CaZF, a plant transcription factor functions through and parallel to HOG and calcineurin pathways in Saccharomyces cerevisiae to provide osmotolerance

Characterization of ZAT12 protein from Prunus persica: role in fruit chilling injury tolerance and identification of gene targets

MAIN CONCLUSION

PpZAT12, a transcription factor differentially expressed in peach varieties with distinct susceptibility tochilling injury (CI), is a potential candidate gene for CI tolerance by regulating several identified gene targets. ZAT (zinc finger of Arabidopsis thaliana) proteins play roles in multiple abiotic stress tolerance in Arabidopsis and other species; however, there are few reports on these transcription factors (TFs) in fruit crops. This study aimed to evaluate PpZAT12, a C2H2 TF up-regulated in peach fruit by a heat treatment applied before postharvest cold storage for reducing chilling injury (CI) symptoms. Here, the expression of PpZAT12 in different tissues and fruits subjected to either postharvest heat or cold treatments, was evaluated in peach varieties with differential susceptibility to develop CI. PpZAT12 increased by cold storage in CI-resistant cultivars ('Elegant Lady' and 'Rojo 2'), while it was not modified in a cultivar susceptible to develop CI ('Flordaking'). Besides, we expressed PpZAT12 in Arabidopsis (35S::PpZAT12) and found that these plants show impaired plant growth and development, rendering small plants with senescence delay and aborted seeds. We applied a proteomic approach to decipher the peptides responding to PpZAT12 in Arabidopsis and found 348 differential expressed proteins (DEPs) relative to the wild type. Besides, comparing the DEPs between Arabidopsis plants expressing PpZAT12 or AtZAT12 (35S::AtZAT12) we found common and specific responses to these TFs. Based on the proteomic information obtained here and published data about AtZAT12, we searched ZAT12-targets in peach allowing the identification of a putative ZAT12 regulon in this species. The identified peach ZAT12-protein targets could underlie the differential susceptibility to CI among different peach varieties and can be used as future targets to improve adaptation to refrigeration in fleshy fruits.

A 21-bp InDel in the promoter of STP1 selected during tomato improvement accounts for soluble solid content in fruits

Domestication and improvement are important processes that generate the variation in genome and phonotypes underlying crop improvement. Unfortunately, during selection for certain attributes, other valuable traits may be inadvertently discarded. One example is the decline in fruit soluble solids content (SSC) during tomato breeding. Several genetic loci for SSC have been identified, but few reports on the underlying mechanisms are available. In this study we performed a genome-wide association study (GWAS) for SSC of the red-ripe fruits in a population consisting of 481 tomato accessions with large natural variations and found a new quantitative trait locus, STP1, encoding a sugar transporter protein. The causal variation of STP1, a 21-bp InDel located in the promoter region 1124 bp upstream of the start codon, alters its expression. STP1 ^Insertion accessions with an 21-bp insertion have higher SSC than STP1 ^Deletion accessions with the 21-bp deletion. Knockout of STP1 in TS-23 with high SSC using CRISPR/Cas9 greatly decreased SSC in fruits. In vivo and in vitro assays demonstrated that ZAT10-LIKE, a zinc finger protein transcription factor (ZFP TF), can specifically bind to the promoter of STP1 ^Insertion to enhance STP1 expression, but not to the promoter of STP1 ^Deletion , leading to lower fruit SSC in modern tomatoes. Diversity analysis revealed that STP1 was selected during tomato improvement. Taking these results together, we identified a naturally occurring causal variation underlying SSC in tomato, and a new role for ZFP TFs in regulating sugar transporters. The findings enrich our understanding of tomato evolution and domestication, and provide a genetic basis for genome design for improving fruit taste.

Discovery of DNA polymorphisms via whole genome resequencing and their functional relevance in salinity stress response in chickpea

Salinity stress is one of the major constraints for plant growth and yield. The salinity stress response of different genotypes of crop plants may largely be governed by DNA polymorphisms. To determine the molecular genetic factors involved in salinity stress tolerance in chickpea, we performed a whole genome resequencing data analysis of three each of salinity-sensitive and salinity-tolerant genotypes. A total of 6173 single nucleotide polymorphisms and 920 insertions and deletions differentiating the chickpea genotypes with contrasting salinity stress responses were identified. Gene ontology analysis revealed the enrichment of functional terms related to stress response and development among the genes harboring DNA polymorphisms in their promoter and/or coding regions. DNA polymorphisms located within the cis-regulatory motifs of the quantitative trait loci (QTL)-associated and abiotic stress related genes were identified, which may influence salinity stress response via modulating binding affinity of the transcription factors. Several genes including QTL-associated and abiotic stress response related genes harboring DNA polymorphisms exhibited differential expression in response to salinity stress especially at the reproductive stage of development in the salinity-tolerant genotype. Furthermore, effects of non-synonymous DNA polymorphisms on mutational sensitivity and structural integrity of the encoded proteins by the candidate QTL-associated and abiotic stress response related genes were revealed. The results suggest that DNA polymorphisms may determine salinity stress response via influencing differential gene expression in genotype and/or stage-dependent manner. Altogether, we provide a high-quality set of DNA polymorphisms and candidate genes that may govern salinity stress tolerance in chickpea.

Altered Expression of an FT Cluster Underlies a Major Locus Controlling Domestication-Related Changes to Chickpea Phenology and Growth Habit

Flowering time is a key trait in breeding and crop evolution, due to its importance for adaptation to different environments and for yield. In the particular case of chickpea, selection for early phenology was essential for the successful transition of this species from a winter to a summer crop. Here, we used genetic and expression analyses in two different inbred populations to examine the genetic control of domestication-related differences in flowering time and growth habit between domesticated chickpea and its wild progenitor Cicer reticulatum. A single major quantitative trait locus for flowering time under short-day conditions [Days To Flower (DTF)3A] was mapped to a 59-gene interval on chromosome three containing a cluster of three FT genes, which collectively showed upregulated expression in domesticated relative to wild parent lines. An equally strong association with growth habit suggests a pleiotropic effect of the region on both traits. These results indicate the likely molecular explanation for the characteristic early flowering of domesticated chickpea, and the previously described growth habit locus Hg. More generally, they point to de-repression of this specific gene cluster as a conserved mechanism for achieving adaptive early phenology in temperate legumes.

OsbZIP48, a HY5 Transcription Factor Ortholog, Exerts Pleiotropic Effects in Light-Regulated Development

Plants have evolved an intricate network of sensory photoreceptors and signaling components to regulate their development. Among the light signaling components identified to date, HY5, a basic leucine zipper (bZIP) transcription factor, has been investigated extensively. However, most of the work on HY5 has been carried out in Arabidopsis (Arabidopsis thaliana), a dicot. In this study, based on homology search and phylogenetic analysis, we identified three homologs of AtHY5 in monocots; however, AtHYH (HY5 homolog) homologs are absent in the monocots analyzed. Out of the three homologs identified in rice (Oryza sativa), we have functionally characterized OsbZIP48OsbZIP48 was able to complement the Athy5 mutant. OsbZIP48 protein levels are developmentally regulated in rice. Moreover, the OsbZIP48 protein does not degrade in dark-grown rice and Athy5 seedlings complemented with OsbZIP48, which is in striking contrast to AtHY5. In comparison with AtHY5, which does not cause any change in hypocotyl length when overexpressed in Arabidopsis, the overexpression of full-length OsbZIP48 in rice transgenics reduced the plant height considerably. Microarray analysis revealed that OsKO2, which encodes ent-kaurene oxidase 2 of the gibberellin biosynthesis pathway, is down-regulated in OsbZIP48^OE and up-regulated in OsbZIP48^KD transgenics as compared with the wild type. Electrophoretic mobility shift assay showed that OsbZIP48 binds directly to the OsKO2 promoter. The RNA interference lines and the T-DNA insertional mutant of OsbZIP48 showed seedling-lethal phenotypes despite the fact that roots were more proliferative during early stages of development in the T-DNA insertional mutant. These data provide credible evidence that OsbZIP48 performs more diverse functions in a monocot system like rice in comparison with its Arabidopsis ortholog, HY5.

Improving Salt Tolerance of Chickpea Using Modern Genomics Tools and Molecular Breeding

INTRODUCTION

The high protein value, essential minerals, dietary fibre and notable ability to fix atmospheric nitrogen make chickpea a highly remunerative crop, particularly in low-input food production systems. Of the variety of constraints challenging chickpea productivity worldwide, salinity remains of prime concern owing to the intrinsic sensitivity of the crop. In view of the projected expansion of chickpea into arable and salt-stressed land by 2050, increasing attention is being placed on improving the salt tolerance of this crop. Considerable effort is currently underway to address salinity stress and substantial breeding progress is being made despite the seemingly highly-complex and environment-dependent nature of the tolerance trait.

CONCLUSION

This review aims to provide a holistic view of recent advances in breeding chickpea for salt tolerance. Initially, we focus on the identification of novel genetic resources for salt tolerance via extensive germplasm screening. We then expand on the use of genome-wide and cost-effective techniques to gain new insights into the genetic control of salt tolerance, including the responsive genes/QTL(s), gene(s) networks/cross talk and intricate signalling cascades.

NbCZF1, a Novel C2H2-Type Zinc Finger Protein, as a New Regulator of SsCut-Induced Plant Immunity in Nicotiana benthamiana

SsCut, which functions as an elicitor, can induce plant immunity. In this study, we utilized Nicotiana benthamiana and virus-induced gene silencing to decrease the expression of > 2,500 genes individually. Using this forward genetics approach, several genes were identified that, when silenced, compromised SsCut-triggered cell death based on a cell death assay. A C2H2-type zinc finger gene was isolated from N. benthamiana Sequence analysis indicated that the gene encodes a 27 kDa protein with 253 amino acids containing two typical C2H2-type zinc finger domains; this gene was named NbCZF1 We found that SsCut-induced cell death could be inhibited by virus-induced gene silencing of NbCZF1 in N. benthamiana In addition, SsCut induces stomatal closure, accompanied by reactive oxygen species (ROS) production by NADPH oxidases and nitric oxide (NO) production. NbCZF1-silenced plants showed impaired SsCut-induced stomatal closure, decreased SsCut-induced production of ROS and NO in guard cells and reduced SsCut-induced resistance against Phytophthora nicotianae Taken together, these results demonstrate that the NbCZF1-ROS-NO pathway mediates multiple SsCut-triggered responses, including stomatal closure, hypersensitive responses and defense-related gene expression. This is the first report describing the function of a C2H2-type zinc finger protein in N. benthamiana.

Reconstruction of the High-Osmolarity Glycerol (HOG) Signaling Pathway from the Halophilic Fungus Wallemia ichthyophaga in Saccharomyces cerevisiae

The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like other fungi, W. ichthyophaga detects changes in environmental salinity mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with protein modeling data, our study reveals conserved and non-conserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.

A pathogenesis related-10 protein CaARP functions as aldo/keto reductase to scavenge cytotoxic aldehydes

Pathogenesis related-10 (PR-10) proteins are present as multigene family in most of the higher plants. The role of PR-10 proteins in plant is poorly understood. A sequence analysis revealed that a large number of PR-10 proteins possess conserved motifs found in aldo/keto reductases (AKRs) of yeast and fungi. We took three PR-10 proteins, CaARP from chickpea, ABR17 from pea and the major pollen allergen Bet v1 from silver birch as examples and showed that these purified recombinant proteins possessed AKR activity using various cytotoxic aldehydes including methylglyoxal and malondialdehyde as substrates and the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) as co-factor. Essential amino acids for this catalytic activity were identified by substitution with other amino acids. CaARP was able to discriminate between the reduced and oxidized forms of NADP independently of its catalytic activity and underwent structural change upon binding with NADPH. CaARP protein was preferentially localized in cytosol. When expressed in bacteria, yeast or plant, catalytically active variants of CaARP conferred tolerance to salinity, oxidative stress or cytotoxic aldehydes. CaARP-expressing plants showed lower lipid peroxidation product content in presence or absence of stress suggesting that the protein functions as a scavenger of cytotoxic aldehydes produced by metabolism and lipid peroxidation. Our result proposes a new biochemical property of a PR-10 protein.

A novel rice C2H2-type zinc finger protein, ZFP36, is a key player involved in abscisic acid-induced antioxidant defence and oxidative stress tolerance in rice

C2H2-type zinc finger proteins (ZFPs) have been shown to play important roles in the responses of plants to oxidative and abiotic stresses, and different members of this family might have different roles during stresses. Here a novel abscisic acid (ABA)- and hydrogen peroxide (H₂O₂)-responsive C2H2-type ZFP gene, ZFP36, is identified in rice. The analyses of ZFP36-overexpressing and silenced transgenic rice plants showed that ZFP36 is involved in ABA-induced up-regulation of the expression and the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Overexpression of ZFP36 in rice plants was found to elevate the activities of antioxidant enzymes and to enhance the tolerance of rice plants to water stress and oxidative stress. In contrast, an RNA interference (RNAi) mutant of ZFP36 had lower activities of antioxidant enzymes and was more sensitive to water stress and oxidative stress. ABA-induced H₂O₂ production and ABA-activated mitogen-activated protein kinases (MAPKs) were shown to regulate the expression of ZFP36 in ABA signalling. On the other hand, ZFP36 also regulated the expression of NADPH oxidase genes, the production of H₂O₂, and the expression of OsMPK genes in ABA signalling. These results indicate that ZFP36 is required for ABA-induced antioxidant defence, for the tolerance of rice plants to water stress and oxidative stress, and for the regulation of the cross-talk between NADPH oxidase, H₂O₂, and MAPK in ABA signalling.

A soybean C2H2-type zinc finger gene GmZF1 enhanced cold tolerance in transgenic Arabidopsis

Zinc finger proteins were involved in response to different environmental stresses in plant species. A typical Cys2/His2-type (C2H2-type) zinc finger gene GmZF1 from soybean was isolated and was composed of 172 amino acids containing two conserved C2H2-type zinc finger domains. Phylogenetic analysis showed that GmZF1 was clustered on the same branch with six C2H2-type ZFPs from dicotyledonous plants excepting for GsZFP1, and distinguished those from monocotyledon species. The GmZF1 protein was localized at the nucleus, and has specific binding activity with EP1S core sequence, and nucleotide mutation in the core sequence of EPSPS promoter changed the binding ability between GmZF1 protein and core DNA element, implying that two amino acid residues, G and C boxed in core sequence TGACAGTGTCA possibly play positive regulation role in recognizing DNA-binding sites in GmZF1 proteins. High accumulation of GmZF1 mRNA induced by exogenous ABA suggested that GmZF1 was involved in an ABA-dependent signal transduction pathway. Over-expression of GmZF1 significantly improved the contents of proline and soluble sugar and decreased the MDA contents in the transgenic lines exposed to cold stress, indicating that transgenic Arabidopsis carrying GmZF1 gene have adaptive mechanisms to cold stress. Over-expression of GmZF1 also increased the expression of cold-regulated cor6.6 gene by probably recognizing protein-DNA binding sites, suggesting that GmZF1 from soybean could enhance the tolerance of Arabidopsis to cold stress by regulating expression of cold-regulation gene in the transgenic Arabidopsis.

Promoter of CaZF, a chickpea gene that positively regulates growth and stress tolerance, is activated by an AP2-family transcription factor CAP2

Plants respond to different forms of stresses by inducing transcription of a common and distinct set of genes by concerted actions of a cascade of transcription regulators. We previously reported that a gene, CaZF encoding a C2H2-zinc finger family protein from chickpea (Cicer arietinum) imparted high salinity tolerance when expressed in tobacco plants. We report here that in addition to promoting tolerance against dehydration, salinity and high temperature, the CaZF overexpressing plants exhibited similar phenotype of growth and development like the plants overexpressing CAP2, encoding an AP2-family transcription factor from chickpea. To investigate any relationship between these two genes, we performed gene expression analysis in the overexpressing plants, promoter-reporter analysis and chromatin immunoprecipitation. A number of transcripts that exhibited enhanced accumulation upon expression of CAP2 or CaZF in tobacco plants were found common. Transient expression of CAP2 in chickpea leaves resulted in increased accumulation of CaZF transcript. Gel mobility shift and transient promoter-reporter assays suggested that CAP2 activates CaZF promoter by interacting with C-repeat elements (CRTs) in CaZF promoter. Chromatin immunoprecipitation (ChIP) assay demonstrated an in vivo interaction of CAP2 protein with CaZF promoter.

Catharanthus roseus mitogen-activated protein kinase 3 confers UV and heat tolerance to Saccharomyces cerevisiae

Catharanthus roseus is an important source of pharmaceutically important Monoterpenoid Indole Alkaloids (MIAs). Accumulation of many of the MIAs is induced in response to abiotic stresses such as wound, ultra violet (UV) irradiations, etc. Recently, we have demonstrated a possible role of CrMPK3, a C. roseus mitogen-activated protein kinase in stress-induced accumulation of a few MIAs. Here, we extend our findings using Saccharomyces cerevisiae to investigate the role of CrMPK3 in giving tolerance to abiotic stresses. Yeast cells transformed with CrMPK3 was found to show enhanced tolerance to UV and heat stress. Comparison of CrMPK3 and SLT2, a MAPK from yeast shows high-sequence identity particularly at conserved domains. Additionally, heat stress is also shown to activate a 43 kDa MAP kinase, possibly CrMPK3 in C. roseus leaves. These findings indicate the role of CrMPK3 in stress-induced MIA accumulation as well as in stress tolerance.

The salt-responsive transcriptome of Populus simonii × Populus nigra via DGE

In this study, the dynamic transcriptome of poplar (Populus simonii × Populus nigra) was investigated under salt stress using Solexa/illumine digital gene expression (DGE) technique. A total of 5453, 2372, and 1770 genes were shown to be differentially expressed after exposure to NaCl for 3 days, 6 days and 9 days, respectively. Differential expression patterns throughout salt stress were identified for 572 genes. Gene ontology classification analysis of these differentially expressed genes revealed that numerous genes mapped to "transporter activity" and "response to stress". The dynamic transcriptome expression profiles of poplar under salt stress obtained in this study may provide useful insights for further analysis of the mechanism of high salinity tolerance in plants. Furthermore, these differentially expressed genes under salt stress may allow identification of potential genes as suitable targets for biotechnological manipulation with the aim of improving poplar salt tolerance.

The heterologous expression in Arabidopsis of a chrysanthemum Cys2/His2 zinc finger protein gene confers salinity and drought tolerance

Zinc finger proteins (ZFPs) play an important role in plant growth and development. Here, we describe the isolation of CgZFP1, a Cys2/His2 (C(2)H(2)) ZFP gene, using RACE PCR from chrysanthemum, and the investigation of its function with ectopic expression in Arabidopsis. CgZFP1 contains two conserved C(2)H(2) regions, a nuclear localization domain (B box), a Leu-rich domain (L box) and a conserved DLN sequence (DLN box) close to its C-terminus. Its expression in the chrysanthemum leaf was strongly induced by salinity or drought, but not by ABA. Subcellular localization assay indicated that CgZFP1 protein is localized in nucleus in vivo. Yeast-one hybrid assay showed that CgZFP1 possesses transcriptional activation ability, heterologous expression of CgZFP1 conferred tolerance of transgenic Arabidopsis plants to both salinity and drought stresses. Under salinity stress, genes involved in osmotic adjustment, ROS scavenging, and ion homeostasis: Atlea3, AtP5CS2, AtProT1, and AtMnSOD, AtPOD, AtAPX1, and AtSOS1, AtSOS2, AtSOS3, AtNHX1 were enhanced in CgZFP1 transgenic Arabidopsis plants. Moreover, genes involved in the osmotic adjustment and oxidative stress responses: Atlea3, AtP5CS2, AtProT1, the aquaporin AtPIP2A, and AtMnSOD, AtPOD, AtAPX1 were induced in CgZFP1 transgenic Arabidopsis under drought stress. These results indicate CgZFP1 is an important regulator involved in the salt and drought stress response in plants.

Rice ASR1 protein with reactive oxygen species scavenging and chaperone-like activities enhances acquired tolerance to abiotic stresses in Saccharomyces cerevisiae

Abscisic acid stress ripening (ASR1) protein is a small hydrophilic, low molecular weight, and stress-specific plant protein. The gene coding region of ASR1 protein, which is induced under high salinity in rice (Oryza sativa Ilmi), was cloned into a yeast expression vector pVTU260 and transformed into yeast cells. Heterologous expression of ASR1 protein in transgenic yeast cells improved tolerance to abiotic stresses including hydrogen peroxide (H(2)O(2)), high salinity (NaCl), heat shock, menadione, copper sulfate, sulfuric acid, lactic acid, salicylic acid, and also high concentration of ethanol. In particular, the expression of metabolic enzymes (Fba1p, Pgk1p, Eno2p, Tpi1p, and Adh1p), antioxidant enzyme (Ahp1p), molecular chaperone (Ssb1p), and pyrimidine biosynthesis-related enzyme (Ura1p) was up-regulated in the transgenic yeast cells under oxidative stress when compared with wild-type cells. All of these enzymes contribute to an alleviated redox state to H2O2-induced oxidative stress. In the in vitro assay, the purified ASR1 protein was able to scavenge ROS by converting H(2)O(2) to H(2)O. Taken together, these results suggest that the ASR1 protein could function as an effective ROS scavenger and its expression could enhance acquired tolerance of ROS-induced oxidative stress through induction of various cell rescue proteins in yeast cells.

ZFP5 encodes a functionally equivalent GIS protein to control trichome initiation

The Arabidopsis thaliana trichome development is a model system for understanding various aspects of plant cell development and differentiation. The C2H2 zinc finger proteins GIS, GIS2, and ZFP8 play important roles in controlling trichome initiation. In our recent study, we reported that a new C2H2 zinc finger protein, ZINC FINGER PROTEIN 5 (ZFP5), controls trichome cell development through GA signaling. ZFP5 acts upstream of GIS gene family and key trichome initiation regulators, and ZFP8 is the direct target gene of ZFP5. Here we show that ZFP5 encodes a protein functionally equivalent to GIS and GIS2 in controlling trichome initiation. Furthermore, similar to GIS2, ZFP5 is not involved in trichome branching.

Differential gene expression in roots of nematode-resistant and -susceptible peanut (Arachis hypogaea) cultivars in response to early stages of peanut root-knot nematode (Meloidogyne arenaria) parasitization

The peanut root-knot nematode (RKN, Meloidogyne arenaria) can cause significant yield losses in cultivated peanut (Arachis hypogaea). However, molecular events underlying successful RKN infection and host responses in peanut are sparsely understood. Using suppression subtractive hybridization (SSH), cDNA libraries, enriched with differentially expressed ESTs, were constructed from RKN-challenged root tissues in the pre-penetration and early infection stages from near-isogenic nematode-resistant and -susceptible peanut cultivars NemaTAM and Florunner. Following an initial screen of 960 expressed sequence tags (ESTs) for at least three-fold differential expression between the two libraries, 70 ESTs (36 from the NemaTAM-specific library and 34 from the Florunner-specific library) were identified and annotated into seven functional categories (stress responses, metabolism, transcriptional regulation, protein synthesis and/or modification, transport functions, cellular architecture and proteins with unknown functions). Discreet gene tag clusters primarily including pathogenesis related (PR), patatin-like proteins and universal stress related proteins (USPs), as well as those implicated in alleviation of oxidative stress were primarily represented in RKN-infected NemaTAM roots, reflective of a basal level of resistance operative against invading nematodes. However, significant transcriptional reprogramming and upregulation of genes implicated in modification of cellular architecture, adhesion, and proliferation marked an early onset of compatible host-pathogen interactions discernible in Florunner roots.

Functional analysis of a novel Cys2/His2-type zinc finger protein involved in salt tolerance in rice

The Cys2/His2-type zinc finger proteins have been implicated in different cellular processes involved in plant development and stress responses. Through microarray analysis, a salt-responsive zinc finger protein gene ZFP179 was identified and subsequently cloned from rice seedlings. ZFP179 encodes a 17.95 kDa protein with two C2H2-type zinc finger motifs having transcriptional activation activity. The real-time RT-PCR analysis showed that ZFP179 was highly expressed in immature spikes, and markedly induced in the seedlings by NaCl, PEG 6000, and ABA treatments. Overexpression of ZFP179 in rice increased salt tolerance and the transgenic seedlings showed hypersensitivity to exogenous ABA. The increased levels of free proline and soluble sugars were observed in transgenic plants compared to wild-type plants under salt stress. The ZFP179 transgenic rice exhibited significantly increased tolerance to oxidative stress, the reactive oxygen species (ROS)-scavenging ability, and expression levels of a number of stress-related genes, including OsDREB2A, OsP5CS OsProT, and OsLea3 under salt stress. Our studies suggest that ZFP179 plays a crucial role in the plant response to salt stress, and is useful in developing transgenic crops with enhanced tolerance to salt stress.

Functional analysis of a novel Cys2/His2-type zinc finger protein involved in salt tolerance in rice

The Cys2/His2-type zinc finger proteins have been implicated in different cellular processes involved in plant development and stress responses. Through microarray analysis, a salt-responsive zinc finger protein gene ZFP179 was identified and subsequently cloned from rice seedlings. ZFP179 encodes a 17.95 kDa protein with two C2H2-type zinc finger motifs having transcriptional activation activity. The real-time RT-PCR analysis showed that ZFP179 was highly expressed in immature spikes, and markedly induced in the seedlings by NaCl, PEG 6000, and ABA treatments. Overexpression of ZFP179 in rice increased salt tolerance and the transgenic seedlings showed hypersensitivity to exogenous ABA. The increased levels of free proline and soluble sugars were observed in transgenic plants compared to wild-type plants under salt stress. The ZFP179 transgenic rice exhibited significantly increased tolerance to oxidative stress, the reactive oxygen species (ROS)-scavenging ability, and expression levels of a number of stress-related genes, including OsDREB2A, OsP5CS OsProT, and OsLea3 under salt stress. Our studies suggest that ZFP179 plays a crucial role in the plant response to salt stress, and is useful in developing transgenic crops with enhanced tolerance to salt stress.

Analysis of gene expression in response to water deficit of chickpea (Cicer arietinum L.) varieties differing in drought tolerance

BACKGROUND

Chickpea (C. arietinum L.) ranks third in food legume crop production in the world. However, drought poses a serious threat to chickpea production, and development of drought-resistant varieties is a necessity. Unfortunately, cultivated chickpea has a high morphological but narrow genetic diversity, and understanding the genetic processes of this plant is hindered by the fact that the chickpea genome has not yet been sequenced and its EST resources are limited. In this study, two chickpea varieties having contrasting levels of drought-tolerance were analyzed for differences in transcript profiling during drought stress treatment by withdrawal of irrigation at different time points. Transcript profiles of ESTs derived from subtractive cDNA libraries constructed with RNA from whole seedlings of both varieties were analyzed at different stages of stress treatment.

RESULTS

A series of comparisons of transcript abundance between two varieties at different time points were made. 319 unique ESTs available from different libraries were categorized into eleven clusters according to their comparative expression profiles. Expression analysis revealed that 70% of the ESTs were more than two fold abundant in the tolerant cultivar at any point of the stress treatment of which expression of 33% ESTs were more than two fold high even under the control condition. 53 ESTs that displayed very high fold relative expression in the tolerant variety were screened for further analysis. These ESTs were clustered in four groups according to their expression patterns.

CONCLUSIONS

Annotation of the highly expressed ESTs in the tolerant cultivar predicted that most of them encoded proteins involved in cellular organization, protein metabolism, signal transduction, and transcription. Results from this study may help in targeting useful genes for improving drought tolerance in chickpea.

Increased tolerance of rice to cold, drought and oxidative stresses mediated by the overexpression of a gene that encodes the zinc finger protein ZFP245

ZFP245 is a cold- and drought-responsive gene that encodes a zinc finger protein in rice. The ZFP245 protein localizes in the nucleus and exhibits trans-activation activity. Transgenic rice plants overexpressing ZFP245 were generated and found to display high tolerance to cold and drought stresses. The transgenic plants did not exhibit growth retardation, but showed growth sensitivity against exogenous abscisic acid, increased free proline levels and elevated expression of rice pyrroline-5-carboxylatesynthetase and proline transporter genes under stress conditions. Overproduction of ZFP245 enhanced the activities of reactive oxygen species-scavenging enzymes under stress conditions and increased the tolerance of rice seedlings to oxidative stress. Our data suggest that ZFP245 may contribute to the tolerance of rice plants to cold and drought stresses by regulating proline levels and reactive oxygen species-scavenging activities, and therefore may be useful for developing transgenic crops with enhanced tolerance to abiotic stress.