The Arabidopsis E1 subunit of the 2-oxoglutarate dehydrogenase complex modulates plant growth and seed production
- 102 Downloads
Isoforms of 2-OGDH E1 subunit are not functionally redundant in plant growth and development of A. thaliana.
The tricarboxylic acid cycle enzyme 2-oxoglutarate dehydrogenase (2-OGDH) converts 2-oxoglutarate (2-OG) to succinyl-CoA concomitant with the reduction of NAD+. 2-OGDH has an essential role in plant metabolism, being both a limiting step during mitochondrial respiration as well as a key player in carbon–nitrogen interactions. In Arabidopsis thaliana two genes encode for E1 subunit of 2-OGDH but the physiological roles of each isoform remain unknown. Thus, in the present study we isolated Arabidopsis T-DNA insertion knockout mutant lines for each of the genes encoding the E1 subunit of 2-OGDH enzyme. All mutant plants exhibited substantial reduction in both respiration and CO2 assimilation rates. Furthermore, mutant lines exhibited reduced levels of chlorophylls and nitrate, increased levels of sucrose, malate and fumarate and minor changes in total protein and starch levels in leaves. Despite the similar metabolic phenotypes for the two E1 isoforms the reduction in the expression of each gene culminated in different responses in terms of plant growth and seed production indicating distinct roles for each isoform. Collectively, our results demonstrated the importance of the E1 subunit of 2-OGDH in both autotrophic and heterotrophic tissues and suggest that the two E1 isoforms are not functionally redundant in terms of plant growth in A. thaliana.
Keywords2-oxoglutarate Carbon metabolism Nitrogen metabolism Respiration Seedlings TCA cycle
This work was supported by funding from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) [Grant 306818/2016-7 to ANN; Grant 402511/2016-6 to WLA], the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) [Grant– CEX - APQ-02985-14] and the Max Planck Society to ANN and WLA. Research fellowships granted by CNPq to ANN and WLA and scholarship provided by FAPEMIG to DBM are also gratefully acknowledged. J.C.A. wish to thank also the research fellowship granted by Programa de Estudantes-Convênio de Pós-Graduação (CNPq, PEC-PG).
JACA screened and genotyped the mutant lines and performed the cloning and plant transformation under supervision of AN-N; JACA also performed all experiments; WBS, DBM, JRV, LMLV and JLPD performed complementary experiments and analysis; JACA and ANN designed the experiments and analyzed the data; ANN and WLA conceived the project; JACA, WBS and ANN wrote the article with contributions of all the authors; ARF, EH and WLA complemented the writing.
- Araújo WL, Nunes-Nesi A, Osorio S et al (2011) Antisense inhibition of the iron-sulphur subunit of succinate dehydrogenase enhances photosynthesis and growth in tomato via an organic acid-mediated effect on stomatal aperture. Plant Cell 23:600–627. https://doi.org/10.1105/tpc.110.081224 Google Scholar
- Feria Bourrellier AB, Ferrario-méry S, Vidal J, Hodges M (2009) Biochemical and biophysical research communications metabolite regulation of the interaction between Arabidopsis thaliana PII and N -acetyl- L -glutamate kinase. Biochem Biophys Res Commun 387:700–704. https://doi.org/10.1016/j.bbrc.2009.07.088 Google Scholar
- Gauthier PPG, Bligny R, Gout E et al (2010) In folio isotopic tracing demonstrates that nitrogen assimilation into glutamate is mostly independent from current CO2 assimilation in illuminated leaves of Brassica napus. New Phytol 185:988–999. https://doi.org/10.1111/j.1469-8137.2009.03130.x Google Scholar
- Gibon Y, Bläsing OE, Palacios-Rojas N et al. (2004) Adjustment of diurnal starch turnover to short days: depletion of sugar during the night leads to a temporary inhibition of carbohydrate utilization, accumulation of sugars and post-translational activation of ADP-glucose pyrophosphorylase in the following light period. Plant J 39:847–862. https://doi.org/10.1111/j.1365-313X.2004.02173.x Google Scholar
- Hunt R (1982) Plant growth curves: the functional approach to plant growth analysis. Arnold, LondonGoogle Scholar
- Kromer S (1995) Respiration during photosynthesis. Annu Rev Plant Physiol Plant Mol Bio 46:45–70. https://doi.org/10.1146/annurev.pp.46.060195.000401 Google Scholar
- Landschütze V, Willmitzer L, Müller-Röber B (1995) Inhibition of flower formation by antisense repression of mitochondrial citrate synthase in transgenic potato plants leads to a specific disintegration of the ovary tissues of flowers. EMBO J 14:660–666Google Scholar
- Liao Y, Tian M, Zhang H et al (2015) Salicylic acid binding of mitochondrial alpha-ketoglutarate dehydrogenase E2 affects mitochondrial oxidative phosphorylation and electron transport chain components and plays a role in basal defense against tobacco mosaic virus in tomato. New Phytol 205:1296–1307. https://doi.org/10.1111/nph.13137 Google Scholar
- Luedemann A, von Malotky L, Erban A, Kopka J (2012) TagFinder: preprocessing software for the fingerprinting and the profiling of gas chromatography–mass spectrometry based metabolome analyses. In: Hardy NW, Hall RD (eds) Plant metabolomics: methods and protocols. Humana Press, Totowa, NJ, pp 255–286Google Scholar
- Millar AH, Whelan J, Soole KL, Day DA (2011) Organization and regulation of mitochondrial respiration in plants. Annu Rev Plant Biol 62:79–104. https://doi.org/10.1146/annurev-arplant-042110-103857 Google Scholar
- Murashige T, Skoog F (1962) A revised medium for rapid growth and bio assays with tobacco tissue cultures. Physiol Plant 15:473–497. https://doi.org/10.1111/j.1399-3054.1962.tb08052.x Google Scholar
- Omena-Garcia RP, Araújo WL, Gibon Y et al (2017) Measurement of tricarboxylic acid cycle enzyme activities in plants. In: Jagadis Gupta K (ed) Plant respiration and internal oxygen: methods and protocols. Springer, New York, pp 167–182Google Scholar
- Porra RJ, Thompson WA, Kriedemann PE (1989) Determination of accurate extinction coefficients and simultaneous-equations for assaying chlorophyll-a and chlorophyll-b extracted with 4 different solvents—verification of the concentration of chlorophyll standards by atomic-absorption spectroscopy. Biochim Biophys Acta 975:384–394. https://doi.org/10.1016/S0005-2728(89)80347-0 Google Scholar
- Restovic F, Espinoza-Corral R, Gómez I et al (2017) An active mitochondrial complex II present in mature seeds contains an embryo-specific iron–sulfur subunit regulated by ABA and bZIP53 and is involved in germination and seedling establishment. Front Plant Sci 8:1–13. https://doi.org/10.3389/fpls.2017.00277 Google Scholar
- Sienkiewicz-Porzucek A, Nunes-Nesi A, Sulpice R et al (2008) Mild reductions in mitochondrial citrate synthase activity result in a compromised nitrate assimilation and reduced leaf pigmentation but have no effect on photosynthetic performance or growth. Plant Physiol 147:115–127. https://doi.org/10.1104/pp.108.117978 Google Scholar
- Watanabe M, Balazadeh S, Tohge T, Erban A, Giavalisca P, Kopka J, Mueller-Roeber B, Fernie AR, Hoefgen R (2013) Comprehensive dissection of spatiotemporal metabolic shifts in primary, secondary, and lipid metabolism during developmental senescence in Arabidopsis. Plant Physiol 162:1290–1310. https://doi.org/10.1104/pp.113.217380 Google Scholar