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The Role of Trehalose Metabolism in Chloroplast Development and Leaf Senescence

  • Astrid WinglerEmail author
  • Matthew Paul
Chapter
Part of the Advances in Photosynthesis and Respiration book series (AIPH, volume 36)

Summary

Trehalose (α-D-glucopyranosyl-(1,1)-α-D-glucopyranoside) is a non-reducing disaccharide that acts as a storage carbohydrate, transport sugar and stress protectant in microorganisms and invertebrate animals. In plants, trehalose synthesis is catalyzed by trehalose 6-phosphate synthase (TPS) followed by trehalose 6-phosphate phosphatase (TPP). Despite activity of this biosynthetic pathway, trehalose does not usually accumulate to large amounts in plant tissues. The low content of trehalose indicates that the conventional role as carbon source or compatible solute is unlikely in plants. Instead, sucrose has assumed this role, while trehalose metabolism mainly appears to fulfill a signaling function. Work with transgenic plants has revealed a role of trehalose 6-phosphate (T6P), the precursor of trehalose in the biosynthetic pathway, as signal for high availability of carbon, in particular in the form of sucrose. While T6P is likely to be synthesized in the cytosol, it stimulates starch synthesis in the chloroplasts. In seedlings, T6P activates pathways for the synthesis of amino acids, proteins and nucleotides, but also represses photosynthesis genes. These changes in gene expression can be explained by inhibition of the activity of sucrose non-fermenting-1-related protein kinase 1 (SnRK1) by T6P in growing tissues. Since SnRK1 serves as an integrator of transcriptional networks in starvation signaling, the inhibitory effect of T6P is consistent with its role as a high carbon signal. High T6P also improves sucrose utilization and growth of seedlings. In mature leaves, however, T6P does not inhibit SnRK1. Although photosynthesis on a leaf area basis is enhanced in response to high T6P content, altered leaf shape restricts overall plant carbon gain and growth. Transgenic plants expressing genes for trehalose synthesis generally show improved photosynthetic function during stress. More recently, enhanced stress tolerance, while avoiding negative effects of T6P on leaf development, has been achieved by expressing TPS/TPP fusion constructs or by targeting trehalose synthesis to the chloroplast. This suggests a protective role of T6P and/or trehalose in the chloroplast, although trehalose content was probably too low to act as a compatible solute. Trehalose metabolism also affects reproductive plant development, including a role of T6P in floral initiation as well as in the regulation of leaf senescence. Development of photosynthesis is therefore regulated by trehalose metabolism in many different ways, with T6P typically acting as a signal for high carbon availability.

Keywords

Leaf Senescence Floral Initiation Starch Synthesis Resurrection Plant Photosynthetic Function 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations:

Φ PSII

PSII operating efficiency;

AGPase

ADP-glucose pyrophosphorylase;

G6P

Glucose 6-phosphate;

SnRK1

Sucrose non-fermenting-1-related protein kinase 1;

T6P

Trehalose 6-phosphate;

TPP

Trehalose 6-phosphate phosphatase;

TPS

Trehalose 6-phosphate synthase

Notes

Acknowledgments

Our work was supported by the Biotechnology and Biological Sciences Research Council, United Kingdom (grants BB/C51257X/1, BB/D006112/1 and BB/C512645/1). Rothamsted Research receives grant-aided support from the Biotechnological and Biological Sciences Research Council.

References

  1. Adams RP, Kendall E, Kartha KK (1990) Comparison of free sugars in growing and desiccated plants of Selaginella lepidophylla. Biochem Syst Ecol 18:107–110CrossRefGoogle Scholar
  2. Avonce N, Leyman B, Mascorro-Gallardo JO, Van Dijck P, Thevelein JM, Iturriaga G (2004) The Arabidopsis trehalose 6-phosphate synthase AtTPS1 gene is a regulator of glucose, abscisic acid and stress signalling. Plant Physiol 136:3649–3659PubMedCrossRefGoogle Scholar
  3. Bae H, Herman E, Bailey B, Bae HJ, Sicher R (2005) Exogenous trehalose alters Arabidopsis transcripts involved in cell wall modification, abiotic stress, nitrogen metabolism, and plant defense. Physiol Plant 125:114–126CrossRefGoogle Scholar
  4. Baena-González E, Sheen J (2008) Convergent energy and stress signaling. Trends Plant Sci 13:474–482PubMedCrossRefGoogle Scholar
  5. Baena-González E, Rolland F, Thevelein JM, Sheen J (2007) A central integrator of transcription networks in plant stress and energy signalling. Nature 448:938–942PubMedCrossRefGoogle Scholar
  6. Blázquez MA, Santos E, Flores CL, Martínez-Zapater JM, Salinas J, Gancedo C (1998) Isolation and molecular characterization of the Arabidopsis TPS1 gene, encoding trehalose-6-phosphate synthase. Plant J 13:685–689PubMedCrossRefGoogle Scholar
  7. Boonman A, Anten NPR, Dueck TA, Jordi WJRM, van der Werf A, Voesenek LACJ, Pons TL (2006) Functional significance of shade-induced leaf senescence in dense canopies: an experimental test using transgenic tobacco. Am Nat 168:597–607PubMedCrossRefGoogle Scholar
  8. Brodmann D, Schuller A, Ludwig-Müller J, Aeschbacher RA, Wiemken A, Boller T, Wingler A (2002) Induction of trehalase in Arabidopsis plants infected with the trehalose-producing ­pathogen Plasmodiophora brassicae. Mol Plant Microbe Interact 15:693–700Google Scholar
  9. Buchanan BB, Balmer Y (2005) Redox regulation: a broadening horizon. Annu Rev Plant Biol 56:187–220PubMedCrossRefGoogle Scholar
  10. Corbesier L, Coupland G (2006) The quest for florigen: a review of recent progress. J Exp Bot 57:3395–3403PubMedCrossRefGoogle Scholar
  11. Crowe JH, Carpenter JF, Crowe LM (1998) The role of vitrification in anhydrobiosis. Annu Rev Physiol 60:73–103PubMedCrossRefGoogle Scholar
  12. Drennan PM, Smith MT, Goldsworthy D, van Staden J (1993) The occurrence of trehalose in the leaves of the desiccation-tolerant angiosperm Myrothamnus flabellifolius Welw. J Plant Physiol 142:493–496CrossRefGoogle Scholar
  13. Eastmond PJ, van Dijken AJ, Spielman M, Kerr A, Tissier AF, Dickinson HG, Jones JD, Smeekens SC, Graham IA (2002) Trehalose-6-phosphate synthase 1, which catalyses the first step in trehalose synthesis, is essential for Arabidopsis embryo maturation. Plant J 29:225–235PubMedCrossRefGoogle Scholar
  14. Emanuelsson O, Brunak S, von Heijne G, Nielsen H (2007) Locating proteins in the cell using TargetP, SignalP and related tools. Nat Protoc 2:953–971PubMedCrossRefGoogle Scholar
  15. Fernandez O, Béthencourt L, Quero A, Sangwan RS, Clément C (2010) Trehalose and plant stress responses: friend or foe? Trends Plant Sci 15:409–417PubMedCrossRefGoogle Scholar
  16. Fragoso S, Espíndola L, Páez-Valencia J, Gamboa A, Camacho Y, Martínez-Barajas E, Coello P (2009) SnRK1 isoforms AKIN10 and AKIN11 are differentially regulated in Arabidopsis plants under phosphate starvation. Plant Physiol 149:1906–1916PubMedCrossRefGoogle Scholar
  17. Frison M, Parrou JL, Guillaumot D, Masquelier D, Francois J, Chaumont F, Batoko H (2007) The Arabidopsis thaliana trehalase is a plasma membrane-bound enzyme with extracellular activity. FEBS Lett 581:4010–4016PubMedCrossRefGoogle Scholar
  18. Garg AK, Kim JK, Owens TG, Ranwala AP, Choi YD, Kochian LV, Wu RJ (2002) Trehalose accumulation in rice plants confers high tolerance levels to different abiotic stresses. Proc Natl Acad Sci USA 99:15898–15903PubMedCrossRefGoogle Scholar
  19. Ge LF, Chao DY, Shi M, Zhu MZ, Gao JP, Lin HX (2008) Overexpression of the trehalose-6-phosphate phosphatase gene OsTPP1 confers stress tolerance in rice and results in the activation of stress responsive genes. Planta 228:191–201PubMedCrossRefGoogle Scholar
  20. Geelen D, Royackers K, Vanstraelen M, De Bus M, Inze D, Van Dijck P, Thevelein JM, Leyman B (2007) Trehalose 6-P synthase. AtTPS1 high molecular weight complexes in yeast and Arabidopsis. Plant Sci 173:426–437CrossRefGoogle Scholar
  21. Gerhardt R, Stitt M, Heldt HW (1987) Subcellular metabolite levels in spinach leaves: regulation of sucrose synthesis during alteration of photosynthetic partitioning. Plant Physiol 83:399–407PubMedCrossRefGoogle Scholar
  22. Gerrits N, Turk SC, van Dun KP, Hulleman SH, Visser RG, Weisbeek PJ, Smeekens SC (2001) Sucrose metabolism in plastids. Plant Physiol 125:926–934PubMedCrossRefGoogle Scholar
  23. Gissot L, Polge C, Jossier M, Girin T, Bouly JP, Kreis M, Thomas M (2006) AKINβγ contributes to SnRK1 heterotrimeric complexes and interacts with two proteins implicated in plant pathogen resistance through its KIS/GBD sequence. Plant Physiol 142:931–944PubMedCrossRefGoogle Scholar
  24. Glassop D, Roessner U, Bacic A, Bonnett GD (2007) Changes in the sugarcane metabolome with stem development. Are they related to sucrose accumulation? Plant Cell Physiol 48:573–584PubMedCrossRefGoogle Scholar
  25. Goddijn O, Smeekens S (1998) Sensing trehalose synthesis in plants. Plant J 14:143–146PubMedCrossRefGoogle Scholar
  26. Goddijn OJ, Verwoerd TC, Voogd E, Krutwagen RW, de Graaf PT, van Dun K, Poels J, Ponstein AS, Damm B, Pen J (1997) Inhibition of trehalase activity enhances trehalose accumulation in transgenic plants. Plant Physiol 113:181–190PubMedCrossRefGoogle Scholar
  27. Gómez LD, Gilday A, Feil R, Lunn JE, Graham IA (2010) AtTPS1-mediated trehalose 6-phosphate synthesis is essential for embryogenic and vegetative growth and responsiveness to ABA in germinating seeds and stomatal guard cells. Plant J 64:1–13PubMedGoogle Scholar
  28. Harthill JE, Meek SEM, Morrice N, Peggie MW, Borch J, Wong BHC, MacKintosh C (2006) Phosphorylation and 14-3-3 binding of Arabidopsis trehalose-phosphate synthase 5 in response to 2-deoxyglucose. Plant J 47:211–223PubMedCrossRefGoogle Scholar
  29. Holström KO, Mäntylä E, Welin B, Mandal A, Pavla ET (1996) Drought tolerance in tobacco. Nature 379:683–684CrossRefGoogle Scholar
  30. Hummel I, Pantin F, Sulpice R, Piques M, Rolland G, Dauzat M, Christophe A, Pervent M, Bouteillé M, Stitt M, Gibon Y, Muller B (2010) Arabidopsis plants acclimate to water deficit at low cost through changes of carbon usage: an integrated perspective using growth, metabolite, enzyme, and gene expression analysis. Plant Physiol 154:357–372PubMedCrossRefGoogle Scholar
  31. Iordachescu M, Imai R (2008) Trehalose biosynthesis in response to abiotic stresses. J Integr Plant Biol 50:1223–1229PubMedCrossRefGoogle Scholar
  32. Jang IC, Oh SJ, Seo JS, Choi WB, Song SI, Kim CH, Kim YS, Seo HS, Choi YD, Nahm BH, Kim JK (2003) Expression of a bifunctional fusion of the Escherichia coli genes for trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase in transgenic rice plants increases trehalose accumulation and abiotic stress tolerance without stunting growth. Plant Physiol 131:516–524PubMedCrossRefGoogle Scholar
  33. Karim S, Aronsson H, Ericson H, Pirhonen M, Leyman B, Welin B, Mäntylä E, Palva ET, Van Dijck P, Holström K-O (2007) Improved drought tolerance without undesired side effects in transgenic plants producing trehalose. Plant Mol Biol 64:371–386PubMedCrossRefGoogle Scholar
  34. Kolbe A, Tiessen A, Schluepmann H, Paul M, Ulrich S, Geigenberger P (2005) Trehalose 6-phosphate regulates starch synthesis via post-translational redox activation of ADP-glucose pyrophosphorylase. Proc Natl Acad Sci USA 102:11118–11123PubMedCrossRefGoogle Scholar
  35. Kühn C (2003) A comparison of the sucrose transporter systems of different plant species. Plant Biol 5:215–232CrossRefGoogle Scholar
  36. Lee SB, Kwon HB, Kwon SJ, Park SC, Jeong MJ, Han SE, Byun MO, Daniell H (2003) Accumulation of trehalose within transgenic chloroplasts confers drought tolerance. Mol Breed 11:1–13CrossRefGoogle Scholar
  37. Leonhardt N, Kwak JM, Robert N, Waner D, Leonhardt G, Schroeder JI (2004) Microarray expression analyses of Arabidopsis guard cells and isolation of a recessive abscisic acid hypersensitive protein phosphatase 2C mutant. Plant Cell 16:596–615PubMedCrossRefGoogle Scholar
  38. Li P, Ma S, Bohnert HJ (2008) Coexpression characteristics of trehalose-6-phosphate phosphatase subfamily genes reveal different functions in a network context. Physiol Plant 133:544–556PubMedCrossRefGoogle Scholar
  39. Lunn JE (2007) Gene families and evolution of trehalose metabolism in plants. Funct Plant Biol 34:550–563CrossRefGoogle Scholar
  40. Lunn JE, Feil R, Hendriks JHM, Gibon Y, Morcuende R, Osuna D, Scheible W-R, Carillo P, Hajirezaei M-R, Stitt M (2006) Sugar-induced increases in trehalose 6-phosphate are correlated with redox activation of ADP-glucose pyrophosphorylase and higher rates of starch synthesis in Arabidopsis thaliana. Biochem J 397:139–148PubMedCrossRefGoogle Scholar
  41. McBride A, Ghilagaber S, Nikolaev A, Hardie DG (2009) The glycogen binding domain on the AMPK beta subunit allows the kinase to act as a glycogen sensor. Cell Metab 9:7–8CrossRefGoogle Scholar
  42. Miranda JA, Avonce N, Suárez R, Thevelein JM, Van Dijck P, Iturriaga G (2007) A bifunctional TPS-TPP enzyme from yeast confers tolerance to multiple and extreme abiotic-stress conditions in transgenic Arabidopsis. Planta 226:1411–1421PubMedCrossRefGoogle Scholar
  43. Moore B, Zhou L, Rolland F, Hall Q, Cheng WH, Liu YX, Hwang I, Jones T, Sheen J (2003) Role of the Arabidopsis glucose sensor HXK1 in nutrient, light, and hormonal signaling. Science 300:332–336PubMedCrossRefGoogle Scholar
  44. Müller J, Aeschbacher RA, Wingler A, Boller T, Wiemken A (2001) Trehalose and trehalase in Arabidopsis. Plant Physiol 125:1086–1093PubMedCrossRefGoogle Scholar
  45. Noodén LD, Guiamét JJ (1989) Regulation of assimilation and senescence by the fruit in monocarpic plants. Physiol Plant 77:267–274CrossRefGoogle Scholar
  46. Noodén LD, Penney JP (2001) Correlative controls of senescence and plant death in Arabidopsis thaliana. J Exp Bot 52:2151–2159PubMedGoogle Scholar
  47. Paul MJ, Primavesi LF, Jhurreea D, Zhang Y (2008) Trehalose metabolism and signalling. Annu Rev Plant Biol 59:417–441PubMedCrossRefGoogle Scholar
  48. Paul MJ, Jhurreea D, Zhang Y, Primavesi LF, Delatte T, Schluepmann H, Wingler A (2010) Up-regulation of biosynthetic processes associated with growth by trehalose 6-phosphate. Plant Signal Behav 5:386–392PubMedCrossRefGoogle Scholar
  49. Pellny TK, Ghannoum O, Conroy JP, Schluepmann H, Smeekens S, Andralojc J, Krause KP, Goddijn O, Paul MJ (2004) Genetic modification of photosynthesis with E. coli genes for trehalose synthesis. Plant Biotech J 2:71–82CrossRefGoogle Scholar
  50. Pilon-Smits EAH, Terry N, Sears T, Kim H, Zayed A, Hwang S, Van Dun K, Voogd E, Verwoerd TC, Krutwagen RWHH, Goddijn OJM (1998) Trehalose-producing transgenic tobacco plants show improved growth performance under drought stress. J Plant Physiol 152:525–532CrossRefGoogle Scholar
  51. Polge C, Thomas M (2007) SNF1/AMPK/SnRK1 kinases, global regulators at the heart of energy control. Trends Plant Sci 12:1360–1385CrossRefGoogle Scholar
  52. Pourtau N, Jennings R, Pelzer E, Pallas J, Wingler A (2006) Effect of sugar-induced senescence on gene expression and implications for the regulation of senescence in Arabidopsis. Planta 224:556–568PubMedCrossRefGoogle Scholar
  53. Ramon M, de Smet I, Vandesteene L, Naudts M, Leyman B, van Dijck P, Rolland F, Beeckman T, Thevelein JM (2009) Extensive expression regulation and lack of heterologous enzymatic activity of the Class II trehalose metabolism proteins from Arabidopsis thaliana. Plant Cell Environ 32:1015–1032PubMedCrossRefGoogle Scholar
  54. Roessner U, Wagner C, Kopka J, Trethewey RN, Willmitzer L (2000) Simultaneous analysis of metabolites in potato tuber by gas chromatography–mass spectrometry. Plant J 23:131–142PubMedCrossRefGoogle Scholar
  55. Roldán M, Gómez-Mena C, Ruiz-García L, Salinas J, Martínez-Zapater JM (1999) Sucrose availability on the aerial part of the plant promotes morphogenesis and flowering of Arabidopsis in the dark. Plant J 20:581–591PubMedCrossRefGoogle Scholar
  56. Romero C, Bellés JM, Vayá JL, Serrano R, Culiáñez-Macia FA (1997) Expression of the yeast trehalose-6-phosphate synthase gene in transgenic tobacco plants: pleiotropic phenotypes include drought tolerance. Planta 201:293–297PubMedCrossRefGoogle Scholar
  57. Sadras VO, Echarte L, Andrade FH (2000) Profiles of leaf senescence during reproductive growth of sunflower and maize. Ann Bot 85:187–195CrossRefGoogle Scholar
  58. Satoh-Nagasawa N, Nagasawa N, Malcomber S, Sakai H, Jackson D (2006) A trehalose metabolic enzyme controls inflorescence architecture in maize. Nature 441:227–230PubMedCrossRefGoogle Scholar
  59. Schluepmann H, Pellny T, van Dijken A, Smeekens S, Paul M (2003) Trehalose 6-phosphate is indispensable for carbohydrate utilization and growth in Arabidopsis thaliana. Proc Natl Acad Sci USA 100:6849–6854PubMedCrossRefGoogle Scholar
  60. Schmid M, Davison TS, Henz SR, Pape UJ, Demar M, Vingron M, Schölkopf B, Weigel D, Lohmann J (2005) A gene expression map of Arabidopsis thaliana development. Nature Genet 37:501–506PubMedCrossRefGoogle Scholar
  61. Shi MZ, Xie DY (2010) Features of anthocyanin biosynthesis in pap1-D and wild-type Arabidopsis thaliana plants grown in different light intensity and culture media conditions. Planta 231:1385–1400PubMedCrossRefGoogle Scholar
  62. Smith AM, Stitt M (2007) Coordination of carbon supply and plant growth. Plant Cell Environ 30:1126–1149PubMedCrossRefGoogle Scholar
  63. Sulpice R, Pyl ET, Ishihara H, Trenkamp S, Steinfath M, Witucka-Wall H, Gibon Y, Usadel B, Poree F, Piques MC, Von Korff M, Steinhauser MC, Keurentjes JJ, Guenther M, Hoehne M, Selbig J, Fernie AR, Altmann T, Stitt M (2009) Starch as a major integrator in the regulation of plant growth. Proc Natl Acad Sci USA 106:10348–10353PubMedCrossRefGoogle Scholar
  64. Teng S, Keurentjes J, Bentsink L, Koornneef M, Smeekens S (2005) Sucrose-specific induction of anthocyanin biosynthesis in Arabidopsis requires the MYB75/PAP1 gene. Plant Physiol 139:1840–1852PubMedCrossRefGoogle Scholar
  65. Tiessen A, Prescha K, Branscheid A, Palacios N, McKibbin R, Halford NG, Geigenberger P (2003) Evidence that SNF1-related kinase and hexokinase are involved in separate sugar-signalling pathways modulating post-translational redox activation of ADP-glucose pyrophosphorylase in potato tubers. Plant J 35:490–500PubMedCrossRefGoogle Scholar
  66. Van Dijken AJH, Schluepmann H, Smeekens SCM (2004) Arabidopsis trehalose-6-phosphate synthase 1 is essential for normal vegetative growth and transition to flowering. Plant Physiol 135:969–977PubMedCrossRefGoogle Scholar
  67. Veyres N, Danon A, Aono M, Galliot S, Byrappa Karibasappa Y, Diet A, Grandmottet F, Tamaoki M, Lesur D, Pilard S, Boitel-Conti M, Sangwan-Norreel BS, Sangwan RS (2008) The Arabiodpsis sweetie mutant is affected in carbohydrate metabolism and defective in the control of growth, development and senescence. Plant J 55:665–686PubMedCrossRefGoogle Scholar
  68. Vogel G, Aeschbacher RA, Müller J, Boller T, Wiemken A (1998) Trehalose-6-phosphate phosphatases from Arabidopsis thaliana: identification by functional complementation of the yeast tps2 mutant. Plant J 13:673–683PubMedCrossRefGoogle Scholar
  69. Vogel G, Fiehn O, Jean-Richard-dit-Bressel L, Boller T, Wiemken A, Aeschbacher RA, Wingler A (2001) Trehalose metabolism in Arabidopsis: occurrence of trehalose and molecular cloning and characterization of trehalose-6-phosphate synthase homologues. J Exp Bot 52:1817–1826PubMedCrossRefGoogle Scholar
  70. Wiemken A (1990) Trehalose in yeast, stress protectant rather than reserve carbohydrate. Antonie Van Leeuwenhoek 58:209–217PubMedCrossRefGoogle Scholar
  71. Wingler A, Roitsch T (2008) Metabolic regulation of leaf senescence: interactions of sugar signalling with biotic and abiotic stress responses. Plant Biol 10:50–62PubMedCrossRefGoogle Scholar
  72. Wingler A, Purdy S, MacLean JA, Pourtau N (2006) The role of sugars in integrating environmental signals during the regulation of leaf senescence. J Exp Bot 57:391–399PubMedCrossRefGoogle Scholar
  73. Wingler A, Masclaux-Daubresse C, Fischer AM(2009) Sugars, senescence and ageing in plants and heterotrophic organisms. J Exp Bot 60:1063–1066PubMedCrossRefGoogle Scholar
  74. Wingler A, Purdy SJ, Edwards SA, Chardon F, Masclaux-Daubresse C (2010) QTL analysis for sugar-regulated leaf senescence supports flowering-dependent and -independent senescence pathways. New Phytol 185:420–433PubMedCrossRefGoogle Scholar
  75. Wingler A, Delatte TL, O’Hare LE, Primavesi LF, Jhurreea D, Paul MJ, Schluepmann H (2012) Trehalose 6-phosphate is required for the onset of leaf senescence associated with high carbon availability. Plant Physiol 158:1241–1251Google Scholar
  76. Wong CE, Singh MB, Bhalla PL (2009) Molecular processes underlying the floral transition in the soybean shoot apical meristem. Plant J 57:832–845PubMedCrossRefGoogle Scholar
  77. Zhang Y, Primavesi LF, Jhurreea D, Andralojc PJ, Mitchell RAC, Powers SJ, Schluepmann H, Delatte T, Wingler A, Paul MJ (2009) Inhibition of Snf1-related protein kinase (SnRK1) activity and regulation of metabolic pathways by trehalose 6-phosphate. Plant Physiol 149:1860–1871PubMedCrossRefGoogle Scholar

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© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Research Department of Genetics, Evolution and EnvironmentUniversity College LondonLondonUK
  2. 2.Plant ScienceRothamsted ResearchHarpendenUK

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