ARL6IP1 mediates small-molecule-induced alleviation of Alzheimer pathology through FXR1-dependent BACE1 translation initiation.

Exploring the potential lead compounds for Alzheimer's disease (AD) remains one of the challenging tasks. Here, we report that the plant extract conophylline (CNP) impeded amyloidogenesis by preferentially inhibiting BACE1 translation via the 5' untranslated region (5'UTR) and rescued cognitive decline in an animal model of APP/PS1 mice. ADP-ribosylation factor-like protein 6-interacting protein 1 (ARL6IP1) was then found to mediate the effect of CNP on BACE1 translation, amyloidogenesis, glial activation, and cognitive function. Through analysis of the 5'UTR-targetd RNA-binding proteins by RNA pulldown combined with LC-MS/MS, we found that FMR1 autosomal homolog 1 (FXR1) interacted with ARL6IP1 and mediated CNP-induced reduction of BACE1 by regulating the 5'UTR activity. Without altering the protein levels of ARL6IP1 and FXR1, CNP treatment promoted ARL6IP1 interaction with FXR1 and inhibited FXR1 binding to the 5'UTR both in vitro and in vivo. Collectively, CNP exhibited a therapeutic potential for AD via ARL6IP1. Through pharmacological manipulation, we uncovered a dynamic interaction between FXR1 and the 5'UTR in translational control of BACE1, adding to the understanding of the pathophysiology of AD.

The BEL1-like homeodomain protein OsBLH4 regulates rice plant height, grain number, and heading date by repressing the expression of OsGA2ox1.

Gibberellins (GAs) play crucial roles in regulating plant architecture and grain yield of crops. In rice, the inactivation of endogenous bioactive GAs and their precursors by GA 2-oxidases (GA2oxs) regulates stem elongation and reproductive development. However, the regulatory mechanisms of GA2ox gene expression, especially in rice reproductive organs, are unknown. The BEL1-like homeodomain protein OsBLH4, a negative regulatory factor for the rice OsGA2ox1 gene, was identified in this study. Loss of OsBLH4 function results in decreased bioactive GA levels and pleiotropic phenotypes, including reduced plant height, decreased grain number per panicle, and delayed heading date, as also observed in OsGA2ox1-overexpressing plants. Consistent with the mutant phenotype, OsBLH4 was predominantly expressed in shoots and young spikelets; its encoded protein was exclusively localized in the nucleus. Molecular analysis demonstrated that OsBLH4 directly bound to the promoter region of OsGA2ox1 to repress its expression. Genetic assays revealed that OsBLH4 acts upstream of OsGA2ox1 to control rice plant height, grain number, and heading date. Taken together, these results indicate a crucial role for OsBLH4 in regulating rice plant architecture and yield potential via regulation of bioactive GA levels, and provide a potential strategy for genetic improvements of rice.

PhasiHunter: a robust phased siRNA regulatory cascade mining tool based on multiple reference sequences.

SUMMARY: In recent years, phased small interfering RNA has been found to play crucial roles in many biological processes in plants. However, efficiently predicting phasiRNA regulatory cascades with computational methods is still challenging. Here, we introduce PhasiHunter, a phasiRNA regulatory network prediction tool that has several distinctive features compared to existing tools: (i) PhasiHunter employs two major phasiRNA prediction algorithms, namely phase score and hypergeometric distribution-based methods, to ensure the integrity and accuracy of prediction; (ii) PhasiHunter can identify phasiRNAs and their regulatory networks based on multiple reference sequences and the predicted results can be automatically integrated; (iii) PhasiHunter can efficiently identify the phasiRNAs generated through alternative splicing events; and (iv) the excellent data structure and parallel computing architecture allow PhasiHunter to predict phasiRNAs and their regulatory pathways with high efficiency. AVAILABILITY AND IMPLEMENTATION: PhasiHunter is an open-source tool that is available at https://github.com/HuangLab-CBI/PhasiHunter.

The laterodorsal tegmentum-ventral tegmental area circuit controls depression-like behaviors by activating ErbB4 in DA neurons.

Dopamine (DA) neurons in the ventral tegmental area (VTA) are critical to coping with stress. However, molecular mechanisms regulating their activity and stress-induced depression were not well understood. We found that the receptor tyrosine kinase ErbB4 in VTA was activated in stress-susceptible mice. Deleting ErbB4 in VTA or in DA neurons, or chemical genetic inhibition of ErbB4 kinase activity in VTA suppressed the development of chronic social defeat stress (CSDS)-induced depression-like behaviors. ErbB4 activation required the expression of NRG1 in the laterodorsal tegmentum (LDTg); LDTg-specific deletion of NRG1 inhibited depression-like behaviors. NRG1 and ErbB4 suppressed potassium currents of VTA DA neurons and increased their firing activity. Finally, we showed that acute inhibition of ErbB4 after stress attenuated DA neuron hyperactivity and expression of depression-like behaviors. Together, these observations demonstrate a critical role of NRG1-ErbB4 signaling in regulating depression-like behaviors and identify an unexpected mechanism by which the LDTg-VTA circuit regulates the activity of DA neurons.

KDM4B down-regulation facilitated breast cancer cell stemness via PHGDH upregulation in H3K36me3-dependent manner.

Despite recent advances have been made in clinical treatments of breast cancer, the general prognosis of patients remains poor. Therefore, it is imperative to develop a more effective therapeutic strategy. Lysine demethylase 4B (KDM4B) has been reported to participate in breast cancer development recently, but its exact biological role in breast cancer remains unclear. Here, we observed that KDM4B was down-regulated in human primary BRCA tissues and the low levels of KDM4B expression were correlated with poor survival. Gain- and loss-of-function experiments showed that KDM4B inhibited the proliferation and metastasis of breast cancer cells. Besides, knockdown of KDM4B promoted the epithelial-mesenchymal transition (EMT) and cell stemness in breast cancer cells. Mechanistically, KDM4B down-regulates PHGDH by decreasing the enrichment of H3K36me3 on the promoter region of PHGDH. Knockdown of PHGDH could significantly reversed proliferation, migration, EMT, and cell stemness induced by KDM4B silencing in breast cancer cells. Collectively, we propose a model for a KDM4B/PHGDH axis that provides novel insight into breast cancer development, which may serve as a potential factor for predicting prognosis and a therapeutic target for breast cancer.

Genome-Wide Association Study Identifies Rice Panicle Blast-Resistant Gene Pb4 Encoding a Wall-Associated Kinase.

Rice blast is one of the most devastating diseases, causing a significant reduction in global rice production. Developing and utilizing resistant varieties has proven to be the most efficient and cost-effective approach to control blasts. However, due to environmental pressure and intense pathogenic selection, resistance has rapidly broken down, and more durable resistance genes are being discovered. In this paper, a novel wall-associated kinase (WAK) gene, Pb4, which confers resistance to rice blast, was identified through a genome-wide association study (GWAS) utilizing 249 rice accessions. Pb4 comprises an N-terminal signal peptide, extracellular GUB domain, EGF domain, EGF-Ca2+ domain, and intracellular Ser/Thr protein kinase domain. The extracellular domain (GUB domain, EGF domain, and EGF-Ca2+ domain) of Pb4 can interact with the extracellular domain of CEBiP. Additionally, its expression is induced by chitin and polygalacturonic acid. Furthermore, transgenic plants overexpressing Pb4 enhance resistance to rice blast. In summary, this study identified a novel rice blast-resistant gene, Pb4, and provides a theoretical basis for understanding the role of WAKs in mediating rice resistance against rice blast disease.

Potassium transporter OsHAK9 regulates seed germination under salt stress by preventing gibberellin degradation through mediating OsGA2ox7 in rice.

Soil salinity has a major impact on rice seed germination, severely limiting rice production. Herein, a rice germination defective mutant under salt stress (gdss) was identified by using chemical mutagenesis. The GDSS gene was detected via MutMap and shown to encode potassium transporter OsHAK9. Phenotypic analysis of complementation and mutant lines demonstrated that OsHAK9 was an essential regulator responsible for seed germination under salt stress. OsHAK9 is highly expressed in germinating seed embryos. Ion contents and non-invasive micro-test technology results showed that OsHAK9 restricted K+ efflux in salt-exposed germinating seeds for the balance of K+/Na+. Disruption of OsHAK9 significantly reduced gibberellin 4 (GA4) levels, and the germination defective phenotype of oshak9a was partly rescued by exogenous GA3 treatment under salt stress. RNA sequencing (RNA-seq) and real-time quantitative polymerase chain reaction analysis demonstrated that the disruption of OsHAK9 improved the GA-deactivated gene OsGA2ox7 expression in germinating seeds under salt stress, and the expression of OsGA2ox7 was significantly inhibited by salt stress. Null mutants of OsGA2ox7 created using clustered, regularly interspaced, short palindromic repeat (CRISPR)/CRISPR-associated nuclease 9 approach displayed a dramatically increased seed germination ability under salt stress. Overall, our results highlight that OsHAK9 regulates seed germination performance under salt stress involving preventing GA degradation by mediating OsGA2ox7, which provides a novel clue about the relationship between GA and OsHAKs in rice.

The phosphoproteomic and interactomic landscape of qGL3/OsPPKL1-mediated brassinosteroid signaling in rice.

Oryza sativa L. (rice) is one of the most important crops in the world, and grain size is a major component determining rice yield. Recent studies have identified a number of grain size regulators, which are involved in phytohormone signaling, G protein signaling, the mitogen-activated protein kinase signaling pathway, the ubiquitin-proteasome pathway or transcriptional regulation. In a previous study, we cloned qGL3/OsPPKL1 encoding a rice protein phosphatase that negatively modulates brassinosteroid (BR) signaling and grain length. Here, to further explore the qGL3-mediated BR signaling network, we performed phosphoproteomic screenings using two pairs of rice materials: the indica rice cultivar 9311 and its near-isogenic line NILqgl3 and the japonica rice cultivar Dongjin and its qGL3 knockout mutant m-qgl3. Together with qGL3-interacting proteins, we constructed the qGL3-mediated network, which reveals the relationships between BR signaling and other critical signaling pathways. Transgenic plants of these network components showed BR-related alterations in plant architecture. From this network, we validated a qGL3-interacting protein, O. sativa VERNALIZATION INSENSITIVE 3-LIKE 1 (OsVIL1), and demonstrated that qGL3 dephosphorylates OsVIL1 to modulate BR signaling. The qGL3-dependent network uncovered in this study increases our understanding of BR signaling and provides a profound foundation for addressing how BR modulates plant architecture in rice.

Brassinosteroids is involved in methane-induced adventitious root formation via inducing cell wall relaxation in marigold.

BACKGROUND: Methane (CH4) and brassinosteroids (BRs) are important signaling molecules involved in a variety of biological processes in plants. RESULTS: Here, marigold (Tagetes erecta L. 'Marvel') was used to investigate the role and relationship between CH4 and BRs during adventitious root (AR) formation. The results showed a dose-dependent effect of CH4 and BRs on rooting, with the greatest biological effects of methane-rich water (MRW, CH4 donor) and 2,4-epibrassinolide (EBL) at 20% and 1 µmol L- 1, respectively. The positive effect of MRW on AR formation was blocked by brassinoazole (Brz, a synthetic inhibitor of EBL), indicating that BRs might be involved in MRW-regulated AR formation. MRW promoted EBL accumulation during rooting by up-regulating the content of campestanol (CN), cathasterone (CT), and castasterone (CS) and the activity of Steroid 5α-reductase (DET2), 22α-hydroxylase (DWF4), and BR-6-oxidase (BR6ox), indicating that CH4 could induce endogenous brassinolide (BR) production during rooting. Further results showed that MRW and EBL significantly down-regulated the content of cellulose, hemicellulose and lignin during rooting and significantly up-regulated the hydrolase activity, i.e. cmcase, xylanase and laccase. In addition, MRW and EBL also significantly promoted the activity of two major cell wall relaxing factors, xyloglucan endotransglucosylase/hydrolase (XTH) and peroxidase, which in turn promoted AR formation. While, Brz inhibited the role of MRW on these substances. CONCLUSIONS: BR might be involved in CH4-promoted AR formation by increasing cell wall relaxation.

The transcription factor OsMYBc and an E3 ligase regulate expression of a K+ transporter during salt stress.

Sodium (Na+) and potassium (K+) homeostasis is essential for plant survival in saline soils. A member of the High-Affinity K+ Transporter (HKT) family in rice (Oryza sativa), OsHKT1;1, is a vital regulator of Na+ exclusion from shoots and is bound by a MYB transcription factor (OsMYBc). Here, we generated transgenic rice lines in the oshkt1;1 mutant background for genetic complementation using genomic OsHKT1;1 containing a native (Com) or mutated (mCom) promoter that cannot be bound by OsMYBc. In contrast to wild-type (WT) or Com lines, the mCom lines were not able to recover the salt-sensitive phenotype of oshkt1;1. The OsMYBc-overexpressing plants were more tolerant to salt stress than WT plants. A yeast two-hybrid screen using the OsMYBc N-terminus as bait identified a rice MYBc stress-related RING finger protein (OsMSRFP). OsMSRFP is an active E3 ligase that ubiquitinated OsMYBc in vitro and mediated 26S proteasome-mediated degradation of OsMYBc under semi-in vitro and in vivo conditions. OsMSRFP attenuated OsMYBc-mediated OsHKT1;1 expression, and knockout of OsMSRFP led to rice salt tolerance. These findings uncover a regulatory mechanism of salt response that fine-tunes OsHKT1;1 transcription by ubiquitination of OsMYBc.

qGL3/OsPPKL1 induces phosphorylation of 14-3-3 protein OsGF14b to inhibit OsBZR1 function in brassinosteroid signaling.

Brassinosteroids (BRs) play essential roles in regulating plant growth and development, however, gaps still remain in our understanding of the BR signaling network. We previously cloned a grain length quantitative trait locus qGL3, encoding a rice (Oryza sativa L.) protein phosphatase with Kelch-like repeat domain (OsPPKL1), that negatively regulates grain length and BR signaling. To further explore the BR signaling network, we performed phosphoproteomic analysis to screen qGL3-regulated downstream components. We selected a 14-3-3 protein OsGF14b from the phosphoproteomic data for further analysis. qGL3 promoted the phosphorylation of OsGF14b and induced the interaction intensity between OsGF14b and OsBZR1. In addition, phosphorylation of OsGF14b played an important role in regulating nucleocytoplasmic shuttling of OsBZR1. The serine acids (Ser258Ser259) residues of OsGF14b play an essential role in BR-mediated responses and plant development. Genetic and molecular analyses indicated that OsGF14b functions as a negative regulator in BR signaling and represses the transcriptional activation activity of OsBZR1. Collectively, these results demonstrate that qGL3 induces the phosphorylation of OsGF14b, which modulates nucleocytoplasmic shuttling and transcriptional activation activity of OsBZR1, to eventually negatively regulate BR signaling and grain length in rice.

OsBAK2/OsSERK2 expression is repressed by OsBZR1 to modulate brassinosteroid response and grain length in rice.

Brassinosteroids (BRs) are a class of polyhydroxylated steroidal phytohormones that are essential for plant growth and development. Rice BRASSINOSTEROID-INSENSITIVE1 (BRI1)-ASSOCIATED RECEPTOR KINASES (OsBAKs) are plasma membrane-localized receptor kinases belonging to the subfamily of leucine-rich repeat receptor kinases. It has been found that in Arabidopsis, BRs induce the formation of a BRI1-BAK1 heterodimer complex and transmit the cascade signal to BRASSINAZOLE RESISTANT1/bri1-EMS-SUPPRESSOR1 (BZR1/BES1) to regulate BR signaling. Here, in rice (Oryza sativa ssp. japonica), we found that OsBZR1 binds directly to the promoter of OsBAK2, but not OsBAK1, and represses the expression of OsBAK2 to form a BR feedback inhibition loop. Additionally, the phosphorylation of OsBZR1 by OsGSK3 reduced its binding to the OsBAK2 promoter. The osbak2 mutant displays a typical BR-deficiency phenotype and negative modulates the accumulation of OsBZR1. Interestingly, the grain length of the osbak2 mutant was increased whereas in the cr-osbak2/cr-osbzr1 double mutant, the reduced grain length of the cr-osbzr1 mutant was restored, implying that the increased grain length of osbak2 may be due to the rice somatic embryogenesis receptor kinase-dependent pathway. Our study reveals a novel mechanism by which OsBAK2 and OsBZR1 engage in a negative feedback loop to maintain rice BR homeostasis, facilitating a deeper understanding of the BR signaling network and grain length regulation in rice.

Identification of a key locus, qNL3.1, associated with seed germination under salt stress via a genome-wide association study in rice.

KEY MESSAGE: Two causal OsTTL and OsSAPK1 genes of the key locus qNL3.1 significantly associated with seed germination under salt stress were identified via a genome-wide association study, which could improve rice seed germination under salt stress. Rice is a salt-sensitive crop, and its seed germination determines subsequent seedling establishment and yields. In this study, 168 accessions were investigated for the genetic control of seed germination under salt stress based on the germination rate (GR), germination index (GI), time at which 50% germination was achieved (T50) and mean level (ML). Extensive natural variation in seed germination was observed among accessions under salt stress. Correlation analysis showed significantly positive correlations among GR, GI and ML and a negative correlation with T50 during seed germination under salt stress. Forty-nine loci significantly associated with seed germination under salt stress were identified, and seven of these were identified in both years. By comparison, 16 loci were colocated with the previous QTLs, and the remaining 33 loci might be novel. qNL3.1, colocated with qLTG-3, was simultaneously identified with the four indices in two years and might be a key locus for seed germination under salt stress. Analysis of candidate genes showed that two genes, the similar to transthyretin-like protein OsTTL and the serine/threonine protein kinase OsSAPK1, were the causal genes of qNL3.1. Germination tests indicated that both Osttl and Ossapk1 mutants significantly reduced seed germination under salt stress compared to the wild type. Haplotype analysis showed that Hap.1 of OsTTL and Hap.1 of OsSAPK1 genes were excellent alleles, and their combination resulted in high seed germination under salt stress. Eight accessions with elite performance of seed germination under salt stress were identified, which could improve rice seed germination under salt stress.

Neddylation is critical to cortical development by regulating Wnt/ß-catenin signaling.

Wnt signaling plays a critical role in production and differentiation of neurons and undergoes a progressive reduction during cortical development. However, how Wnt signaling is regulated is not well understood. Here we provide evidence for an indispensable role of neddylation, a ubiquitylation-like protein modification, in inhibiting Wnt/ß-catenin signaling. We show that ß-catenin is neddylated; and inhibiting ß-catenin neddylation increases its nuclear accumulation and Wnt/ß-catenin signaling. To test this hypothesis in vivo, we mutated Nae1, an obligative subunit of the E1 for neddylation in cortical progenitors. The mutation leads to eventual reduction in radial glia progenitors (RGPs). Consequently, the production of intermediate progenitors (IPs) and neurons is reduced, and neuron migration is impaired, resulting in disorganization of the cerebral cortex. These phenotypes are similar to those of ß-catenin gain-of-function mice. Finally, suppressing ß-catenin expression is able to rescue deficits of Nae1 mutant mice. Together, these observations identified a mechanism to regulate Wnt/ß-catenin signaling in cortical development.

Maize Genotypes Sensitive and Tolerant to Low Phosphorus Levels Exhibit Different Transcriptome Profiles under Talaromyces purpurogenus Symbiosis and Low-Phosphorous Stress.

Talaromyces purpurogenus, an endophytic fungus, exhibits beneficial effects on plants during plant-fungus interactions. However, the molecular mechanisms underlying plants' responses to T. purpurogenus under low-phosphorous (P) stress are not fully understood. In this study, we investigated the transcriptomic changes in maize with low-P-sensitive (31778) and -tolerant (CCM454) genotypes under low-P stress and its symbiotic interaction with T. purpurogenus. Its colonization enhanced plant growth and facilitated P uptake, particularly in 31778. Transcriptome sequencing revealed that 135 DEGs from CCM454 and 389 from 31778 were identified, and that only 6 DEGs were common. This suggested that CCM454 and 31778 exhibited distinct molecular responses to T. purpurogenus inoculation. GO and KEGG analysis revealed that DEGs in 31778 were associated with nicotianamine biosynthesis, organic acid metabolic process, inorganic anion transport, biosynthesis of various secondary metabolites and nitrogen metabolism. In CCM454, DEGs were associated with anthocyanin biosynthesis, diterpenoid biosynthesis and metabolic process. After T. purpurogenus inoculation, the genes associated with phosphate transporter, phosphatase, peroxidase and high-affinity nitrate transporter were upregulated in 31778, whereas AP2-EREBP-transcription factors were detected at significantly higher levels in CCM454. This study provided insights on the molecular mechanisms underlying plant-endophytic fungus symbiosis and low-P stress in maize with low-P-sensitive and -tolerant genotypes.

Traumatic intestinal ischemic necrosis.

A 71-year-old male patient presented to our emergency department with a 1-day history of abdominal pain after an accidental fall. Laboratory test results were as follows: a white blood cell count of 2.32 × 109/L, blood lactate of 3.0 mmol/L, pH 7.30, calcitonin precursor level of 71.09 ng/ml, and creatinine of 115 umol/L. The abdominal CT revealed: portal vein gas accumulation (PVGA) accompanied by a fluid-air level; pneumatosis cystoides intestinalis (PCI) manifested as multiple gas collections within the wall of the lower small intestine. Based on lowered blood pH and elevated lactate levels, there was a high suspicion of small intestinal ischemic necrosis. Subsequent emergency laparotomy and pathological examination confirmed necrosis of the small intestine.

OsHIPL1, a hedgehog-interacting protein-like 1 protein, increases seed vigour in rice.

The cultivation of rice varieties with high seed vigour is vital for the direct seeding of rice, and the molecular basis of regulation of seed vigour remains elusive. Here, we cloned a new gene OsHIPL1, which encodes hedgehog-interacting protein-like 1 protein as a causal gene of the major QTL qSV3 for rice seed vigour. OsHIPL1 was mainly localized in the plasma membrane and nucleus. RNA sequencing (RNA-seq) revealed that the ABA-related genes were involved in the OsHIPL1 regulation of seed vigour in rice. The higher levels of endogenous ABA were measured in germinating seeds of OsHIPL1 mutants and NIL-qsv3 line compared to IR26 plants, with two up-regulated ABA biosynthesis genes (OsZEP and OsNCED4) and one down-regulated ABA catabolism gene OsABA8ox3. The expression of abscisic acid-insensitive 3 (OsABI3), OsABI4 and OsABI5 was significantly up-regulated in germinating seeds of OsHIPL1 mutants and NIL-qsv3 line compared to IR26 plants. These results indicate that the regulation of seed vigour of OsHIPL1 may be through modulating endogenous ABA levels and altering OsABIs expression during seed germination in rice. Meanwhile, we found that OsHIPL1 interacted with the aquaporin OsPIP1;1, then affected water uptake to promote rice seed germination. Based on analysis of single-nucleotide polymorphism data of rice accessions, we identified a Hap1 haplotype of OsHIPL1 that was positively correlated with seed germination. Our findings showed novel insights into the molecular mechanism of OsHIPL1 on seed vigour.

RiceNCexp: a rice non-coding RNA co-expression atlas based on massive RNA-seq and small-RNA seq data.

Non-coding RNAs (ncRNAs) play important roles in regulating expression of protein-coding genes. Although gene expression databases have emerged in a timely manner, a comprehensive expression database for ncRNAs is still lacking. Herein, we constructed a rice ncRNA co-expression atlas (RiceNCexp), based on 491 RNA-seq and 274 small RNA (sRNA)-seq datasets. RiceNCexp hosts four types of ncRNAs, namely lncRNAs, PHAS genes, miRNAs, and phasiRNAs. RiceNCexp provides comprehensive expression information for rice ncRNAs in 22 tissues/organs, an efficient tau-based mining tool for tissue-specific ncRNAs, and the robust co-expression analysis among ncRNAs or between ncRNAs and protein-coding genes, based on 116 pairs of RNA-seq and sRNA-seq libraries from the same experiments. In summary, RiceNCexp is a user-friendly and comprehensive rice ncRNA co-expression atlas and can be freely accessed at https://cbi.njau.edu.cn/RiceNCexp/.

Identification of OsPK5 involved in rice glycolytic metabolism and GA/ABA balance for improving seed germination via genome-wide association study.

Seed germination plays a pivotal role in the plant life cycle, and its precise regulatory mechanisms are not clear. In this study, 19 quantitative trait loci (QTLs) associated with rice seed germination were identified through genome-wide association studies (GWAS) of the following traits in 2016 and 2017: germination rate (GR) at 3, 5, and 7 days after imbibition (DAI) and germination index (GI). Two major stable QTLs, qSG4 and qSG11.1, were found to be associated with GR and GI over 2 continuous years. Furthermore, OsPK5, encoding a pyruvate kinase, was shown to be a crucial regulator of seed germination in rice, and might be a causal gene of the key QTL qSG11.1, on chromosome 11. Natural variation in OsPK5 function altered the activity of pyruvate kinase. The disruption of OsPK5 function resulted in slow germination and seedling growth during seed germination, blocked glycolytic metabolism, caused glucose accumulation, decreased energy levels, and affected the GA/ABA balance. Taken together, our results provide novel insights into the roles of OsPK5 in seed germination, and facilitate its application in rice breeding to improve seed vigour.

Rice qGL3/OsPPKL1 Functions with the GSK3/SHAGGY-Like Kinase OsGSK3 to Modulate Brassinosteroid Signaling.

Brassinosteroids (BRs) are steroid hormones that play essential roles in plant growth and development. We previously cloned qGL3, a major quantitative trait locus regulating grain length in rice (Oryza sativa). The O. sativa japonica var N411 has extra-large grains compared with the O. sativa indica var 9311, and the recessive qgl3 allele from N411 contributes positively to grain length. qGL3 encodes a putative protein phosphatase with Kelch-like repeat domains, an ortholog of Arabidopsis (Arabidopsis thaliana) brassinosteroid-insensitive1 SUPPRESSOR1 (BSU1). BSU1 positively regulates BR signaling, while overexpression of qGL3 induced BR loss-of-function phenotypes. Both qGL3N411 and qGL39311 physically interact with the rice glycogen synthase kinase 3 (GSK3)/SHAGGY-like kinase 3 (OsGSK3), an ortholog of Arabidopsis BR INSENSITIVE2 (BIN2). qGL39311 dephosphorylates OsGSK3, but qGL3N411 lacks this activity. Knocking out OsGSK3 enhances BR signaling and induces nuclear localization of O. sativa BRASSINAZOLE RESISTANT1 (OsBZR1). Unlike the dephosphorylation of BIN2 (which leads to protein degradation) in Arabidopsis, qGL3 dephosphorylates and stabilizes OsGSK3 in rice. These results demonstrate that qGL3 suppresses BR signaling by regulating the phosphorylation and stability of OsGSK3, which modulates OsBZR1 phosphorylation and subcellular distribution. Our study clarifies the role of qGL3 in the regulation of grain length and provides insight into BR signaling, including the differences between rice and Arabidopsis.