Dataset Information

Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis.

ABSTRACT: The uppermost internode is one of the fastest elongating organs in rice, and is expected to require an adequate supply of cell-wall materials and enzymes to the cell surface to enhance mechanical strength. Although it has been reported that the phenotype of shortened uppermost internode 1 (sui1) is caused by mutations in PHOSPHATIDYLSERINE SYNTHASE (OsPSS), the underlying mechanism remains unclear. Here we show that the OsPSS-1, as a gene expressed predominantly in elongating cells, regulates post-Golgi vesicle secretion to intercellular spaces. Mutation of OsPSS-1 leads to compromised delivery of CESA4 and secGFP towards the cell surface, resulting in weakened intercellular adhesion and disorganized cell arrangement in parenchyma. The phenotype of sui1-4 is caused largely by the reduction in cellulose contents in the whole plant and detrimental delivery of pectins in the uppermost internode. We found that OsPSS-1 and its potential product PS (phosphatidylserine) localized to organelles associated with exocytosis. These results together suggest that OsPSS-1 plays a potential role in mediating cell expansion by regulating secretion of cell wall components.

SUBMITTER: Ma J

PROVIDER: S-EPMC4824389 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis.

Ma Jin J Cheng Zhijun Z Chen Jun J Shen Jinbo J Zhang Baocai B Ren Yulong Y Ding Yu Y Zhou Yihua Y Zhang Huan H Zhou Kunneng K Wang Jiu-Lin JL Lei Cailin C Zhang Xin X Guo Xiuping X Gao He H Bao Yiqun Y Wan Jian-Min JM

PloS one 20160407 4

The uppermost internode is one of the fastest elongating organs in rice, and is expected to require an adequate supply of cell-wall materials and enzymes to the cell surface to enhance mechanical strength. Although it has been reported that the phenotype of shortened uppermost internode 1 (sui1) is caused by mutations in PHOSPHATIDYLSERINE SYNTHASE (OsPSS), the underlying mechanism remains unclear. Here we show that the OsPSS-1, as a gene expressed predominantly in elongating cells, regulates po ...[more]

PMID: 27055010

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Project description:BackgroundRice (Oryza sativa L.) yield is seriously influenced by panicle exsertion (PE) and the uppermost internode (UI) through panicle enclosure or energy transport during grain-filling stages. We evaluated the traits of PE and UI of 205 rice accessions in two independent environments and performed genome-wide association (GWAS) to explore the key genes controlling PE and UI, which could be used to improve panicle enclosure in rice breeding.ResultsIn this study, extensive genetic variation was found in both PE and UI among the 205 rice accessions, and 10.7% of accessions had panicle enclosure (PE/UI???0). Correlation analysis revealed that PE was significantly positively correlated with 1000-grain weight (1000-GW) but negatively correlated with heading date (HD), and UI was significantly positively correlated with HD but no significantly correlated with 1000-GW. A total of 22 and 24 quantitative trait loci (QTLs) were identified for PE and UI using GWAS, respectively. Eight loci for PE and nine loci for UI were simultaneously detected both in 2015 and in 2016, seven loci had adjacent physical positions between PE and UI, and ten loci for PE and seven loci for UI were located in previously reported QTLs. Further, we identified the CYP734A4 gene, encoding a cytochrome P450 monooxygenase, and the OsLIS-L1 gene, encoding a lissencephaly type-1-like protein, as causal genes for qPE14 and qUI14, and for qPE19, respectively. PE and UI were both significantly shorter in these two genes' mutants than in WT. Allelic Hap.1/2/4 of CYP734A4 and Hap.1/2/4 of OsLIS-L1 increased PE, UI, PE/UI, and 1000-GW, but Hap.3 of CYP734A4 and Hap.3 of OsLIS-L1 reduced them. In addition, six candidate genes were also detected for four key novel loci, qPE16, qPE21, qUI1, and qUI18, that seemed to be related to PE and UI.ConclusionsOur results provide new information on the genetic architecture of PE and UI in rice, confirming that the CYP734A4 and OsLIS-L1 genes participate in PE and UI regulation, which could improve our understanding of the regulatory mechanism of PE and UI for rice breeding in the future.

Project description:To avoid low oxygen, oxygen deficiency or oxygen deprivation, deepwater rice cultivated in flood planes can develop elongated internodes in response to submergence. Knowledge of the gene regulatory networks underlying rapid internode elongation is important for an understanding of the evolution and adaptation of major crops in response to flooding. To elucidate the genetic and molecular basis controlling their deepwater response we used microarrays and performed expression quantitative trait loci (eQTL) and phenotypic QTL (phQTL) analyses of internode samples of 85 recombinant inbred line (RIL) populations of non-deepwater (Taichung 65)- and deepwater rice (Bhadua). After evaluating the phenotypic response of the RILs exposed to submergence, confirming the genotypes of the populations, and generating 188 genetic markers, we identified 10,047 significant eQTLs comprised of 2,902 cis-eQTLs and 7,145 trans-eQTLs and three significant eQTL hotspots on chromosomes 1, 4, and 12 that affect the expression of many genes. The hotspots on chromosomes 1 and 4 located at different position from phQTLs detected in this study and other previous studies. We then regarded the eQTL hotspots as key regulatory points to infer causal regulatory networks of deepwater response including rapid internode elongation. Our results suggest that the downstream regulation of the eQTL hotspots on chromosomes 1 and 4 is independent, and that the target genes are partially regulated by SNORKEL1 and SNORKEL2 genes (SK1/2), key ethylene response factors. Subsequent bioinformatic analyses, including gene ontology-based annotation and functional enrichment analysis and promoter enrichment analysis, contribute to enhance our understanding of SK1/2-dependent and independent pathways. One remarkable observation is that the functional categories related to photosynthesis and light signaling are significantly over-represented in the candidate target genes of SK1/2. The combined results of these investigations together with genetical genomics approaches using structured populations with a deepwater response are also discussed in the context of current molecular models concerning the rapid internode elongation in deepwater rice. This study provides new insights into the underlying genetic architecture of gene expression regulating the response to flooding in deepwater rice and will be an important community resource for analyses on the genetic basis of deepwater responses.

Project description:BACKGROUND:Internode elongation is an important agronomic trait in rice that determines culm length, which is related to lodging, panicle exsertion, and biomass. sui4 (shortened uppermost internode 4) mutants show reduced internode length and a dwarf phenotype due to shortened internodes; the uppermost internode is particularly severely affected. The present study was performed to identify the molecular nature and function of the SUI4 gene during internode elongation. RESULTS:Our previous study showed that the SUI4 gene was mapped to a 1.1-Mb interval on chromosome 7 (Ji et al. 2014). In order to isolate the gene responsible for the sui4 phenotype, genomic DNA resequencing of sui4 mutants and wild-type plants and reciprocal transformation of wild-type and mutant alleles of the putative SUI4 gene was performed. The data revealed that the causative mutation of sui4 was a T to A nucleotide substitution at the microRNA172 binding site of Os07g0235800, and that SUI4 is a new allele of the previously reported gene SUPERNUMERARY BRACT (SNB), which affects flower structure. In order to understand the effect of this mutation on expression of the SUI4/SNB gene, SUI4/SNB native promoter-fuzed GUS transgenics were examined, along with qRT-PCR analysis at various developmental stages. In sui4 mutants, the SUI4/SNB gene was upregulated in the leaves, culms, and panicles, especially when internodes were elongated. In culms, SUI4/SNB was expressed in the nodes and the lower parts of elongating internodes. In order to further explore the molecular nature of SUI4/SNB during internode elongation, RNA-seq and qRT-PCR analysis were performed with RNAs from the culms of sui4 mutants and wild-type plants in the booting stage. The data showed that in sui4 mutants, genes deactivating bioactive gibberellins and cytokinin were upregulated while genes related to cell expansion and cell wall synthesis were downregulated. CONCLUSION:In summary, this paper shows that interaction between SUI4/SNB and microRNA172 could determine internode elongation during the reproductive stage in rice plants. Due to a mutation at the microRNA172 binding site in sui4 mutants, the expression of SUI4/SNB was enhanced, which lowered the activities of cell expansion and cell wall synthesis and consequently resulted in shortened internodes.

Project description:Clade A protein phosphatase 2Cs (PP2CAs) negatively regulate abscisic acid (ABA) signaling. Here, we investigated the functions of OsPP2CAs and their crosstalk with ABA and gibberellic acid (GA) signaling pathways in rice (Oryza sativa). Among the nine OsPP2CAs, OsPP2C08 had the highest amino acid sequence similarity with OsPP2C51, which positively regulates GA signaling in rice seed germination. However, OsPP2C08 was expressed in different tissues (internodes, sheaths, and flowers) compared to OsPP2C51, which was specifically expressed in seeds, and showed much stronger induction under abiotic stress than OsPP2C51. Transgenic rice lines overexpressing OsPP2C08 (OsPP2C08-OX) had a typical ABA-insensitive phenotype in a post-germination assay, indicating that OsPP2C08, as with other OsPP2CAs, negatively regulates ABA signaling. Furthermore, OsPP2C08-OX lines had longer stems than wild-type (WT) plants due to longer internodes, especially between the second and third nodes. Internode cells were also longer in OsPP2C08-OX lines than in the WT. As GA positively regulates plant growth, these results suggest that OsPP2C08 might positively regulate GA biosynthesis. Indeed, the expression levels of GA biosynthetic genes including gibberellin 20-oxidase (OsGA20ox4) and Ent-kaurenoic acid oxidase (OsKAO) were increased in OsPP2C08-OX lines, and we observed that GIBBERELLIN 2-OXIDASE 4 (OsGA2ox4), encoding an oxidase that catalyzes the 2-beta-hydroxylation of several biologically active GAs, was repressed in the OsPP2C08-OX lines based on a transcriptome deep sequencing and RT-qPCR analysis. Furthermore, we compared the accumulation of SLENDER RICE 1 (SLR1), a DELLA protein involved in GA signaling, in OsPP2C08-OX and WT plants, and observed lower levels of SLR1 in the OsPP2C08-OX lines than in the WT. Taken together, our results reveal that OsPP2C08 negatively regulates ABA signaling and positively regulates GA signaling in rice. Our study provides valuable insight into the molecular mechanisms underlying the crosstalk between GA and ABA signaling in rice.

Dataset Information

Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis.

Publications

Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis.

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