1887

Abstract

Two common classes of nitrogen-fixing legume root nodules are those that have determinate or indeterminate meristems, as in Phaseolus bean and pea, respectively. In indeterminate nodules, rhizobia terminally differentiate into bacteroids with endoreduplicated genomes, whereas bacteroids from determinate nodules are less differentiated and can regrow. We used RNA sequencing to compare bacteroid gene expression in determinate and indeterminate nodules using two Rhizobium leguminosarum strains whose genomes differ due to replacement of the symbiosis (Sym) plasmid pRP2 (strain Rlp4292) with pRL1 (strain RlvA34), thereby switching symbiosis hosts from Phaseolus bean (determinate nodules) to pea (indeterminate nodules). Both bacteroid types have gene expression patterns typical of a stringent response, a stressful environment and catabolism of dicarboxylates, formate, amino acids and quaternary amines. Gene expression patterns were indicative that bean bacteroids were more limited for phosphate, sulphate and iron than pea bacteroids. Bean bacteroids had higher levels of expression of genes whose products are predicted to be associated with metabolite detoxification or export. Pea bacteroids had increased expression of genes associated with DNA replication, membrane synthesis and the TCA (tricarboxylic acid) cycle. Analysis of bacteroid-specific transporter genes was indicative of distinct differences in sugars and other compounds in the two nodule environments. Cell division genes were down-regulated in pea but not bean bacteroids, while DNA synthesis was increased in pea bacteroids. This is consistent with endoreduplication of pea bacteroids and their failure to regrow once nodules senesce.

Loading

Article metrics loading...

/content/journal/mgen/10.1099/mgen.0.000254
2019-02-19
2019-10-20
Loading full text...

Full text loading...

/deliver/fulltext/mgen/5/2/mgen000254.html?itemId=/content/journal/mgen/10.1099/mgen.0.000254&mimeType=html&fmt=ahah

References

  1. Masson-Boivin C, Giraud E, Perret X, Batut J. Establishing nitrogen-fixing symbiosis with legumes: how many rhizobium recipes?. Trends Microbiol 2009;17:458–466 [CrossRef][PubMed]
    [Google Scholar]
  2. Oldroyd GE, Murray JD, Poole PS, Downie JA. The rules of engagement in the legume-rhizobial symbiosis. Annu Rev Genet 2011;45:119–144 [CrossRef][PubMed]
    [Google Scholar]
  3. Udvardi M, Poole PS. Transport and metabolism in legume-rhizobia symbioses. Annu Rev Plant Biol 2013;64:781–805 [CrossRef][PubMed]
    [Google Scholar]
  4. Dixon R, Kahn D. Genetic regulation of biological nitrogen fixation. Nat Rev Microbiol 2004;2:621–631 [CrossRef][PubMed]
    [Google Scholar]
  5. Terpolilli JJ, Hood GA, Poole PS. What determines the efficiency of N2-fixing Rhizobium-legume symbioses?. In Poole RK. (editor) Advances in Microbial Physiologyvol. 6 Amsterdam: Academic Press; 2012; pp.325–389
    [Google Scholar]
  6. Mergaert P, Uchiumi T, Alunni B, Evanno G, Cheron A et al. Eukaryotic control on bacterial cell cycle and differentiation in the Rhizobium-legume symbiosis. Proc Natl Acad Sci USA 2006;103:5230–5235 [CrossRef][PubMed]
    [Google Scholar]
  7. Oldroyd GE, Downie JA. Coordinating nodule morphogenesis with rhizobial infection in legumes. Annu Rev Plant Biol 2008;59:519–546 [CrossRef][PubMed]
    [Google Scholar]
  8. Mergaert P, Nikovics K, Kelemen Z, Maunoury N, Vaubert D et al. A novel family in Medicago truncatula consisting of more than 300 nodule-specific genes coding for small, secreted polypeptides with conserved cysteine motifs. Plant Physiol 2003;132:161–173 [CrossRef][PubMed]
    [Google Scholar]
  9. Zhou P, Silverstein KA, Gao L, Walton JD, Nallu S et al. Detecting small plant peptides using SPADA (small peptide alignment discovery application). BMC Bioinformatics 2013;14:335 [CrossRef][PubMed]
    [Google Scholar]
  10. Kato T, Kawashima K, Miwa M, Mimura Y, Tamaoki M et al. Expression of genes encoding late nodulins characterized by a putative signal peptide and conserved cysteine residues is reduced in ineffective pea nodules. Mol Plant Microbe Interact 2002;15:129–137 [CrossRef][PubMed]
    [Google Scholar]
  11. van de Velde W, Zehirov G, Szatmari A, Debreczeny M, Ishihara H et al. Plant peptides govern terminal differentiation of bacteria in symbiosis. Science 2010;327:1122–1126 [CrossRef][PubMed]
    [Google Scholar]
  12. Montiel J, Downie JA, Farkas A, Bihari P, Herczeg R et al. Morphotype of bacteroids in different legumes correlates with the number and type of symbiotic NCR peptides. Proc Natl Acad Sci USA 2017;114:5041–5046 [CrossRef][PubMed]
    [Google Scholar]
  13. Karunakaran R, Ramachandran VK, Seaman JC, East AK, Mouhsine B et al. Transcriptomic analysis of Rhizobium leguminosarum biovar viciae in symbiosis with host plants Pisum sativum and Vicia cracca. J Bacteriol 2009;191:4002–4014 [CrossRef][PubMed]
    [Google Scholar]
  14. Franck S, Franck WL, Birke SR, Chang W-S, Sangurdekar DP et al. Comparative transcriptomic analysis of symbiotic Bradyrhizobium japonicum. Symbiosis 2014;63:123–135 [CrossRef]
    [Google Scholar]
  15. Pessi G, Ahrens CH, Rehrauer H, Lindemann A, Hauser F et al. Genome-wide transcript analysis of Bradyrhizobium japonicum bacteroids in soybean root nodules. Mol Plant Microbe Interact 2007;20:1353–1363 [CrossRef][PubMed]
    [Google Scholar]
  16. Chang WS, Franck WL, Cytryn E, Jeong S, Joshi T et al. An oligonucleotide microarray resource for transcriptional profiling of Bradyrhizobium japonicum. Mol Plant Microbe Interact 2007;20:1298–1307 [CrossRef][PubMed]
    [Google Scholar]
  17. Tsukada S, Aono T, Akiba N, Lee KB, Liu CT et al. Comparative genome-wide transcriptional profiling of Azorhizobium caulinodans ORS571 grown under free-living and symbiotic conditions. Appl Environ Microbiol 2009;75:5037–5046 [CrossRef][PubMed]
    [Google Scholar]
  18. Li Y, Tian CF, Chen WF, Wang L, Sui XH et al. High-resolution transcriptomic analyses of Sinorhizobium sp. NGR234 bacteroids in determinate nodules of Vigna unguiculata and indeterminate nodules of Leucaena leucocephala. PLoS One 2013;8:e70531 [CrossRef][PubMed]
    [Google Scholar]
  19. Barnett MJ, Toman CJ, Fisher RF, Long SR. A dual-genome symbiosis chip for coordinate study of signal exchange and development in a prokaryote-host interaction. Proc Natl Acad Sci USA 2004;101:16636–16641 [CrossRef][PubMed]
    [Google Scholar]
  20. Domínguez-Ferreras A, Pérez-Arnedo R, Becker A, Olivares J, Soto MJ et al. Transcriptome profiling reveals the importance of plasmid pSymB for osmoadaptation of Sinorhizobium meliloti. J Bacteriol 2006;188:7617–7625 [CrossRef][PubMed]
    [Google Scholar]
  21. Prell J, Bourdès A, Kumar S, Lodwig E, Hosie A et al. Role of symbiotic auxotrophy in the Rhizobium-legume symbioses. PLoS One 2010;5:e13933 [CrossRef][PubMed]
    [Google Scholar]
  22. Jiménez-Guerrero I, Acosta-Jurado S, del Cerro P, Navarro-Gómez P, López-Baena FJ et al. Transcriptomic studies of the effect of nod Gene-inducing molecules in rhizobia: different weapons, one purpose. Genes 2018;9:1–27 [CrossRef][PubMed]
    [Google Scholar]
  23. Roux B, Rodde N, Jardinaud MF, Timmers T, Sauviac L et al. An integrated analysis of plant and bacterial gene expression in symbiotic root nodules using laser-capture microdissection coupled to RNA sequencing. Plant J 2014;77:817–837 [CrossRef][PubMed]
    [Google Scholar]
  24. Lamb JW, Hombrecher G, Johnston AWB. Plasmid-determined nodulation and nitrogen-fixation abilities in Rhizobium phaseoli. Mol Gen Genet 1982;186:449–452 [CrossRef]
    [Google Scholar]
  25. Downie JA, Hombrecher G, Ma Q-S, Knight CD, Wells B et al. Cloned nodulation genes of Rhizobium leguminosarum determine host-range specificity. Mol Gen Genet 1983;190:359–365 [CrossRef]
    [Google Scholar]
  26. Beringer JE. R factor transfer in Rhizobium leguminosarum. J Gen Microbiol 1974;84:188–198 [CrossRef][PubMed]
    [Google Scholar]
  27. Poole PS, Blyth A, Reid CJ, Walters K. myo-Inositol catabolism and catabolite regulation in Rhizobium leguminosarum bv. viciae. Microbiology 1994;140:2787–2795 [CrossRef]
    [Google Scholar]
  28. Walshaw DL, Wilkinson A, Mundy M, Smith M, Poole PS. Regulation of the TCA cycle and the general amino acid permease by overflow metabolism in Rhizobium leguminosarum. Microbiology 1997;143:2209–2221 [CrossRef][PubMed]
    [Google Scholar]
  29. Langmead B, Salzberg SL. Fast gapped-read alignment with Bowtie 2. Nat Methods 2012;9:357–359 [CrossRef][PubMed]
    [Google Scholar]
  30. Li H, Handsaker B, Wysoker A, Fennell T, Ruan J et al. The Sequence Alignment/Map format and SAMtools. Bioinformatics 2009;25:2078–2079 [CrossRef][PubMed]
    [Google Scholar]
  31. Wagner GP, Kin K, Lynch VJ. Measurement of mRNA abundance using RNA-seq data: RPKM measure is inconsistent among samples. Theory Biosci 2012;131:281–285 [CrossRef][PubMed]
    [Google Scholar]
  32. Anders S, Huber W. Differential expression analysis for sequence count data. Genome Biol 2010;11:R106 [CrossRef][PubMed]
    [Google Scholar]
  33. Markowitz VM, Chen IM, Palaniappan K, Chu K, Szeto E et al. IMG 4 version of the integrated microbial genomes comparative analysis system. Nucleic Acids Res 2014;42:D560–D567 [CrossRef][PubMed]
    [Google Scholar]
  34. Edgar RC. Search and clustering orders of magnitude faster than BLAST. Bioinformatics 2010;26:2460–2461 [CrossRef][PubMed]
    [Google Scholar]
  35. Conant GC, Wolfe KH. GenomeVx: simple web-based creation of editable circular chromosome maps. Bioinformatics 2008;24:861–862 [CrossRef][PubMed]
    [Google Scholar]
  36. Lodwig EM, Hosie AH, Bourdès A, Findlay K, Allaway D et al. Amino-acid cycling drives nitrogen fixation in the legume-Rhizobium symbiosis. Nature 2003;422:722–726 [CrossRef][PubMed]
    [Google Scholar]
  37. Lodwig EM, Leonard M, Marroqui S, Wheeler TR, Findlay K et al. Role of polyhydroxybutyrate and glycogen as carbon storage compounds in pea and bean bacteroids. Mol Plant Microbe Interact 2005;18:67–74 [CrossRef][PubMed]
    [Google Scholar]
  38. González V, Santamaría RI, Bustos P, Hernández-González I, Medrano-Soto A et al. The partitioned Rhizobium etli genome: genetic and metabolic redundancy in seven interacting replicons. Proc Natl Acad Sci USA 2006;103:3834–3839 [CrossRef][PubMed]
    [Google Scholar]
  39. Young JP, Crossman LC, Johnston AW, Thomson NR, Ghazoui ZF et al. The genome of Rhizobium leguminosarum has recognizable core and accessory components. Genome Biol 2006;7:R34 [CrossRef][PubMed]
    [Google Scholar]
  40. Carver TJ, Rutherford KM, Berriman M, Rajandream MA, Barrell BG et al. ACT: the Artemis comparison tool. Bioinformatics 2005;21:3422–3423 [CrossRef][PubMed]
    [Google Scholar]
  41. Thompson JM, Jones HA, Perry RD. Molecular characterization of the hemin uptake locus (hmu) from Yersinia pestis and analysis of hmu mutants for hemin and hemoprotein utilization. Infect Immun 1999;67:3879–3892[PubMed]
    [Google Scholar]
  42. Todd JD, Wexler M, Sawers G, Yeoman KH, Poole PS et al. RirA, an iron-responsive regulator in the symbiotic bacterium Rhizobium leguminosarum. Microbiology 2002;148:4059–4071 [CrossRef][PubMed]
    [Google Scholar]
  43. Economou A, Hamilton WD, Johnston AW, Downie JA. The Rhizobium nodulation gene nodO encodes a Ca2(+)-binding protein that is exported without N-terminal cleavage and is homologous to haemolysin and related proteins. Embo J 1990;9:349–354 [CrossRef][PubMed]
    [Google Scholar]
  44. Poupot R, Martinez-Romero E, Gautier N, Promé JC. Wild type Rhizobium etli, a bean symbiont, produces acetyl-fucosylated, N-methylated, and carbamoylated nodulation factors. J Biol Chem 1995;270:6050–6055 [CrossRef][PubMed]
    [Google Scholar]
  45. Kelly S, Sullivan JT, Kawaharada Y, Radutoiu S, Ronson CW et al. Regulation of Nod factor biosynthesis by alternative NodD proteins at distinct stages of symbiosis provides additional compatibility scrutiny. Environ Microbiol 2018;20:97–110 [CrossRef][PubMed]
    [Google Scholar]
  46. Ramachandran VK, East AK, Karunakaran R, Downie JA, Poole PS. Adaptation of Rhizobium leguminosarum to pea, alfalfa and sugar beet rhizospheres investigated by comparative transcriptomics. Genome Biol 2011;12:R106 [CrossRef][PubMed]
    [Google Scholar]
  47. Marie C. Abnormal bacteroid development in nodules induced by a glucosamine synthase mutant of Rhizobium ieguminosarum. Mol Plant Microbe Interact 1994;7:482–487 [CrossRef]
    [Google Scholar]
  48. Danino VE, Wilkinson A, Edwards A, Downie JA. Recipient-induced transfer of the symbiotic plasmid pRL1JI in Rhizobium leguminosarum bv. viciae is regulated by a quorum-sensing relay. Mol Microbiol 2003;50:511–525 [CrossRef][PubMed]
    [Google Scholar]
  49. Kullik I, Fritsche S, Knobel H, Sanjuan J, Hennecke H et al. Bradyrhizobium japonicum has two differentially regulated, functional homologs of the sigma 54 gene (rpoN). J Bacteriol 1991;173:1125–1138 [CrossRef][PubMed]
    [Google Scholar]
  50. Michiels J, Xi C, Verhaert J, Vanderleyden J. The functions of Ca(2+) in bacteria: a role for EF-hand proteins?. Trends Microbiol 2002;10:87–93 [CrossRef][PubMed]
    [Google Scholar]
  51. Pötter M, Steinbüchel A. Poly(3-hydroxybutyrate) granule-associated proteins: impacts on poly(3-hydroxybutyrate) synthesis and degradation. Biomacromolecules 2005;6:552–560 [CrossRef][PubMed]
    [Google Scholar]
  52. Hawkins FK, Johnston AW. Transcription of a Rhizobium leguminosarum biovar phaseoli gene needed for melanin synthesis is activated by nifA of Rhizobium and Klebsiella pneumoniae. Mol Microbiol 1988;2:331–337 [CrossRef][PubMed]
    [Google Scholar]
  53. Hawkins FKL, Kennedy C, Johnston AWB. A Rhizobium leguminosarum gene required for symbiotic nitrogen fixation, melanin synthesis and normal growth on certain growth media. J Gen Microbiol 1991;137:1721–1728 [CrossRef]
    [Google Scholar]
  54. Domínguez DC, Guragain M, Patrauchan M. Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2015;57:151–165 [CrossRef][PubMed]
    [Google Scholar]
  55. Xi C, Schoeters E, Vanderleyden J, Michiels J. Symbiosis-specific expression of Rhizobium etli casA encoding a secreted calmodulin-related protein. Proc Natl Acad Sci USA 2000;97:11114–11119 [CrossRef][PubMed]
    [Google Scholar]
  56. Wippel K, Long SR. Contributions of Sinorhizobium meliloti transcriptional regulator DksA to bacterial growth and efficient symbiosis with Medicago sativa. J Bacteriol 2016;198:1374–1383 [CrossRef][PubMed]
    [Google Scholar]
  57. Prell J, White JP, Bourdes A, Bunnewell S, Bongaerts RJ et al. Legumes regulate Rhizobium bacteroid development and persistence by the supply of branched-chain amino acids. Proc Natl Acad Sci USA 2009;106:12477–12482 [CrossRef][PubMed]
    [Google Scholar]
  58. Hosie AH, Allaway D, Galloway CS, Dunsby HA, Poole PS. Rhizobium leguminosarum has a second general amino acid permease with unusually broad substrate specificity and high similarity to branched-chain amino acid transporters (Bra/LIV) of the ABC family. J Bacteriol 2002;184:4071–4080 [CrossRef][PubMed]
    [Google Scholar]
  59. Walshaw DL, Poole PS. The general L-amino acid permease of Rhizobium leguminosarum is an ABC uptake system that also influences efflux of solutes. Mol Microbiol 1996;21:1239–1252 [CrossRef][PubMed]
    [Google Scholar]
  60. Hosie AH, Allaway D, Jones MA, Walshaw DL, Johnston AW et al. Solute-binding protein-dependent ABC transporters are responsible for solute efflux in addition to solute uptake. Mol Microbiol 2001;40:1449–1459 [CrossRef][PubMed]
    [Google Scholar]
  61. Walshaw DL, Lowthorpe S, East A, Poole PS. Distribution of a sub-class of bacterial ABC polar amino acid transporter and identification of an N-terminal region involved in solute specificity. FEBS Lett 1997;414:397–401[PubMed]
    [Google Scholar]
  62. Lodwig E, Poole P. Metabolism of Rhizobium bacteroids. CRC Crit Rev Plant Sci 2003;22:37–78 [CrossRef]
    [Google Scholar]
  63. Prell J, Bourdès A, Karunakaran R, Lopez-Gomez M, Poole P. Pathway of gamma-aminobutyrate metabolism in Rhizobium leguminosarum 3841 and its role in symbiosis. J Bacteriol 2009;191:2177–2186 [CrossRef][PubMed]
    [Google Scholar]
  64. Fox MA, Karunakaran R, Leonard ME, Mouhsine B, Williams A et al. Characterization of the quaternary amine transporters of Rhizobium leguminosarum bv. viciae 3841. FEMS Microbiol Lett 2008;287:212–220 [CrossRef][PubMed]
    [Google Scholar]
  65. Mauchline TH, Fowler JE, East AK, Sartor AL, Zaheer R et al. Mapping the Sinorhizobium meliloti 1021 solute-binding protein-dependent transportome. Proc Natl Acad Sci USA 2006;103:17933–17938 [CrossRef][PubMed]
    [Google Scholar]
  66. Meloni S, Rey L, Sidler S, Imperial J, Ruiz-Argüeso T et al. The twin-arginine translocation (Tat) system is essential for Rhizobium-legume symbiosis. Mol Microbiol 2003;48:1195–1207 [CrossRef][PubMed]
    [Google Scholar]
  67. Krehenbrink M, Downie JA. Identification of protein secretion systems and novel secreted proteins in Rhizobium leguminosarum bv. viciae. BMC Genomics 2008;9:55 [CrossRef][PubMed]
    [Google Scholar]
  68. Zavaleta-Pastor M, Sohlenkamp C, Gao JL, Guan Z, Zaheer R et al. Sinorhizobium meliloti phospholipase C required for lipid remodeling during phosphorus limitation. Proc Natl Acad Sci USA 2010;107:302–307 [CrossRef][PubMed]
    [Google Scholar]
  69. Carter RA, Yeoman KH, Klein A, Hosie AH, Sawers G et al. dpp genes of Rhizobium leguminosarum specify uptake of delta-aminolevulinic acid. Mol Plant Microbe Interact 2002;15:69–74 [CrossRef][PubMed]
    [Google Scholar]
  70. Létoffé S, Delepelaire P, Wandersman C. The housekeeping dipeptide permease is the Escherichia coli heme transporter and functions with two optional peptide binding proteins. Proc Natl Acad Sci USA 2006;103:12891–12896 [CrossRef][PubMed]
    [Google Scholar]
  71. Tett AJ, Rudder SJ, Bourdès A, Karunakaran R, Poole PS. Regulatable vectors for environmental gene expression in Alphaproteobacteria. Appl Environ Microbiol 2012;78:7137–7140 [CrossRef][PubMed]
    [Google Scholar]
  72. Preisig O, Anthamatten D, Hennecke H. Genes for a microaerobically induced oxidase complex in Bradyrhizobium japonicum are essential for a nitrogen-fixing endosymbiosis. Proc Natl Acad Sci USA 1993;90:3309–3313 [CrossRef][PubMed]
    [Google Scholar]
  73. Nikaido H. Molecular basis of bacterial outer membrane permeability revisited. Microbiol Mol Biol Rev 2003;67:593–656 [CrossRef][PubMed]
    [Google Scholar]
  74. Babinski KJ, Ribeiro AA, Raetz CR. The Escherichia coli gene encoding the UDP-2,3-diacylglucosamine pyrophosphatase of lipid A biosynthesis. J Biol Chem 2002;277:25937–25946 [CrossRef][PubMed]
    [Google Scholar]
  75. Henderson B, Allan E, Coates AR. Stress wars: the direct role of host and bacterial molecular chaperones in bacterial infection. Infect Immun 2006;74:3693–3706 [CrossRef][PubMed]
    [Google Scholar]
  76. Crook MB, Draper AL, Guillory RJ, Griffitts JS. The Sinorhizobium meliloti essential porin RopA1 is a target for numerous bacteriophages. J Bacteriol 2013;195:3663–3671 [CrossRef][PubMed]
    [Google Scholar]
  77. Murray JD, Liu CW, Chen Y, Miller AJ. Nitrogen sensing in legumes. J Exp Bot 2017;68:1919–1926 [CrossRef][PubMed]
    [Google Scholar]
  78. Cheng G, Karunakaran R, East AK, Poole PS. Mulitiplicity of sulfate and molybdate transporters and their role in nitrogen fixation in Rhizobium leguminosarum bv. viciae Rlv3841. Mol Plant Microbe Interact 2016;29:143–152 [CrossRef]
    [Google Scholar]
  79. Thöny-Meyer L, Künzler P. The Bradyrhizobium japonicum aconitase gene (acnA) is important for free-living growth but not for an effective root nodule symbiosis. J Bacteriol 1996;178:6166–6172 [CrossRef][PubMed]
    [Google Scholar]
  80. Green LS, Emerich DW. The formation of nitrogen-fixing bacteroids is delayed but not abolished in soybean infected by an [alpha]-ketoglutarate dehydrogenase-deficient mutant of Bradyrhizobium japonicum. Plant Physiol 1997;114:1359–1368 [CrossRef][PubMed]
    [Google Scholar]
  81. Prell J, Boesten B, Poole P, Priefer UB. The Rhizobium leguminosarum bv. viciae VF39 gamma-aminobutyrate (GABA) aminotransferase gene (gabT) is induced by GABA and highly expressed in bacteroids. Microbiology 2002;148:615–623 [CrossRef][PubMed]
    [Google Scholar]
  82. Kolberg M, Strand KR, Graff P, Andersson KK. Structure, function, and mechanism of ribonucleotide reductases. Biochim Biophys Acta 2004;1699:1–34 [CrossRef][PubMed]
    [Google Scholar]
  83. Finnie C, Zorreguieta A, Hartley NM, Downie JA. Characterization of Rhizobium leguminosarum exopolysaccharide glycanases that are secreted via a type I exporter and have a novel heptapeptide repeat motif. J Bacteriol 1998;180:1691–1699[PubMed]
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/mgen/10.1099/mgen.0.000254
Loading
/content/journal/mgen/10.1099/mgen.0.000254
Loading

Data & Media loading...

Supplements

Supplementary File 1

PDF

Supplementary File 2

Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error