyl jasmonic acid (MeJA). Sequence analysis showed that several stress-related cis-acting elements (MBS, CE3, TGA element, and ABRE) were located within the promoter. Deletion analysis of the promoter, PZmCKS2, suggested that the ?999 bp promoter region was required for the highest basal expression of GUS, and the ?367 bp sequence was the minimal promoter for ZmCKS2 activation by low temperature, ABA, and MeJA. The cis-acting element ABRE was necessary for promoter activation by exogenous ABA.     

Isolation and functional analysis of cotton universal stress protein promoter in response to phytohormones and abiotic stresses

The 949 bp promoter fragment upstream from the translation initiation site of the GUSP gene encoding a universal stress protein was isolated from the genomic DNA of Gossypium arboreum. Some putative cis-acting elements involved in stress responses including E-box, ABRE, DPBF-box, and MYB-core elements were found in the promoter region. In an Agrobacterium-mediated transient expression assay, strong activation of the GUSP full promoter region occurred in tobacco leaves following dehydration, abscisic acid, salt, heavy metal, gibberellic acid and dark treatments. Deletion analysis of the promoter revealed that the dehydration, abscisic acid and salt responses were affected by the deletion between −208 and −949 bp and showed 2–4-fold induction. However, in response to dark, gibberellic acid and heavy metals the induction was only 2-fold. These findings further our understanding of the regulation of GUSP expression. This is an important study as no report of this universal stress protein promoter is available in literature.     

菜用大豆CIPK基因对逆境胁迫及激素的响应特征

CIPK(calcineurin B-like-interacting protein kinase)是一类丝氨酸/苏氨酸蛋白激酶,在植物响应逆境胁迫和激素信号转导中发挥重要作用。本研究利用大豆基因组数据库,在全基因组水平鉴定获得52个CIPK蛋白激酶。蛋白比对分析发现所有Gm CIPK含有高度保守特征性的N端激酶区、连接区和C端调控区。系统进化树分析发现大豆Gm CIPK与拟南芥、水稻CIPK分类一致,分为4个亚家族,且每个亚家族含有3个不同物种的成员,表明Gm CIPK基因的分化早于物种的分化。启动子分析表明,多数Gm CIPK基因的启动子区含有逆境和激素应答元件。组织表达分析发现,Gm CIPK基因呈现多样化的组织表达特性。进一步选取组织表达量相对较高的14个Gm CIPK进行荧光定量PCR分析,结果表明这些菜用大豆CIPK基因在不同程度上均受高温、干旱、高盐胁迫以及ABA、ACC、SA、Me JA激素的诱导表达。采用蛋白同源比对和蛋白互作在线数据库对拟南芥及大豆同源CIPK蛋白激酶与其他蛋白的互作关系进行了预测分析,发现17对同源CIPK与其他蛋白(激酶、磷酸酶、转录因子等)存在互作。本研究为菜用大豆CIPK基因的功能研究与利用奠定了基础。     

Regulation of the rose Rh-PIP2;1 promoter by hormones and abiotic stresses in Arabidopsis

Our previous work has indicated that an ethylene-responsive aquaporin gene, Rh-PIP2;1, played an important role in the epidermal cell expansion of rose petals. In this work, we isolated an 896 bp promoter sequence of the Rh-PIP2;1 and found that the promoter was rare in plants, occurring with an Inr motif, but without a TATA box. In transgenic Arabidopsis harboring the Rh-PIP2;1 promoter::GUS construct, the activity of Rh-PIP2;1 promoter was found to be developmental-dependent in almost all of the tested organs, and was particularly active in organs that were rapidly expanding, and in tissues with high water flux capacity. Moreover, the promoter activity was inhibited by ACC, ABA, NaCl, and cold in the roots of 3 or 6-day-old plants, and was increased by GA₃ and mannitol in the rosettes of 9 or 12-day-old plants. Deleting the fragment from −886 to −828 resulted in nearly complete disappearance of the promoter activity in roots, and a substantial decrease in the leaves, hypocotyls and floral organs. Taken together, our results indicated that the Rh-PIP2;1 promoter responded to hormones and abiotic stresses in a developmental- and spatial-dependent manner, and the −886 to −828 region was crucial for the activity of the Rh-PIP2;1 promoter. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Y. Li and Z. Wu contributed to this work equally.     

Brassinosteroids and their role in response of plants to abiotic stresses

Brassinosteroids (BRs) are polyhydroxylated steroidal plant hormones that play pivotal role in the regulation of various plant growth and development processes. BR biosynthetic or signaling mutants clearly indicate that these plant steroids are essential for regulating a variety of physiological processes including cellular expansion and proliferation, vascular differentiation, male fertility, timing senescence, and leaf development. Moreover, BRs regulate the expression of hundreds of genes, affect the activity of numerous metabolic pathways, and help to control overall developmental programs leading to morphogenesis. On the other hand, the potential application of BRs in agriculture to improve growth and yield under various stress conditions including drought, salinity, extreme temperatures, and heavy metal (Cd, Cu, Al, and Ni) toxicity, is of immense significance as these stresses severely hamper the normal metabolism of plants. Keeping in mind the multifaceted role of BRs, an attempt has been made to cover the various aspects mediated by BRs particularly under stress conditions and a possible mechanism of action of BRs has also been suggested.     

Cytokinin action in response to abiotic and biotic stresses in plants

The phytohormone cytokinin was originally discovered as a regulator of cell division. Later, it was described to be involved in regulating numerous processes in plant growth and development including meristem activity, tissue patterning, and organ size. More recently, diverse functions for cytokinin in the response to abiotic and biotic stresses have been reported. Cytokinin is required for the defence against high light stress and to protect plants from a novel type of abiotic stress caused by an altered photoperiod. Additionally, cytokinin has a role in the response to temperature, drought, osmotic, salt, and nutrient stress. Similarly, the full response to certain plant pathogens and herbivores requires a functional cytokinin signalling pathway. Conversely, different types of stress impact cytokinin homeostasis. The diverse functions of cytokinin in responses to stress and crosstalk with other hormones are described. Its emerging roles as a priming agent and as a regulator of growth‐defence trade‐offs are discussed.     

Molecular analyses of tomato GS,GOGAT and GDH gene families and their response to abiotic stresses

Glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) are closely related enzymes in plant nitrogen metabolism and potential targets for improving nitrogen use efficiency. However, little research has focused on the enzyme-encoding genes in tomato. Here, a comprehensive study of these genes was conducted. Six GS genes, two GOGAT genes and five GDH genes were identified in tomato. Bioinformatics and gene expression analyses suggested that these genes evolved species-specific regulatory properties and biological functions in tomato. SlNADH-GOGAT, SlGS1.1 and SlNAD-GDHB1 were abundantly expressed in roots, SlGS1.1 can be induced by nitrogen deprivation, and SlGS1.2, SlGS1.3, SlNADH-GOGAT and SlNAD-GDHB1 can be induced by the re-supply of nitrogen after 5 days of deprivation, they may play key roles in primary nitrogen assimilation. SlFd-GOGAT, SlGS1.1 and SlNAD-GDHA1-A2 were also highly expressed in fruits, indicating their important roles in fruit development and ripening. Tomato GS, GOGAT and GDH may be involved in stress responsiveness, since most of these genes modified their expression levels under drought, cold or heat stress treatment. We believe these findings will assist in the exploration of the genes’ biological functions and regulatory mechanisms, as well as the studies to improve nitrogen use efficiency, stress resistance and fruit quality in tomato.     

Cyclic nucleotide-gated ion channel gene family in rice,identification, characterization and experimental analysis of expression response to plant hormones,biotic and abiotic stresses

Background

Cyclic nucleotide-gated channels (CNGCs) are Ca²⁺-permeable cation transport channels, which are present in both animal and plant systems. They have been implicated in the uptake of both essential and toxic cations, Ca²⁺ signaling, pathogen defense, and thermotolerance in plants. To date there has not been a genome-wide overview of the CNGC gene family in any economically important crop, including rice (Oryza sativa L.). There is an urgent need for a thorough genome-wide analysis and experimental verification of this gene family in rice.

Results

In this study, a total of 16 full length rice CNGC genes distributed on chromosomes 1–6, 9 and 12, were identified by employing comprehensive bioinformatics analyses. Based on phylogeny, the family of OsCNGCs was classified into four major groups (I-IV) and two sub-groups (IV-A and IV- B). Likewise, the CNGCs from all plant lineages clustered into four groups (I-IV), where group II was conserved in all land plants. Gene duplication analysis revealed that both chromosomal segmentation (OsCNGC1 and 2, 10 and 11, 15 and 16) and tandem duplications (OsCNGC1 and 2) significantly contributed to the expansion of this gene family. Motif composition and protein sequence analysis revealed that the CNGC specific domain “cyclic nucleotide-binding domain (CNBD)” comprises a “phosphate binding cassette” (PBC) and a “hinge” region that is highly conserved among the OsCNGCs. In addition, OsCNGC proteins also contain various other functional motifs and post-translational modification sites. We successively built a stringent motif: (LI-X(2)-[GS]-X-[FV]-X-G-[1]-ELL-X-W-X(12,22)-SA-X(2)-T-X(7)-[EQ]-AF-X-L) that recognizes the rice CNGCs specifically. Prediction of cis-acting regulatory elements in 5′ upstream sequences and expression analyses through quantitative qPCR demonstrated that OsCNGC genes were highly responsive to multiple stimuli including hormonal (abscisic acid, indoleacetic acid, kinetin and ethylene), biotic (Pseudomonas fuscovaginae and Xanthomonas oryzae pv. oryzae) and abiotic (cold) stress.

Conclusions

There are 16 CNGC genes in rice, which were probably expanded through chromosomal segmentation and tandem duplications and comprise a PBC and a “hinge” region in the CNBD domain, featured by a stringent motif. The various cis-acting regulatory elements in the upstream sequences may be responsible for responding to multiple stimuli, including hormonal, biotic and abiotic stresses.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-853) contains supplementary material, which is available to authorized users.     

Molecular dissection of the response of a rice leucine-rich repeat receptor-like kinase (LRR-RLK) gene to abiotic stresses

Leucine-rich repeat (LRR) receptor-like kinase (RLK) proteins play key roles in a variety of biological pathways. In a previous study, we analyzed the members of the rice LRR-RLK gene family using in silico analysis. A total of 23 LRR-RLK genes were selected based on the expression patterns of a genome-wide dataset of microarrays. The Oryza sativa gamma-ray induced LRR-RLK1 (OsGIRL1) gene was highly induced by gamma irradiation. Therefore, we studied its expression pattern in response to various different abiotic and phytohormone treatments. OsGIRL1 was induced on exposure to abiotic stresses such as salt, osmotic, and heat, salicylic acid (SA), and abscisic acid (ABA), but exhibited downregulation in response to jasmonic acid (JA) treatment. The OsGIRL1 protein was clearly localized at the plasma membrane. The truncated proteins harboring juxtamembrane and kinase domains (or only harboring a kinase domain) exhibited strong autophosphorylation. The biological function of OsGIRL1 was investigated via heterologous overexpression of this gene in Arabidopsis plants subjected to gamma-ray irradiation, salt stress, osmotic stress, and heat stress. A hypersensitive response was observed in response to salt stress and heat stress, whereas a hyposensitive response was observed in response to gamma-ray treatment and osmotic stress. These results provide critical insights into the molecular functions of the rice LRR-RLK genes as receptors of external signals.