Publications of NIPGR Scientists

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Author: search.filters.author.Fernie, Alisdair R.Subject: search.filters.subject.Arabidopsis thaliana

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    Serine hydroxymethyltransferase6 is involved in growth and resistance against pathogens via ethylene and lignin production in Arabidopsis
    (John Wiley & Sons, 2024) Singh, Pooja; Kumari, Aprajita; Khaladhar, Vemula Chandra; Singh, Namrata; Pathak, Pradeep Kumar; Kumar, Vinod; Kumar, Ritika Jantu; Jain, Priyanka; Thakur, Jitendra K.; Fernie, Alisdair R.; Bauwe, Hermann; Raghavendra, A.S.; Gupta, Kapuganti Jagadis
    Photorespiratory serine hydroxymethyltransferases (SHMTs) are important enzymes of cellular one-carbon metabolism. In this study, we investigated the potential role of SHMT6 in Arabidopsis thaliana. We found that SHMT6 is localized in the nucleus and expressed in different tissues during development. Interestingly SHMT6 is inducible in response to avirulent, virulent Pseudomonas syringae and to Fusarium oxysporum infection. Overexpression of SHMT6 leads to larger flowers, siliques, seeds, roots, and consequently an enhanced overall biomass. This enhanced growth was accompanied by increased stomatal conductance and photosynthetic capacity as well as ATP, protein, and chlorophyll levels. By contrast, a shmt6 knockout mutant displayed reduced growth. When challenged with Pseudomonas syringae pv tomato (Pst) DC3000 expressing AvrRpm1, SHMT6 overexpression lines displayed a clear hypersensitive response which was characterized by enhanced electrolyte leakage and reduced bacterial growth. In response to virulent Pst DC3000, the shmt6 mutant developed severe disease symptoms and becomes very susceptible, whereas SHMT6 overexpression lines showed enhanced resistance with increased expression of defense pathway associated genes. In response to Fusarium oxysporum, overexpression lines showed a reduction in symptoms. Moreover, SHMT6 overexpression lead to enhanced production of ethylene and lignin, which are important components of the defense response. Collectively, our data revealed that SHMT6 plays an important role in development and defense against pathogens.
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    Nitrate nutrition influences multiple factors in order to increase energy efficiency under hypoxia in Arabidopsis
    (Oxford University Press, 2019) Wany, Aakanksha; Gupta, Alok Kumar; Kumari, Aprajita; Mishra, Sonal; Singh, Namrata; Pandey, Sonika; Vanvari, Rhythm; Igamberdiev, Abir U.; Fernie, Alisdair R.; Gupta, Kapuganti Jagadis
    BACKGROUND AND AIMS: Nitrogen (N) levels vary between ecosystems, while the form of available N has a substantial impact on growth, development and perception of stress. Plants have the capacity to assimilate N in the form of either nitrate (NO3-) or ammonium (NH4+). Recent studies revealed that NO3- nutrition increases nitric oxide (NO) levels under hypoxia. When oxygen availability changes, plants need to generate energy to protect themselves against hypoxia-induced damage. As the effects of NO3- or NH4+ nutrition on energy production remain unresolved, this study was conducted to investigate the role of N source on group VII transcription factors, fermentative genes, energy metabolism and respiration under normoxic and hypoxic conditions. METHODS : We used Arabidopsis plants grown on Hoagland medium with either NO3- or NH4+ as a source of N and exposed to 0.8 % oxygen environment. In both roots and seedlings, we investigated the phytoglobin-nitric oxide cycle and the pathways of fermentation and respiration; furthermore, NO levels were tested using a combination of techniques including diaminofluorescein fluorescence, the gas phase Griess reagent assay, respiration by using an oxygen sensor and gene expression analysis by real-time quantitative reverse transcription-PCR methods. KEY RESULTS : Under NO3- nutrition, hypoxic stress leads to increases in nitrate reductase activity, NO production, class 1 phytoglobin transcript abundance and metphytoglobin reductase activity. In contrast, none of these processes responded to hypoxia under NH4+ nutrition. Under NO3- nutrition, a decreased total respiratory rate and increased alternative oxidase capacity and expression were observed during hypoxia. Data correlated with decreased reactive oxygen species and lipid peroxidation levels. Moreover, increased fermentation and NAD+ recycling as well as increased ATP production concomitant with the increased expression of transcription factor genes HRE1, HRE2, RAP2.2 and RAP2.12 were observed during hypoxia under NO3- nutrition. CONCLUSIONS: The results of this study collectively indicate that nitrate nutrition influences multiple factors in order to increase energy efficiency under hypoxia.
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    Establishment of a photoautotrophic cell suspension culture of Arabidopsis thaliana for photosynthetic, metabolic, and signaling studies
    (Oxford University Press, 2012) Hampp, Christine; Richter, Andreas; Osorio, Sonia; Zellnig, Gunther; Sinha, Alok Krishna; Jammer, Alexandra; Fernie, Alisdair R.; Grimm, Bernhard; Roitsch, Thomas
    Plant cell suspension cultures have been used as model sys- tems to circumvent the problems associated with the analyses of a multi-factorial plant that is composed of multiple tissue and cell types exposed to diverse signals. A number of plant suspension cultures have proven to be valuable to study vari- ous topics including defense response, secondary metabolite formation, ion transport, gene regulation, and signal trans- duction (Roitsch and Sinha, 2002 and references therein). How- ever, most cultures reported to date, including the cultures from model species such as Arabidopsis (Christie and Jenkins, 1996), require the presence of sugar in the medium and are characterized by no or negligible photosynthetic activity (Roitsch and Sinha, 2002). For only a very limited number of species, such as Chenopodium rubrum, have true photoauto- trophic (PA) cultures been established (see references in Roitsch and Sinha, 2002). Such cultures combine the advan- tages of plant suspension cultures with carbon autotrophy and represent very powerful model systems for plant research. Unfortunately, for as-yet unknown reasons, it is very difficult to establish PA cultures (Widholm, 1992); hence, PA cultures from only a few crop species have been established. PA cul- tures have, however, been used to address various aspects of photosynthesis, herbicide effects, and secondary product formation from exclusively chloroplast localized pathways as well as in characterization of the metabolic changes occurring during the source–sink transition (Roitsch et al., 1995) and the coordinated regulation of primary metabolism and defense responses (Ehness et al., 1997). In parallel, a large number of mutant and transgenic Arabidopsis plants have been char- acterized with respect to their physiology, biochemistry, and molecular biology. That said, the establishment of a PA cell culture of Arabidopsis has, to date, proven elusive.