Ranju Chutia

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49-17645753499

Assam Agricultural University, Jorhat

Martin Luther University, Halle- Wittenberg, Germany

Leibniz Institute of Plant Biochemistry, Department of Molecular Signal Processing, Halle (Saale), Germany

01.10.2014-30.09.2017

During my Ph.D. research, I have worked on two different projects. 

1) Regulation of phosphate deficiency-induced metabolic changes in Arabidopsis thaliana

Most of the agricultural soils are deficient in phosphate (Pi) due to its low diffusion rate and its propensity to form complexes with aluminum, iron, calcium, and magnesium depending on soil pH. In order to cope with Pi deficiency, plants adjust their metabolism to efficiently use and acquire phosphate from soil. Additional adaptations involve an alteration in the root system architecture, in which iron (Fe) availability is known to play a very important role. Several regulators are described which plays a very important role in Pi and Fe deficiency responses, however, the involvement of these factors with respect to changes at metabolic levels is not yet known with the exception of only a few of them. Moreover, the effect of simultaneous depletion of Pi and Fe at metabolic levels has not been addressed so far. The first objective of this project was to investigate changes in the level of some metabolites like amino acids, organic acids, and coumarins under Pi, Fe, and combined deficiency conditions. The data showed that many metabolites, which accumulate after phosphate starvation are decreased after iron or combined deficiencies and vice versa. The second objective was to identify those factors which are responsible for observed metabolic changes. For this, several mutants which are defective in genes involved in Pi and Fe deficiency responses were included and subjected to Pi, Fe, and combined deficiency conditions. We could identify some transcription factors which play a role in the crosstalk between phosphate and iron deficiency.

2) Manipulation of malate biosynthesis and exudation in Arabidopsis thaliana

Exudation of organic acids as part of the plant's systemic response to Pi deprivation has already been known through studies on crops like soybean, wheat, and non-crop species like white lupin and Arabidopsis. Organic acids which are exuded facilitate the solubilization of phosphate from insoluble phosphate complexes. Increased biosynthesis and exudation of organic acids is often associated with enhanced activities of enzymes like phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenases (MDH). PEPCs catalyzes the irreversible conversion of phosphoenolpyruvate to oxaloacetate which is then converted to malate by MDHs. PEPCs are under the regulatory control of phosphoenolpyruvate carboxylase kinases (PPCK) which phosphorylates PEPCs and render them insensitive to malate. The main objective of this project was to elucidate the contribution of PEPCs and PPCKs to Pi deficiency-induced organic acid exudation. Moreover, further emphasis was given to investigate whether manipulation of this pathway either by over or under-expression of PPCKs has some effect on malate biosynthesis and exudation and ultimately to internal Pi levels. Our results showed that mutants with impaired PPCK1 expression has reduced malate levels in roots compared to wild-type Col0 both under +Pi and –Pi conditions. Moreover, we could successfully generate transgenic lines overexpressing PPCK1 and PPCK2 which showed higher malate biosynthesis and exudation rate. 

Ziegler J, Schmidt S, Chutia R, Müller J, Böttcher C, Strehmel N, Scheel D, Abel S 2016. Non-targeted profiling of semi-polar metabolites in Arabidopsis root exudates uncovers a role for coumarin secretion and lignification during the local response to phosphate limitation. Journal of Experimental Botany 67, 1421-1432. (Impact factor- 5.830)

Chutia R, Ziegler J, Abel S 2016. Regulation of phosphate starvation induced metabolic changes in Arabidopsis thaliana. Poster presented at the 30th Conference on Molecular Biology of Plants (February, 2017), Dabringhausen, Germany.

Chutia R, Ziegler J, Abel S 2016. Regulation of phosphate starvation induced metabolic changes in Arabidopsis thaliana. Talk presented at the 12th Plant Science Student Conference (July, 2016), IPK Gatersleben.

Chutia R, Ziegler J, Abel S 2016. Regulation of phosphate starvation induced metabolic changes in Arabidopsis thaliana. Poster presented at the 11th Plant Science Student Conference (June, 2015), IPB Halle.

Literature Seminar with title- Small glycosylated lignin oligomers are stored in Arabidopsis leaf vacuoles was presented in the Wednesday seminar series of IPB on 09.03.2016

Research Seminar on Manipulation of malate biosynthesis and exudation was presented in the Wednesday seminar series of IPB on 24.01.2018

Attended the 10th International Metabolomics Workshop, 2017 at Leiden, Netherlands

PhD student at IPB, Halle