The Arabidopsis Mutant stg1 Identifies a Function for TBP-Associated Factor 10 in Plant Osmotic Stress Adaptation

Identification of Salt-Sensitive and Salt-Tolerant Genes through Weighted Gene Co-Expression Networks across Multiple Datasets: A Centralization and Differential Correlation Analysis

Salt stress is a significant challenge that severely hampers rice growth, resulting in decreased yield and productivity. Over the years, researchers have identified biomarkers associated with salt stress to enhance rice tolerance. However, the understanding of the mechanism underlying salt tolerance in rice remains incomplete due to the involvement of multiple genes. Given the vast amount of genomics and transcriptomics data available today, it is crucial to integrate diverse datasets to identify key genes that play essential roles during salt stress in rice. In this study, we propose an integration of multiple datasets to identify potential key transcription factors. This involves utilizing network analysis based on weighted co-expression networks, focusing on gene-centric measurement and differential co-expression relationships among genes. Consequently, our analysis reveals 86 genes located in markers from previous meta-QTL analysis. Moreover, six transcription factors, namely LOC_Os03g45410 (OsTBP2), LOC_Os07g42400 (OsGATA23), LOC_Os01g13030 (OsIAA3), LOC_Os05g34050 (OsbZIP39), LOC_Os09g29930 (OsBIM1), and LOC_Os10g10990 (transcription initiation factor IIF), exhibited significantly altered co-expression relationships between salt-sensitive and salt-tolerant rice networks. These identified genes hold potential as crucial references for further investigation into the functions of salt stress response in rice plants and could be utilized in the development of salt-resistant rice cultivars. Overall, our findings shed light on the complex genetic regulation underlying salt tolerance in rice and contribute to the broader understanding of rice's response to salt stress.

Identification and validation of seed dormancy loci and candidate genes and construction of regulatory networks by WGCNA in maize introgression lines

KEY MESSAGE

Seventeen PHS-QTLs and candidate genes were obtained, including eleven major loci, three under multiple environments and two with co-localization by the other mapping methods; The functions of three candidate genes were validated using mutants; nine target proteins and five networks were filtered by joint analysis of GWAS and WGCNA. Seed dormancy (SD) and pre-harvest sprouting (PHS) affect yield, as well as grain and hybrid quality in seed production. Therefore, identification of genetic and regulatory pathways underlying PHS and SD is key to gene function analysis, allelic variation mining and genetic improvement. In this study, 78,360 SNPs by SLAF-seq of 230 maize chromosome segment introgression lines (ILs), PHS under five environments were used to conduct GWAS (genome wide association study) (a threshold of 1/n), and seventeen unreported PHS QTLs were obtained, including eleven QTLs with PVE > 10% and three QTLs under multiple environments. Two QTL loci were co-located between the other two genetic mapping methods. Using differential gene expression analyses at two stages of grain development, gene functional analysis of Arabidopsis mutants, and gene functional analysis in the QTL region, seventeen PHS QTL-linked candidate genes were identified, and their five molecular regulatory networks constructed. Based on the Arabidopsis T-DNA mutations, three candidate genes were shown to regulate for SD and PHS. Meanwhile, using RNA-seq of grain development, the weighted correlation network analysis (WGCNA) was performed, deducing five regulatory pathways and target genes that regulate PHS and SD. Based on the conjoint analysis of GWAS and WGCNA, four pathways, nine target proteins and target genes were revealed, most of which regulate cell wall metabolism, cell proliferation and seed dehydration tolerance. This has important theoretical and practical significance for elucidating the genetic basis of maize PHS and SD, as well as mining of genetic resources and genetic improvement of traits.

Exogenous melatonin improves salt tolerance mainly by regulating the antioxidant system in cyanobacterium Nostoc flagelliforme

Melatonin is a multifunctional nontoxic bio-stimulant or signaling molecule, generally distributing in different animal and plant organs for invigorating numerous physiological processes against abiotic stresses. In this study, we investigated the potential impact of melatonin on the cyanobacterium Nostoc flagelliforme when exposed to salt stress according to some biochemical and physiological parameters, such as relative electrolyte leakage, PSII activity, and photosynthetic pigments including chlorophyll a, phycocyanobilin, and phycoerythrobilin. We found that melatonin could also maintain K⁺ homeostasis in salt-stressed N. flagelliforme. These above results confirmed melatonin had multiple functions in hyperosmotic stress and ion stress caused by salinity. Notably, we observed melatonin could regulate the reactive oxygen species (ROS) signal and distinctly decrease the content of hydrogen peroxide and superoxide anion in salt-stressed cells, which were largely attributed to the increased antioxidant enzymes activities including catalase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase. Finally, qRT-PCR analysis showed that melatonin stimulated the expression of antioxidant genes (NfCAT, NfSOD, and NfGR). In general, our findings demonstrate melatonin has beneficial effects on N. flagelliforme under salt stress by intensively regulating antioxidant system.

Recent progress in understanding salinity tolerance in plants: Story of Na+/K+ balance and beyond

High salt concentrations in the growing medium can severely affect the growth and development of plants. It is imperative to understand the different components of salt-tolerant network in plants in order to produce the salt-tolerant cultivars. High-affinity potassium transporter- and myelocytomatosis proteins have been shown to play a critical role for salinity tolerance through exclusion of sodium (Na⁺) ions from sensitive shoot tissues in plants. Numerous genes, that limit the uptake of salts from soil and their transport throughout the plant body, adjust the ionic and osmotic balance of cells in roots and shoots. In the present review, we have tried to provide a comprehensive report of major research advances on different mechanisms regulating plant tolerance to salinity stress at proteomics, metabolomics, genomics and transcriptomics levels. Along with the role of ionic homeostasis, a major focus was given on other salinity tolerance mechanisms in plants including osmoregulation and osmo-protection, cell wall remodeling and integrity, and plant antioxidative defense. Major proteins and genes expressed under salt-stressed conditions and their role in enhancing salinity tolerance in plants are discussed as well. Moreover, this manuscript identifies and highlights the key questions on plant salinity tolerance that remain to be discussed in the future.

The Histone Acetyltransferase GCN5 and the Associated Coactivators ADA2: From Evolution of the SAGA Complex to the Biological Roles in Plants

Transcription of protein-encoding genes starts with forming a pre-initiation complex comprised of RNA polymerase II and several general transcription factors. To activate gene expression, transcription factors must overcome repressive chromatin structure, which is accomplished with multiprotein complexes. One such complex, SAGA, modifies the nucleosomal histones through acetylation and other histone modifications. A prototypical histone acetyltransferase (HAT) known as general control non-repressed protein 5 (GCN5), was defined biochemically as the first transcription-linked HAT with specificity for histone H3 lysine 14. In this review, we analyze the components of the putative plant SAGA complex during plant evolution, and current knowledge on the biological role of the key components of the HAT module, GCN5 and ADA2b in plants, will be summarized.

Knockdown of a Novel Gene OsTBP2.2 Increases Sensitivity to Drought Stress in Rice

Drought stress is a major environmental stress, which adversely affects the biological and molecular processes of plants, thereby impairing their growth and development. In the present study, we found that the expression level of OsTBP2.2 which encodes for a nucleus-localized protein member belonging to transcription factor IID (TFIID) family, was significantly induced by polyethylene glycol (PEG) treatment. Therefore, knockdown mutants of OsTBP2.2 gene were generated to investigate the role of OsTBP2.2 in rice response to drought stress. Under the condition of drought stress, the photosynthetic rate, transpiration rate, water use efficiency, and stomatal conductance were significantly reduced in ostbp2.2 lines compared with wild type, Dongjin (WT-DJ). Furthermore, the RNA-seq results showed that several main pathways involved in "MAPK (mitogen-activated protein kinase) signaling pathway", "phenylpropanoid biosynthesis", "defense response" and "ADP (adenosine diphosphate) binding" were altered significantly in ostbp2.2. We also found that OsPIP2;6, OsPAO and OsRCCR1 genes were down-regulated in ostbp2.2 compared with WT-DJ, which may be one of the reasons that inhibit photosynthesis. Our findings suggest that OsTBP2.2 may play a key role in rice growth and the regulation of photosynthesis under drought stress and it may possess high potential usefulness in molecular breeding of drought-tolerant rice.

Effects of green seaweed extract on Arabidopsis early development suggest roles for hormone signalling in plant responses to algal fertilisers

The growing population requires sustainable, environmentally-friendly crops. The plant growth-enhancing properties of algal extracts have suggested their use as biofertilisers. The mechanism(s) by which algal extracts affect plant growth are unknown. We examined the effects of extracts from the common green seaweed Ulva intestinalis on germination and root development in the model land plant Arabidopsis thaliana. Ulva extract concentrations above 0.1% inhibited Arabidopsis germination and root growth. Ulva extract <0.1% stimulated root growth. All concentrations of Ulva extract inhibited lateral root formation. An abscisic-acid-insensitive mutant, abi1, showed altered sensitivity to germination- and root growth-inhibition. Ethylene- and cytokinin-insensitive mutants were partly insensitive to germination-inhibition. This suggests that different mechanisms mediate each effect of Ulva extract on early Arabidopsis development and that multiple hormones contribute to germination-inhibition. Elemental analysis showed that Ulva contains high levels of Aluminium ions (Al³⁺). Ethylene and cytokinin have been suggested to function in Al³⁺-mediated root growth inhibition: our data suggest that if Ulva Al³⁺ levels inhibit root growth, this is via a novel mechanism. We suggest algal extracts should be used cautiously as fertilisers, as the inhibitory effects on early development may outweigh any benefits if the concentration of extract is too high.

The drnf1 Gene from the Drought-Adapted Cyanobacterium Nostoc flagelliforme Improved Salt Tolerance in Transgenic Synechocystis and Arabidopsis Plant

Environmental abiotic stresses are limiting factors for less tolerant organisms, including soil plants. Abiotic stress tolerance-associated genes from prokaryotic organisms are supposed to have a bright prospect for transgenic application. The drought-adapted cyanobacterium Nostoc flagelliforme is arising as a valuable prokaryotic biotic resource for gene excavation. In this study, we evaluated the salt-tolerant function and application potential of a candidate gene drnf1 from N. flagelliforme, which contains a P-loop NTPase (nucleoside-triphosphatase) domain, through heterologous expression in two model organisms Synechocystis sp. PCC 6803 and Arabidopsis thaliana. It was found that DRNF1 could confer significant salt tolerance in both transgenic organisms. In salt-stressed transgenic Synechocystis, DRNF1 could enhance the respiration rate; slow-down the accumulation of exopolysaccharides; up-regulate the expression of salt tolerance-related genes at a higher level, such as those related to glucosylglycerol synthesis, Na⁺/H⁺ antiport, and sugar metabolism; and maintain a better K⁺/Na⁺ homeostasis, as compared to the wild-type strain. These results imply that DRNF1 could facilitate salt tolerance by affecting the respiration metabolism and indirectly regulating the expression of important salt-tolerant genes. Arabidopsis was employed to evaluate the salt tolerance-conferring potential of DRNF1 in plants. The results show that it could enhance the seed germination and shoot growth of transgenic plants under saline conditions. In general, a novel prokaryotic salt-tolerant gene from N. flagelliforme was identified and characterized in this study, enriching the candidate gene pool for genetic engineering in plants.

Emerging tools, concepts and ideas to track the modulator genes underlying plant drought adaptive traits: An overview

Crop vulnerability to multiple abiotic stresses is increasing at an alarming rate in the current global climate change scenario, especially drought. Crop improvement for adaptive adjustments to accomplish stress tolerance requires a comprehensive understanding of the key contributory processes. This requires the identification and careful analysis of the critical morpho-physiological plant attributes and their genetic control. In this review we try to discuss the crucial traits underlying drought tolerance and the various modes followed to understand their molecular level regulation. Plant stress biology is progressing into new dimensions and a conscious attempt has been made to traverse through the various approaches and checkpoints that would be relevant to tackle drought stress limitations for sustainable crop production.

Spt-Ada-Gcn5-Acetyltransferase (SAGA) Complex in Plants: Genome Wide Identification, Evolutionary Conservation and Functional Determination

The recruitment of RNA polymerase II on a promoter is assisted by the assembly of basal transcriptional machinery in eukaryotes. The Spt-Ada-Gcn5-Acetyltransferase (SAGA) complex plays an important role in transcription regulation in eukaryotes. However, even in the advent of genome sequencing of various plants, SAGA complex has been poorly defined for their components and roles in plant development and physiological functions. Computational analysis of Arabidopsis thaliana and Oryza sativa genomes for SAGA complex resulted in the identification of 17 to 18 potential candidates for SAGA subunits. We have further classified the SAGA complex based on the conserved domains. Phylogenetic analysis revealed that the SAGA complex proteins are evolutionary conserved between plants, yeast and mammals. Functional annotation showed that they participate not only in chromatin remodeling and gene regulation, but also in different biological processes, which could be indirect and possibly mediated via the regulation of gene expression. The in silico expression analysis of the SAGA components in Arabidopsis and O. sativa clearly indicates that its components have a distinct expression profile at different developmental stages. The co-expression analysis of the SAGA components suggests that many of these subunits co-express at different developmental stages, during hormonal interaction and in response to stress conditions. Quantitative real-time PCR analysis of SAGA component genes further confirmed their expression in different plant tissues and stresses. The expression of representative salt, heat and light inducible genes were affected in mutant lines of SAGA subunits in Arabidopsis. Altogether, the present study reveals expedient evidences of involvement of the SAGA complex in plant gene regulation and stress responses.

The Arabidopsis RNA-binding protein AtRGGA regulates tolerance to salt and drought stress

Salt and drought stress severely reduce plant growth and crop productivity worldwide. The identification of genes underlying stress response and tolerance is the subject of intense research in plant biology. Through microarray analyses, we previously identified in potato (Solanum tuberosum) StRGGA, coding for an Arginine Glycine Glycine (RGG) box-containing RNA-binding protein, whose expression was specifically induced in potato cell cultures gradually exposed to osmotic stress. Here, we show that the Arabidopsis (Arabidopsis thaliana) ortholog, AtRGGA, is a functional RNA-binding protein required for a proper response to osmotic stress. AtRGGA gene expression was up-regulated in seedlings after long-term exposure to abscisic acid (ABA) and polyethylene glycol, while treatments with NaCl resulted in AtRGGA down-regulation. AtRGGA promoter analysis showed activity in several tissues, including stomata, the organs controlling transpiration. Fusion of AtRGGA with yellow fluorescent protein indicated that AtRGGA is localized in the cytoplasm and the cytoplasmic perinuclear region. In addition, the rgga knockout mutant was hypersensitive to ABA in root growth and survival tests and to salt stress during germination and at the vegetative stage. AtRGGA-overexpressing plants showed higher tolerance to ABA and salt stress on plates and in soil, accumulating lower levels of proline when exposed to drought stress. Finally, a global analysis of gene expression revealed extensive alterations in the transcriptome under salt stress, including several genes such as ASCORBATE PEROXIDASE2, GLUTATHIONE S-TRANSFERASE TAU9, and several SMALL AUXIN UPREGULATED RNA-like genes showing opposite expression behavior in transgenic and knockout plants. Taken together, our results reveal an important role of AtRGGA in the mechanisms of plant response and adaptation to stress.

Toward Coalescing Gene Expression and Function with QTLs of Water-Deficit Stress in Cotton

Cotton exhibits moderately high vegetative tolerance to water-deficit stress but lint production is restricted by the available rainfed and irrigation capacity. We have described the impact of water-deficit stress on the genetic and metabolic control of fiber quality and production. Here we examine the association of tentative consensus sequences (TCs) derived from various cotton tissues under irrigated and water-limited conditions with stress-responsive QTLs. Three thousand sixteen mapped sequence-tagged-sites were used as anchored targets to examine sequence homology with 15,784 TCs to test the hypothesis that putative stress-responsive genes will map within QTLs associated with stress-related phenotypic variation more frequently than with other genomic regions not associated with these QTLs. Approximately 1,906 of 15,784 TCs were mapped to the consensus map. About 35% of the annotated TCs that mapped within QTL regions were genes involved in an abiotic stress response. By comparison, only 14.5% of the annotated TCs mapped outside these QTLs were classified as abiotic stress genes. A simple binomial probability calculation of this degree of bias being observed if QTL and non-QTL regions are equally likely to contain stress genes was P (x ≥ 85) = 7.99  × 10(-15). These results suggest that the QTL regions have a higher propensity to contain stress genes.

Composition of the SAGA complex in plants and its role in controlling gene expression in response to abiotic stresses

Protein complexes involved in epigenetic regulation of transcription have evolved as molecular strategies to face environmental stress in plants. SAGA (Spt-Ada-Gcn5 Acetyltransferase) is a transcriptional co-activator complex that regulates numerous cellular processes through the coordination of multiple post-translational histone modifications, including acetylation, deubiquitination, and chromatin recognition. The diverse functions of the SAGA complex involve distinct modules that are highly conserved between yeast, flies, and mammals. In this review, the composition of the SAGA complex in plants is described and its role in gene expression regulation under stress conditions summarized. Some of these proteins are likely involved in the regulation of the inducible expression of genes under light, cold, drought, salt, and iron stress, although the functions of several of its components remain unknown.

TAF13 interacts with PRC2 members and is essential for Arabidopsis seed development

TBP-Associated Factors (TAFs) are components of complexes like TFIID, TFTC, SAGA/STAGA and SMAT that are important for the activation of transcription, either by establishing the basic transcription machinery or by facilitating histone acetylation. However, in Drosophila embryos several TAFs were shown to be associated with the Polycomb Repressive Complex 1 (PRC1), even though the role of this interaction remains unclear. Here we show that in Arabidopsis TAF13 interacts with MEDEA and SWINGER, both members of a plant variant of Polycomb Repressive Complex 2 (PRC2). PRC2 variants play important roles during the plant life cycle, including seed development. The taf13 mutation causes seed defects, showing embryo arrest at the 8-16 cell stage and over-proliferation of the endosperm in the chalazal region, which is typical for Arabidopsis PRC2 mutants. Our data suggest that TAF13 functions together with PRC2 in transcriptional regulation during seed development.

Increasing nitric oxide content in Arabidopsis thaliana by expressing rat neuronal nitric oxide synthase resulted in enhanced stress tolerance

Nitric oxide (NO) plays essential roles in many physiological and developmental processes in plants, including biotic and abiotic stresses, which have adverse effects on agricultural production. However, due to the lack of findings regarding nitric oxide synthase (NOS), many difficulties arise in investigating the physiological roles of NO in vivo and thus its utilization for genetic engineering. Here, to explore the possibility of manipulating the endogenous NO level, rat neuronal NOS (nNOS) was expressed in Arabidopsis thaliana. The 35S::nNOS plants showed higher NOS activity and accumulation of NO using the fluorescent probe 3-amino, 4-aminomethyl-2', 7'-difluorescein, diacetate (DAF-FM DA) assay and the hemoglobin assay. Compared with the wild type, the 35S::nNOS plants displayed improved salt and drought tolerance, which was further confirmed by changes in physiological parameters including reduced water loss rate, reduced stomatal aperture, and altered proline and malondialdehyde content. Quantitative real-time PCR analyses revealed that the expression of several stress-regulated genes was up-regulated in the transgenic lines. Furthermore, the transgenic lines also showed enhanced disease resistance against Pseudomonas syringae pv. tomato (Pst) DC3000 by activating the expression of defense-related genes. In addition, we found that the 35S::nNOS lines flowered late by regulating the expression of CO, FLC and LFY genes. Together, these results demonstrated that it is a useful strategy to exploit the roles of plant NO in various processes by the expression of rat nNOS. The approach may also be useful for genetic engineering of crops with increased environmental adaptations.

Reversible male sterility in eggplant (Solanum melongena L.) by artificial microRNA-mediated silencing of general transcription factor genes

Since decades, plant male sterility is considered a powerful tool for biological containment to minimize unwanted self-pollination for hybrid seed production. Furthermore, prevention of pollen dispersal also answers to concerns regarding transgene flow via pollen from Genetically Modified (GM) crops to traditional crop fields or wild relatives. We induced male sterility by suppressing endogenous general transcription factor genes, TAFs, using anther-specific promoters combined with artificial microRNA (amiRNA) technology (Schwab et al., 2006). The system was made reversible by the ethanol inducible expression of an amiRNA-insensitive form of the target gene. We provide proof of concept in eggplant, a cultivated crop belonging to the Solanaceae family that includes many important food crops. The transgenic eggplants that we generated are completely male sterile and fertility can be fully restored by short treatments with ethanol, confirming the efficiency but also the reliability of the system in view of open field cultivation. By combining this system with induced parthenocarpy (Rotino et al., 1997), we provide a novel example of complete transgene containment in eggplant, which enables biological mitigation measures for the benefit of coexistence or biosafety purposes for GM crop cultivation.

The analysis of an Arabidopsis triple knock-down mutant reveals functions for MBF1 genes under oxidative stress conditions

Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc-) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen peroxide and methyl viologen revealed that the abc- mutant was more sensitive to oxidative stress. The triple knock-down mutant, abc- was also sensitive to osmotic stress mediated by high concentrations of sorbitol. Furthermore, the abc- phenotype was partially or completely rescued by AtMBF1c cDNA over-expression (abc- +c) depending on physiological and developmental conditions. AtMBF1s regulate the expression of ABR1, which is a member of the ethylene-response factor family and acts as ABA repressor. Thus, we conclude that AtMBF1 gene family may function as a regulatory component of the cross-talk node between ethylene, ABA and stress signal pathways. Furthermore, higher levels of a HSP70 mRNA and an immunoreactive HSP70 protein were detected in the abc- mutant. The participation of MBF1c as a possible negative regulator of HSP genes was discussed.

The disturbance of small RNA pathways enhanced abscisic acid response and multiple stress responses in Arabidopsis

The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. To gain more insights into ABA signalling, a population of chemical-inducible activation-tagged Arabidopsis mutants was screened on the basis of the ABA effect on the inhibition of seed germination. Two novel ABA supersensitive mutants ABA supersensitive during germination1 (absg1) and absg2 were characterized as alleles of Dicer-like1 (DCL1) and HEN1, respectively, as microRNA biogenesis genes, and accordingly, these two mutants were renamed dcl1-11 and hen1-16. The dcl1-11 mutant was an ABA hypersensitive mutant for seed germination and root growth. Reverse transcriptase polymerase chain reaction assays revealed that the expression of ABA- and stress-responsive genes was increased in dcl1-11, as compared with the wild type (WT). Furthermore, the germination assay showed that dcl1-11 was also more sensitive to salt and osmotic stress. The hen1-16 mutant also showed supersensitive to ABA during seed germination. Further analysis showed that, among the microRNA biogenesis genes, all the other mutants were not only enhanced in sensitivity to ABA, salt and osmotic stress, but also enhanced the expression of ABA-responsive genes. In addition to the mutants in the microRNA biogenesis, the interruption of the production of crucial components of other small RNA pathways such as dcl2, dcl3 and dcl4 also caused ABA supersensitive during germination.

Yeast two-hybrid map of Arabidopsis TFIID

General transcription factor IID (TFIID) is a multisubunit protein complex involved in promoter recognition and is fundamental to the nucleation of the RNA polymerase II transcriptional preinitiation complex. TFIID is comprised of the TATA binding protein (TBP) and 12-15 TBP-associated factors (TAFs). While general transcription factors have been extensively studied in metazoans and yeast, little is known about the details of their structure and function in the plant kingdom. This work represents the first attempt to compare the structure of a plant TFIID complex with that determined for other organisms. While no TAF3 homolog has been observed in plants, at least one homolog has been identified for each of the remaining 14 TFIID subunits, including both TAF14 and TAF15 which have previously been shown to be unique to either yeast or humans. The presence of both TAFs 14 and 15 in plants suggests ancient roles for these proteins that were lost in metazoans and fungi, respectively. Yeast two-hybrid interaction assays resulted in a total of 65 binary interactions between putative subunits of Arabidopsis TFIID, including 26 contacts unique to plants. The interaction matrix of Arabidopsis TAFs is largely consistent with the three-lobed topological map for yeast TFIID, which suggests that the structure and composition of TFIID have been highly conserved among eukaryotes.

Temporary expression of the TAF10 gene and its requirement for normal development of Arabidopsis thaliana

TAF10 is one of the TATA box-binding protein (TBP)-associated factors (TAFs) which constitute a TFIID with a TBP. Initially most TAFs were thought to be necessary for accurate transcription initiation from a broad group of core promoters. However, it was recently revealed that several TAFs are expressed in limited tissues during animal embryogenesis, and are indispensable for normal development of the tissues. They are called 'selective' TAFs. In plants, however, little is known as to these 'selective' TAFs and their function. Here we isolated the Arabidopsis thaliana TAF10 gene (atTAF10), which is a single gene closely related to the TAF10 genes of other organisms. atTAF10 was expressed transiently during the development of several organs such as lateral roots, rosette leaves and most floral organs. Such an expression pattern was clearly distinct from that of Arabidopsis Rpb1, which encodes a component of RNA polymerase II, suggesting that atTAF10 functions in not only general transcription but also the selective expression of a subset of genes. In a knockdown mutant of atTAF10, we observed several abnormal phenotypes involved in meristem activity and leaf development, suggesting that atTAF10 is concerned in pleiotropic, but selected morphological events in Arabidopsis. These results clearly demonstrate that TAF10 is a 'selective' TAF in plants, providing a new insight into the function of TAFs in plants.