title: Interactions of C4 Subtype Metabolic Activities and Transport in Maize Are Revealed through the Characterization of DCT2 Mutants.
abstract: C4 photosynthesis in grasses requires the coordinated movement of metabolites through two specialized leaf cell types, mesophyll (M) and bundle sheath (BS), to concentrate CO2 around Rubisco. Despite the importance of transporters in this process, few have been identified or rigorously characterized. In maize (Zea mays), DCT2 has been proposed to function as a plastid-localized malate transporter and is preferentially expressed in BS cells. Here, we characterized the role of DCT2 in maize leaves using Activator-tagged mutant alleles. Our results indicate that DCT2 enables the transport of malate into the BS chloroplast. Isotopic labeling experiments show that the loss of DCT2 results in markedly different metabolic network operation and dramatically reduced biomass production. In the absence of a functioning malate shuttle, dct2 lines survive through the enhanced use of the phosphoenolpyruvate carboxykinase carbon shuttle pathway that in wild-type maize accounts for ∼ 25% of the photosynthetic activity. The results emphasize the importance of malate transport during C4 photosynthesis, define the role of a primary malate transporter in BS cells, and support a model for carbon exchange between BS and M cells in maize.
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132.
authors.forename: Sarit
authors.identifier: http://orcid.org/0000-0001-9608-0866
authors.initials: S
authors.lastname: Weissmann
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132.
authors.forename: Fangfang
authors.identifier: http://orcid.org/0000-0001-7220-0675
authors.initials: F
authors.lastname: Ma
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Koki
authors.identifier: http://orcid.org/0000-0003-3623-9075
authors.initials: K
authors.lastname: Furuyama
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132 U.S. Department of Agriculture, Agricultural Research Service, St. Louis, Missouri 63132.
authors.forename: James
authors.identifier: http://orcid.org/0000-0003-1361-723X
authors.initials: J
authors.lastname: Gierse
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132.
authors.forename: Howard
authors.initials: H
authors.lastname: Berg
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shao
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Mitsutaka
authors.identifier: http://orcid.org/0000-0001-6485-2462
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132 U.S. Department of Agriculture, Agricultural Research Service, St. Louis, Missouri 63132 allen@ars.usda.gov tbrutnell@danforthcenter.org.
authors.forename: Doug K
authors.identifier: http://orcid.org/0000-0001-8599-8946
authors.initials: DK
authors.lastname: Allen
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, Missouri 63132 allen@ars.usda.gov tbrutnell@danforthcenter.org.
authors.forename: Thomas P
authors.identifier: http://orcid.org/0000-0002-3581-8211
authors.initials: TP
authors.lastname: Brutnell
mesh_terms: D001692:Biological Transport; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D002736:Chloroplasts / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008293:Malates / Q000378:metabolism; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D002247:Carbon Isotopes; D008293:Malates; D010940:Plant Proteins; D002245:Carbon Dioxide; D002244:Carbon; C030298:malic acid; D012273:Ribulose-Bisphosphate Carboxylase; D019764:Phosphoenolpyruvate Carboxykinase (ATP)
references.citation: Plant J. 2004 Mar;37(6):914-39
references.pmid: 14996223
references.citation: Methods Mol Biol. 2003;236:157-76
references.pmid: 14501064
references.citation: Plant Cell. 2003 Apr;15(4):874-84
references.pmid: 12671084
references.citation: Plant J. 2006 Oct;48(1):45-53
references.pmid: 16925599
references.citation: J Exp Bot. 2014 Jul;65(13):3543-55
references.pmid: 24790109
references.citation: Photosynth Res. 2002;73(1-3):265-72
references.pmid: 16245130
references.citation: Biochim Biophys Acta. 1965 Nov 29;109(2):448-53
references.pmid: 5867546
references.citation: Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16967-72
references.pmid: 25368168
references.citation: Nat Biotechnol. 2010 May;28(5):511-5
references.pmid: 20436464
references.citation: Planta. 1985 May;164(2):179-88
references.pmid: 24249559
references.citation: Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19587-92
references.pmid: 17148605
references.citation: Plant Physiol. 2014 Apr 4;165(2):608-617
references.pmid: 24706552
references.citation: Annu Rev Plant Biol. 2004;55:173-96
references.pmid: 15377218
references.citation: Plant Cell Environ. 2009 Sep;32(9):1211-29
references.pmid: 19389052
references.citation: Plant Physiol. 1985 Sep;79(1):84-9
references.pmid: 16664407
references.citation: Plant Physiol. 1999 Jun;120(2):539-46
references.pmid: 10364405
references.citation: Plant J. 2003 Aug;35(3):316-31
references.pmid: 12887583
references.citation: Biochem Soc Trans. 1996 Aug;24(3):757-61
references.pmid: 8878842
references.citation: Plant Biol (Stuttg). 2012 Jul;14(4):621-9
references.pmid: 22289126
references.citation: Plant Cell Environ. 2012 Mar;35(3):513-23
references.pmid: 21950797
references.citation: Plant Physiol. 2008 Sep;148(1):568-79
references.pmid: 18599648
references.citation: Biochim Biophys Acta. 1977 Dec 23;462(3):603-12
references.pmid: 23151
references.citation: Plant Physiol. 2009 Jan;149(1):195-204
references.pmid: 18805949
references.citation: FEBS J. 2008 Jun;275(12):3193-206
references.pmid: 18479460
references.citation: J Exp Bot. 2014 Jul;65(13):3567-78
references.pmid: 24609651
references.citation: J Exp Bot. 2002 Apr;53(370):979-87
references.pmid: 11912240
references.citation: Trends Plant Sci. 2009 Feb;14(2):100-9
references.pmid: 19162526
references.citation: Biochem J. 1966 Oct;101(1):103-11
references.pmid: 5971771
references.citation: J Integr Plant Biol. 2011 Feb;53(2):120-35
references.pmid: 21205189
references.citation: Plant Cell. 2008 Jul;20(7):1818-32
references.pmid: 18628352
references.citation: Arch Biochem Biophys. 1981 Aug;210(1):82-9
references.pmid: 6271074
references.citation: J Exp Bot. 2011 May;62(9):3103-8
references.pmid: 21511901
references.citation: Biochim Biophys Acta. 1977 Dec 23;462(3):583-602
references.pmid: 23150
references.citation: Genetics. 2005 Feb;169(2):981-95
references.pmid: 15520264
references.citation: Biochem Biophys Res Commun. 1979 Feb 28;86(4):1274-80
references.pmid: 435326
references.citation: Photosynth Res. 2003;77(2-3):191-207
references.pmid: 16228376
references.citation: Ann Bot. 2013 Apr;111(4):577-89
references.pmid: 23388881
references.citation: Plant J. 2011 Jan;65(1):15-26
references.pmid: 21175886
references.citation: Plant Physiol. 1986 May;81(1):115-9
references.pmid: 16664758
references.citation: Bioinformatics. 2010 Apr 1;26(7):873-81
references.pmid: 20147302
references.citation: Plant Cell Physiol. 2004 Feb;45(2):187-200
references.pmid: 14988489
references.citation: Nat Genet. 2010 Dec;42(12):1060-7
references.pmid: 21037569
references.citation: Photosynth Res. 2000;66(3):199-224
references.pmid: 16228420
references.citation: New Phytol. 2004 Feb;161(2):341-370
references.pmid: 33873498
references.citation: Plant Cell. 2010 Nov;22(11):3509-42
references.pmid: 21081695
references.citation: Nat Biotechnol. 2014 Nov;32(11):1158-65
references.pmid: 25306245
references.citation: Plant Physiol. 1985 Sep;79(1):165-70
references.pmid: 16664363
references.citation: Planta. 1992 May;187(2):242-6
references.pmid: 24178051
references.citation: Planta. 2000 Nov;211(6):800-6
references.pmid: 11144264
references.citation: Plant Physiol. 2011 Jan;155(1):43-8
references.pmid: 20855521
references.citation: Curr Opin Plant Biol. 2010 Jun;13(3):257-65
references.pmid: 20188622
references.citation: Biochem J. 1971 Nov;125(2):425-32
references.pmid: 5144745
references.citation: Nature. 2011 Aug 24;476(7361):472-5
references.pmid: 21866161
references.citation: Ann Bot. 2005 Dec;96(7):1307-14
references.pmid: 16243851
references.citation: Am J Bot. 2007 Mar;94(3):362-81
references.pmid: 21636407
references.citation: Plant Physiol. 1990 Nov;94(3):950-9
references.pmid: 16667876
references.citation: Plant Physiol. 2012 Sep;160(1):165-77
references.pmid: 22829318
references.citation: Plant Physiol. 1949 Jan;24(1):1-15
references.pmid: 16654194
references.citation: Front Plant Sci. 2015 Feb 26;6:106
references.pmid: 25767475
references.citation: Planta. 1975 Jan;125(3):273-9
references.pmid: 24435440
references.citation: Plant Cell. 2011 Dec;23(12):4208-20
references.pmid: 22186372