We are interested in the roles of reactive oxygen species (ROS), and more specifically hydrogen peroxide, in plant stress responses and programmed cell death. Forward and reverse genetics are employed to unravel the mechanisms of programmed cell death in Arabidopsis thaliana. We have developed two cell death systems, one based on the fungal AAL toxin interfering with spingolipid metabolism and the other based on the catalase inhibitor 3-aminotriazole that elevates H2O2 levels. Plants with reduced catalase activity exhibit oxidative stress symptoms and eventually undergo cell death when exposed to moderate light intensities.

Microarray analysis of AAL toxin and H2O2 induced programmed cell death revealed a number of genes highly regulated in a similar fashion. Comparative bioinformatics analysis with other publicly available databases from experiments leading to oxidative stress/cell death have identified genes that can serve as markers for oxidative stress and other genes, including transcription factors, that are specific for different types of ROS. Knockout mutants of some of those genes are being studied in order to functionally characterize the role of these genes in programmed cell death.

Furthermore, we used AAL toxin and H2O2 to screen T-DNA and EMS mutagenized populations for mutants with altered sensitivity to the two cell death stimuli. The screening resulted in identification of a number of mutants more tolerant to ROS-induced cell death. Given the interconnection between oxidative and abiotic stress, these mutants are being evaluated for abiotic stress tolerance in order to increase our understanding about stress tolerance and cell death in higher plants.

List of selected publications:

Gadjev IZ, Stone JM, Gechev TS (2007) Programmed cell death in plants: new insights into redox regulation and the role of hydrogen peroxide. Int. Rev. Cell Mol. Biol. (in press)

Janknegt PJ, Rijstenbilb JW, van de Poll WH, Gechev TS, Buma AGJ (2007) A comparison of quantitative and qualitative speroxide dismutase assays for application to low temperature microalgae. J. Photochem. Photobiol. 87(3): 218-226

Gechev T, Van Breusegem F, Stone J, Denev I, Laloi C (2006) Reactive oxygen species as signals controlling plant stress responses and programmed cell death. BioEssays 28 (11): 1091-1101

Gadjev I, Vanderauwera S, Gechev T, Laloi C, Minkov I, Shulaev V, Apel K, Inzé D, Mittler R, Van Breusegem F (2006) Transcriptomic footprints disclose specificity of reactive oxygen species signaling in Arabidopsis. Plant Physiology 141: 436-445

Gechev T, Minkov I, Hille J (2005) Hydrogen peroxide-induced cell death in Arabidopsis: transcriptional and mutant analysis reveals a role of an oxoglutarate-dependent dioxygenase gene in the cell death process. IUBMB Life 57: 181-188

Denev ID, Yahubyan GT, Minkov IN, Sundqvist C. (2005) Organization of protochlorophyllide oxidoreductase in prolamellar bodies isolated from etiolated carotenoid-deficient wheat leaves as revealed by fluorescence probes. Biochim Biophys Acta 1716(2): 97-103

Gechev T, Hille J (2005) Hydrogen peroxide as a signal controlling plant programmed cell death. J. Cell Biol. 168(1): 17-20

Herrero S1, Gechev T1, Bakker P, Moar W, de Maagd R (2005) Bacillus thuringiensis Cry1Ca-resistant Spodoptera exigua lacks expression of one of four aminopeptidase N genes. BMC Genomics 6: 96

1shared first authorship

Gechev T, Gadjev I, Dukiandjiev S, Minkov I (2005) Reactive oxygen species as signaling molecules controlling stress adaptation and programmed cell death in plants. In Handbook of Photosynthesis, third edition. M. Pessarakli (Ed.), Taylor&Francis 2nd ed., Boca Raton, USA. p.209-220

Gechev TS, Gadjev IZ, Hille J (2004) An extensive microarray analysis of AAL-toxin-induced cell death in Arabidopsis thaliana brings new insights into the complexity of programmed cell death in plants. Cell. Mol. Life Sci. 61 (10): 1185-1197

Vandenabeele S, Van Der Kelen K, Dat J, Gadjev I, Boonefaes T, Morsa S, Rottiers P, Slooten L, Van Montagu M, Zabeau M, Inze D, Van Breusegem F. (2003) A comprehensive analysis of hydrogen peroxide-induced gene expression in tobacco. Proc. Natl. Acad. Sci. USA. 100(26): 16113-16118

Gechev T, Willekens H, Van Montagu M, Inzé D, Van Camp W, Toneva V, Minkov I (2003) Different responses of tobacco antioxidant enzymes to light and chilling stress. J. Plant Physiol. 160 (5): 509-515

Markham J, Spassieva S, Gechev T, Ferwerda M, Hille J (2003) The necrotrophic pathogen Alternaria alternata f.sp. lycopersici controls programmed cell death through sphingolipid metabolism during infection in tomato. Keystone symposia in Plant Biology, Snowbird, USA, p. 40

Toneva VT, Shalygo NV, Voronetskaya VV, Averina NG, Gechev TS, Minkov IN (2002) Investigation of the porphyrins accumulation in barley leaves incubated with Mn2+ cations and delta-aminolevulinic acid. J. Plant Physiol. 159 (10): 1047-1053

Markham J, Spassieva S, Gechev T, Hille J (2002) Patent application no. 02079201.6: Method to assess gene functionality.

Gechev T, Gadjev I, Van Breusegem F, Inzé D, Dukiandjiev S, Toneva V, Minkov I (2002) Hydrogen peroxide protects tobacco from oxidative stress by inducing a set of antioxidant enzymes. Cell. Mol. Life Sci. 59 (4): 708-714

Staff involved:

Name Position Main research interest
Dr. Tsanko GechevResearch group leaderPlant Biochemistry, Oxidative stress
Dr. Ilia GadjevPost Dr.Plant Biochemistry, Oxidative stress
Dr. Ilia DenevAssistant ProfessorParasitic plants-host interaction,  Plant Stress
Vessela RadevaPhD studentOxidative Plant Stress
Nikolaj MehterovPhD studentOxidative Plant Stress