RGA1 regulates grain size, rice quality and seed germination in the small and round grain mutant srg5.

BACKGROUND: Generating elite rice varieties with high yield and superior quality is the main goal of rice breeding programs. Key agronomic traits, including grain size and seed germination characteristics, affect the final yield and quality of rice. The RGA1 gene, which encodes the α-subunit of rice G-protein, plays an important role in regulating rice architecture, seed size and abiotic stress responses. However, whether RGA1 is involved in the regulation of rice quality and seed germination traits is still unclear. RESULTS: In this study, a rice mutant small and round grain 5 (srg5), was identified in an EMS-induced rice mutant library. Systematic analysis of its major agronomic traits revealed that the srg5 mutant exhibited a semi-dwarf plant height with small and round grain and reduced panicle length. Analysis of the physicochemical properties of rice showed that the difference in rice eating and cooking quality (ECQ) between the srg5 mutant and its wild-type control was small, but the appearance quality was significantly improved. Interestingly, a significant suppression of rice seed germination and shoot growth was observed in the srg5 mutant, which was mainly related to the regulation of ABA metabolism. RGA1 was identified as the candidate gene for the srg5 mutant by BSA analysis. A SNP at the splice site of the first intron disrupted the normal splicing of the RGA1 transcript precursor, resulting in a premature stop codon. Additional linkage analysis confirmed that the target gene causing the srg5 mutant phenotype was RGA1. Finally, the introduction of the RGA1 mutant allele into two indica rice varieties also resulted in small and round rice grains with less chalkiness. CONCLUSIONS: These results indicate that RGA1 is not only involved in the control of rice architecture and grain size, but also in the regulation of rice quality and seed germination. This study sheds new light on the biological functions of RGA1, thereby providing valuable information for future systematic analysis of the G-protein pathway and its potential application in rice breeding programs.

Gene editing of non-coding regulatory DNA and its application in crop improvement.

The development of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) system has provided precise and efficient strategies to edit target genes and generate transgene-free crops. Significant progress has been made in the editing of protein-coding genes; however, studies on the editing of non-coding DNA with regulatory roles lags far behind. Non-coding regulatory DNAs, including those which can be transcribed into long non-coding RNAs (lncRNAs), and miRNAs, together with cis-regulatory elements (CREs), play crucial roles in regulating plant growth and development. Therefore, the combination of CRISPR/Cas technology and non-coding regulatory DNA has great potential to generate novel alleles that affect various agronomic traits of crops, thus providing valuable genetic resources for crop breeding. Herein, we review recent advances in the roles of non-coding regulatory DNA, attempts to edit non-coding regulatory DNA for crop improvement, and potential application of novel editing tools in modulating non-coding regulatory DNA. Finally, the existing problems, possible solutions, and future applications of gene editing of non-coding regulatory DNA in modern crop breeding practice are also discussed.

Allelic Diversification of the Wx and ALK Loci in Indica Restorer Lines and Their Utilisation in Hybrid Rice Breeding in China over the Last 50 Years.

Hybrid rice technology has been used for more than 50 years, and eating and cooking quality (ECQ) has been a major focus throughout this period. Waxy (Wx) and alkaline denaturation (ALK) genes have received attention owing to their pivotal roles in determining rice characteristics. However, despite significant effort, the ECQ of restorer lines (RLs) has changed very little. By contrast, obvious changes have been seen in inbred rice varieties (IRVs), and the ECQ of IRVs is influenced by Wx, which reduces the proportion of Wxa and increases the proportion of Wxb, leading to a decrease in amylose content (AC) and an increase in ECQ. Meanwhile, ALK is not selected in the same way. We investigated Wx alleles and AC values of sterile lines of female parents with the main mating combinations in widely used areas. The results show that almost all sterile lines were Wxa-type with a high AC, which may explain the low ECQ of hybrid rice. Analysis of hybrid rice varieties and RLs in the last 5 years revealed serious homogenisation among hybrid rice varieties.

Research Progress of Exosomes and Their Forensic Significance.

Exosomes are membranous tiny vesicles secreted by cells, which are widely found in the extracellular matrix and various body fluids and carry a variety of biologically functional molecules such as proteins, lipids, messenger RNA (mRNA) and microRNA (miRNA). Exosomes not only play important biological roles in the field of immunology and oncology, but also have potential application value in the field of forensic medicine. This article reviews the discovery, production and degeneration mechanism, biological functions, isolation and identification methods of exosomes, summarizes the research on exosomes and their significance in the field of forensic science, and discusses their applications in body fluid identification, individual identification, postmortem interval estimation to provide ideas for the application of exosomes in forensic work.

Lysine biofortification in rice by modulating feedback inhibition of aspartate kinase and dihydrodipicolinate synthase.

Lysine is the main limiting essential amino acid (EAA) in the rice seeds, which is a major energy and nutrition source for humans and livestock. In higher plants, the rate-limiting steps in lysine biosynthesis pathway are catalysed by two key enzymes, aspartate kinase (AK) and dihydrodipicolinate synthase (DHDPS), and both are extremely sensitive to feedback inhibition by lysine. In this study, two rice AK mutants (AK1 and AK2) and five DHDPS mutants (DHDPS1-DHDPS5), all single amino acid substitution, were constructed. Their protein sequences passed an allergic sequence-based homology alignment. Mutant proteins were recombinantly expressed in Escherichia coli, and all were insensitive to the lysine analog S-(2-aminoethyl)-l-cysteine (AEC) at concentrations up to 12 mm. The AK and DHDPS mutants were transformed into rice, and free lysine was elevated in mature seeds of transgenic plants, especially those expressing AK2 or DHDPS1, 6.6-fold and 21.7-fold higher than the wild-type (WT) rice, respectively. We then engineered 35A2D1L plants by simultaneously expressing modified AK2 and DHDPS1, and inhibiting rice LKR/SDH (lysine ketoglutaric acid reductase/saccharopine dehydropine dehydrogenase). Free lysine levels in two 35A2D1L transgenic lines were 58.5-fold and 39.2-fold higher than in WT and transgenic rice containing native AK and DHDPS, respectively. Total free amino acid and total protein content were also elevated in 35A2D1L transgenic rice. Additionally, agronomic performance analysis indicated that transgenic lines exhibited normal plant growth, development and seed appearance comparable to WT plants. Thus, AK and DHDPS mutants may be used to improve the nutritional quality of rice and other cereal grains.

Glucan, Water-Dikinase 1 (GWD1), an ideal biotechnological target for potential improving yield and quality in rice.

The source-sink relationship determines the overall agronomic performance of rice. Cloning and characterizing key genes involved in the regulation of source and sink dynamics is imperative for improving rice yield. However, few source genes with potential application in rice have been identified. Glucan, Water-Dikinase 1 (GWD1) is an essential enzyme that plays a pivotal role in the first step of transitory starch degradation in source tissues. In the present study, we successfully generated gwd1 weak mutants by promoter editing using CRISPR/Cas9 system, and also leaf-dominant overexpression lines of GWD1 driven by Osl2 promoter. Analysis of the gwd1 plants indicated that promoter editing mediated down-regulation of GWD1 caused no observable effects on rice growth and development, but only mildly modified its grain transparency and seed germination. However, the transgenic pOsl2::GWD1 overexpression lines showed improvements in multiple key traits, including rice yield, grain shape, rice quality, seed germination and stress tolerance. Therefore, our study shows that GWD1 is not only involved in transitory starch degradation in source tissues, but also plays key roles in the seeds, which is a sink tissue. In conclusion, we find that GWD1 is an ideal biotechnological target with promising potential for the breeding of elite rice cultivars via genetic engineering.

Identification of Structure-Controlling Rice Biosynthesis Enzymes.

The main enzymes controlling the chain-length distributions (CLDs) of starches are starch synthases (SSs), starch branching enzymes (SBEs), and debranching enzymes (DBEs), which have various isoforms, denoted as SSI, SSII-1, etc. Different isozymes dominate the CLD in different ranges of degrees of polymerization (DPs). Models have been developed for the CLDs in terms of the activities of isoforms of these enzymes, in terms of two parameters: ßi, which is the ratio of the activity of SBE to that of SS in set i, and hi, which is the relative activity of SS in that set. These provide good fits to data but without specifying which isozymes are in set i. Here, CLDs for amylopectin and amylose synthesis in rice endosperm are explored. Molecular weight distributions of the different chains formed in 87 rice varieties were obtained using size-exclusion chromatography following enzymatic debranching (converting a complex branched macromolecule to linear polymers), and fitted by the biosynthesis-based models. The mutants of each isoform among tested rice varieties were identified by amino-acid mutations in coding sequences based on the extraction and analysis of whole gene sequences. The significant differences between mutant groups of different isoforms indicate that SSI, SSII-3, SSIII-1, SSIII-2, and SBEI as well as GBSSI (an isozyme of granule-bound starch synthase) belong to the enzymes sets that control amylose biosynthesis. Further, GBSSI is in the enzyme sets that control amylopectin chains. This enables specification of all isozymes and the DP range, which they dominate, over the entire DP range. As the CLD controls many functional properties of rice, this can help breeders target and develop improved rice species.

Genome-Wide Identification and Expression Analysis of OsbZIP09 Target Genes in Rice Reveal Its Mechanism of Controlling Seed Germination.

Seed dormancy and germination are key events in plant development and are critical for crop production, and defects in seed germination or the inappropriate release of seed dormancy cause substantial losses in crop yields. Rice is the staple food for more than half of the world's population, and preharvest sprouting (PHS) is one of the most severe problems in rice production, due to a low level of seed dormancy, especially under warm and damp conditions. Therefore, PHS leads to yield loss and a decrease in rice quality and vitality. We reveal that mutation of OsbZIP09 inhibited rice PHS. Analysis of the expression of OsbZIP09 and its encoded protein sequence and structure indicated that OsbZIP09 is a typical bZIP transcription factor that contains conserved bZIP domains, and its expression is induced by ABA. Moreover, RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) analyses were performed and 52 key direct targets of OsbZIP09 were identified, including OsLOX2 and Late Embryogenesis Abundant (LEA) family genes, which are involved in controlling seed germination. Most of these key targets showed consistent changes in expression in response to abscisic acid (ABA) treatment and OsbZIP09 mutation. The data characterize a number of key target genes that are directly regulated by OsbZIP09 and contribute to revealing the molecular mechanism that underlies how OsbZIP09 controls rice seed germination.

Progress on inheritance and gene cloning for rice grain quality in Jiangsu province.

In China, rice (Oryza sativa L.) is a major cereal crop of great importance maintaining the food security and sustainable agricultural development. Jiangsu is one of the main provinces for rice production. After more than 40 years of development, the yield and quality of rice grain have made great progress. Rice grain quality is a complex trait involving production, processing, marketing and consumption of the grain. In this review, we summarize the progress on the genetic basis of main grain quality traits in the rice variety breeding in Jiangsu province and point out the achievement of each milestone. With a focus on the genetic regulation of grain appearance, eating and cooking quality and nutritional quality, we describe the classic genetic rules and molecular basis of rice grain quality traits and review the function of major genes that regulate corresponding traits. The genetics and improvement of grain quality achieved in Jiangsu province was highlighted on the domestic and international rice breeding programs. In particular, with the advance of breeding conception in terms of functional genomics and genetic regulatory networks, the specific molecular design for grain quality improvement will be the future direction of rice genetic breeding program of Jiangsu Province.

A Connection between Lysine and Serotonin Metabolism in Rice Endosperm.

Cereal endosperms produce a vast array of metabolites, including the essential amino acid lysine (Lys). Enhanced accumulation of Lys has been achieved via metabolic engineering in cereals, but the potential connection between metabolic engineering and Lys fortification is unclear. In mature seeds of engineered High Free Lysine (HFL) rice (Oryza sativa), the endosperm takes on a characteristic dark-brown appearance. In this study, we use an integrated metabolomic and transcriptomic approach combined with functional validation to elucidate the key metabolites responsible for the dark-brown phenotype. Importantly, we found that serotonin biosynthesis was elevated dramatically and closely linked with dark-brown endosperm color in HFL rice. A functional connection between serotonin and endosperm color was confirmed via overexpression of TDC3, a key enzyme of serotonin biosynthesis. Furthermore, we show that both the jasmonate signaling pathway and TDC expression were strongly induced in the late stage of endosperm development of HFL rice, coinciding with serotonin accumulation and dark-brown pigmentation. We propose a model for the metabolic connection between Lys and serotonin metabolism in which elevated 2-aminoadipate from Lys catabolism may play a key role in the connection between the jasmonate signaling pathway, serotonin accumulation, and the brown phenotype in rice endosperm. Our data provide a deeper understanding of amino acid metabolism in rice. In addition, the finding that both Lys and serotonin accumulate in HFL rice grains should promote efforts to create a nutritionally favorable crop.

Abscisic Acid Represses Rice Lamina Joint Inclination by Antagonizing Brassinosteroid Biosynthesis and Signaling.

Leaf angle is a key parameter that determines plant architecture and crop yield. Hormonal crosstalk involving brassinosteroid (BR) plays an essential role in leaf angle regulation in cereals. In this study, we investigated whether abscisic acid (ABA), an important stress-responsive hormone, co-regulates lamina joint inclination together with BR, and, if so, what the underlying mechanism is. Therefore, lamina joint inclination assay and RNA sequencing (RNA-Seq) analysis were performed here. ABA antagonizes the promotive effect of BR on leaf angle. Hundreds of genes responsive to both hormones that are involved in leaf-angle determination were identified by RNA-Seq and the expression of a gene subset was confirmed using quantitative real-time PCR (qRT-PCR). Results from analysis of rice mutants or transgenic lines affected in BR biosynthesis and signaling indicated that ABA antagonizes the effect of BR on lamina joint inclination by targeting the BR biosynthesis gene D11 and BR signaling genes GSK2 and DLT, thus forming a multi-level regulatory module that controls leaf angle in rice. Taken together, our findings demonstrate that BR and ABA antagonistically regulate lamina joint inclination in rice, thus contributing to the elucidation of the complex hormonal interaction network that optimizes leaf angle in rice.

iTRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination.

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR⁻GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

A residue substitution in the plastid ribosomal protein L12/AL1 produces defective plastid ribosome and causes early seedling lethality in rice.

The plastid ribosome is essential for chloroplast biogenesis as well as seedling formation. As the plastid ribosome closely resembles the prokaryotic 70S ribosome, many plastid ribosomal proteins (PRPs) have been identified in higher plants. However, their assembly in the chloroplast ribosome in rice remains unclear. In the present study, we identified a novel rice mutant, albino lethal 1 (al1), from a chromosome segment substitution line population. The al1 mutant displayed an albino phenotype at the seedling stage and did not survive past the three-leaf stage. No other apparent differences in plant morphology were observed in the al1 mutant. The albino phenotype of the al1 mutant was associated with decreased chlorophyll content and abnormal chloroplast morphology. Using fine mapping, AL1 was shown to encode the PRPL12, a protein localized in the chloroplasts of rice, and a spontaneous single-nucleotide mutation (C/T), resulting in a residue substitution from leucine in AL1 to phenylalanine in al1, was found to be responsible for the early seedling lethality. This point mutation is located at the L10 interface feature of the L12/AL1 protein. Yeast two-hybrid analysis showed that there was no physical interaction between al1 and PRPL10. In addition, the mutation had little effect on the transcript abundance of al1, but had a remarkable effect on the protein abundance of al1 and transcript abundance of chloroplast biogenesis-related and photosynthesis-related genes. These results provide a first glimpse into the molecular details of L12's function in rice.

Biofortification of rice with the essential amino acid lysine: molecular characterization, nutritional evaluation, and field performance.

Rice (Oryza sativa L.), a major staple crop worldwide, has limited levels of the essential amino acid lysine. We previously produced engineered rice with increased lysine content by expressing bacterial aspartate kinase and dihydrodipicolinate synthase and inhibiting rice lysine ketoglutarate reductase/saccharopine dehydrogenase activity. However, the grain quality, field performance, and integration patterns of the transgenes in these lysine-enriched lines remain unclear. In the present study, we selected several elite transgenic lines with endosperm-specific or constitutive regulation of the above key enzymes but lacking the selectable marker gene. All target transgenes were integrated into the intragenic region in the rice genome. Two pyramid transgenic lines (High Free Lysine; HFL1 and HFL2) with free lysine levels in seeds up to 25-fold that of wild type were obtained via a combination of the above two transgenic events. We observed a dramatic increase in total free amino acids and a slight increase in total protein content in both pyramid lines. Moreover, the general physicochemical properties were improved in pyramid transgenic rice, but the starch composition was not affected. Field trials indicated that the growth of HFL transgenic rice was normal, except for a slight difference in plant height and grain colour. Taken together, these findings will be useful for the potential commercialization of high-lysine transgenic rice.

Major QTLs reduce the deleterious effects of high temperature on rice amylose content by increasing splicing efficiency of Wx pre-mRNA.

KEY MESSAGE: We discovered four QTLs that maintain proper rice amylose content at high temperature by increasing the splicing efficiency of Wx gene. Amylose content mainly controlled by Wx gene is a key physicochemical property for eating and cooking quality in rice. During the grain filling stage, high temperature can harm rice grain quality by significantly reducing the amylose content in many rice varieties. Here, we provide genetic evidences between Wx gene expression and rice amylose content at high temperature, and identified several quantitative trait loci (QTLs) in this pathway. We performed a genome-wide survey on a set of chromosome segment substitution lines (CSSLs) which carried chromosomal segments from the heat resistant indica 9311 in the heat-sensitive japonica Nipponbare background. Four QTLs, qHAC4, qHAC8a, qHAC8b and qHAC10, which can reduce the deleterious effects of amylose content at high temperature, were identified and mapped to chromosome 4, 8, 8 and 10, respectively. The major QTL qHAC8a, with the highest LOD score of 6.196, was physically mapped to a small chromosome segment (~300 kb). The CSSLs carrying the qHAC8a, qHAC8b and/or qHAC4 from 9311 have the high pre-mRNA splicing efficiency of Wx gene and likely lead to stable amylose content at high temperature. Thus, increasing pre-mRNA processing efficiency of Wx gene could be an important regulation mechanism for maintaining stable amylose content in rice seeds at high temperature. In addition, our results provide a theoretical basis for breeding heat-stable grain in rice.

ABA-mediated regulation of rice grain quality and seed dormancy via the NF-YB1-SLRL2-bHLH144 Module.

Abscisic acid (ABA) plays a crucial role in promoting plant stress resistance and seed dormancy. However, how ABA regulates rice quality remains unclear. This study identifies a key transcription factor SLR1-like2 (SLRL2), which mediates the ABA-regulated amylose content (AC) of rice. Mechanistically, SLRL2 interacts with NF-YB1 to co-regulate Wx, a determinant of AC and rice quality. In contrast to SLR1, SLRL2 is ABA inducible but insensitive to GA. In addition, SLRL2 exhibits DNA-binding activity and directly regulates the expression of Wx, bHLH144 and MFT2. SLRL2 competes with NF-YC12 for interaction with NF-YB1. NF-YB1 also directly represses SLRL2 transcription. Genetic validation supports that SLRL2 functions downstream of NF-YB1 and bHLH144 in regulating rice AC. Thus, an NF-YB1-SLRL2-bHLH144 regulatory module is successfully revealed. Furthermore, SLRL2 regulates rice dormancy by modulating the expression of MFT2. In conclusion, this study revealed an ABA-responsive regulatory cascade that functions in both rice quality and seed dormancy.

Co-Overexpression of Two Key Source Genes, OsBMY4 and OsISA3, Improves Multiple Key Traits of Rice Seeds.

Optimized source-sink interactions are determinants of both rice yield and quality. However, most source genes have not been well studied in rice, a major grain crop. In this study, OsBMY4 and OsISA3, the key ß-amylase and debranching enzymes that control transient starch degradation in rice leaves, were co-overexpressed in rice in order to accelerate starch degradation efficiency and increase the sugar supply for sink organs. Systematic analyses of the transgenic rice indicated that co-overexpression of OsBMY4 and OsISA3 not only promoted rice yield and quality, but also improved seed germination and stress tolerance. Moreover, since the OsBMY4 gene has not been characterized, we generated osbmy4 mutants using CRIPSR/Cas9 gene editing, which helped to reveal the roles of ß-amylase in rice yield and quality. This study demonstrated that specific modulation of the expression of some key source genes improves the source-sink balance and leads to improvements in multiple key traits of rice seeds.

[The effect of compressive stress on the factors for liver regeneration in hepatocytes Chang cell line].

OBJECTIVE: To investigate the effect of compressive stress on the factors for liver regeneration including NF-kappaB, signal transducers and activators of transcription 3 (STATS), c-fos and c-jun in hepatocytes Chang cell line. METHODS: Human hepatocytes Chang cell line were subjected to compressive stress at 1000 microstain or 2000 microstain, expression of NF-kappaB P65, p-STAT3, c-fos and c-jun were detected by Western blot or RT-PCR at 30 min, 1 h, 2 h, 3 h, 4 h, 6 h after application of compressive stress to indicate the priming of hepatocytes proliferation. RESULTS: Enhanced expressions of NF-kappaB P65 and p-STAT3 were observed in hepatocytes under compressive stress indicated by Western blot, the magnitude of compressive stress loaded significantly affected the level of expression of NF-kappaB P65 at 2 h (P = 0.046) and p-STAT3 at 1 h (P = 0.039), the peak of expression of p-STAT3 was at 30 minutes after stress-loading while NF-kappaB P65 was at 1 hour; RT-PCR showed that expression of c-fos was not significantly different between 1000 microstain and 2000 microstain at each time point, and expression of c-jun was significantly different at 30 minutes (P = 0.026), 1 h (P = 0.031), 2 h (P = 0.033) after compressive stress loading. CONCLUSION: These results indicate that compressive stress may play an important role in initiating the process of liver regeneration.

Genes and Their Molecular Functions Determining Seed Structure, Components, and Quality of Rice.

With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

The WRKY transcription factor OsWRKY78 regulates stem elongation and seed development in rice.

WRKY proteins are a large super family of transcriptional regulators primarily involved in various plant physiological programs. In present study, the expression profile and putative function of the WRKY transcriptional factor, WRKY78, in rice were identified. Real-time RT-PCR analysis showed that OsWRKY78 transcript was most abundant in elongating stems though its expression was detected in all the tested organs. The expression profiles were further confirmed by using promoter-GUS analysis in transgenic rice. OsWRKY78::GFP fusion gene transient expression analysis demonstrated that OsWRKY78 targeted to the nuclei of onion epidermal cell. Furthermore, OsWRKY78 RNAi and overexpression transgenic rice lines were generated. Transgenic plants with OsWRKY78 overexpression exhibited a phenotype identical to the wild type, whereas inhibition of OsWRKY78 expression resulted in a semi-dwarf and small kernel phenotype due to reduced cell length in transgenic plants. In addition, a T-DNA insertion mutant line oswrky78 was identified and a phenotype similar to that of RNAi plants was also observed. Grain quality analysis data showed no significant differences, with the exception of minor changes in endosperm starch crystal structure in RNAi plants. Taken together, these results suggest that OsWRKY78 may acts as a stem elongation and seed development regulator in rice.