Desert rhizosphere microbes
To feed the world, food production has to be increased by about 50 % until the year 2050. However, many countries in dry and hot zones already chronically lack the production of enough food for their own population and depend on imports and foreign aid. Considering that harvest losses by drought, salt and heat stresses amounts to approx. 60 % of total productivity, improvement of abiotic stress tolerance is the main aim in crop improvement in the world. All plants have evolved mechanisms to respond to changing environmental conditions (Hirt, 2009), but the ability of a variety of plants to adapt to extreme stress conditions also depends on the association with specific rhizosphere microbes (de Zelicourt et al., 2013; Lugtenberg and Kamilova, 2009).
Therefore, our project aims are:
- Identify the rhizosphere microbes that are associated with plants growing in extreme heat, drought and salt conditions.
- Identify the molecular mechanisms that enable plants to adapt to extreme environmental conditions induced by the microbial association
- Use the appropriate rhizosphere partners to enhance plant stress tolerance and help increase crop food production in a sustainable way.
- de Zelicourt A, Al-Yousif M, Hirt H (2013) Rhizosphere microbes as essential partners for plant stress tolerance. Mol Plant. 6:242-5.
- Hirt, H. (2009) Plant Stress Biology: From Genomics to Systems Biology (Wiley, West Sussex).
- Lugtenberg, B., and Kamilova, F. (2009) Plant-growth-promoting rhizobacteria. Annu. Rev. Microbiol. 63, 541–556
Stress chromatin biology
To feed the 9 billion people in 2050, agricultural production must increase by 50 %. Currently, more than 60 % of world-wide production of crops is lost due to abiotic and biotic conditions. Therefore, one primary goal in breeding is to generate crops with enhanced stress tolerance. So far, plant breeding was mostly based on genetically modifying crop species, but epigenetic approaches for obtaining long term adaptation and transgenerational stress tolerance are emerging concepts that receive increased attention. It is well-known that plants can be primed by biotic and abiotic factors for improved pathogen resistance, stress tolerance and yield and it is conceivable that the priming responses are dependent on long term somatic memory. Although priming has been associated with modificatons at both the protein level of signalling factors (Beckers et al., 2009) and histones (Kumar and Wigge, 2010) as well as at the DNA level by methylation (Dowen et al., 2012), the molecular mechanisms underlying priming of epigenetic stress tolerance are still poorly understood (Conrath, 2011, Gustat and Mittlesten Scheid, 2012, Ventura et al., 2012). Using a novel chromatin purification protocol and high resolution mass spectrometry proteomics, we have identified a large number of chromatin proteins that become rapidly phosphorylated by stress-induced protein kinases in Arabidopsis thaliana. In the context of this project, we now aim to unravel the role of the modification of these chromatin factors in priming stress tolerance. We expect that this knowledge will strongly contribute to a new concept in future crop breeding for stress tolerance.
- G. Beckers, Jaskiewicz M, Liu Y, Underwood WR, He SY, Zhang S, Conrath U. (2009) Mitogen-activated protein kinases 3 and 6 are required for full priming of stress responses in Arabidopsis thaliana. Plant Cell 21, 944–953
- Dowen RH, Pelizzola M, Schmitz RJ, Lister R, Dowen JM, Nery JR, Dixon JE, Ecker JR (2012) Widespread dynamic DNA methylation in response to biotic stress. Proc Natl Acad Sci USA 109, 2183-2191.
- Gutzat R, Mittelsten Scheid O. (2012) Epigenetic responses to stress: triple defense? Curr Opin Plant Biol. 5:568-73.
- Kumar SV, Wigge PA (2010) H2A.Z-containing nucleosomes mediate the thermosensory response in Arabidopsis. Cell 140:136-147.
- Ventura L, Dona M, Macovei A, Carbonera D, Buttafava A, Mondoni A, Rossi G, Balestrazzi A (2012) Understanding the molecular pathways associated with seed vigor. Plant Physiol Biochem 60:196-206.
Stress Response and Signal Transduction of Plants
In contrast to animals, plants are sessile organisms and cannot move away
from adverse environmental conditions. Therefore, plants heavily rely on
high sensitivity detection and adaptation mechanisms to environmental
perturbations. The goals of our research are to understand the molecular
mechanisms of how plants sense, transduce and adapt to changes in
environmental conditions such as UV, cold, drought, heat, salinity, pests
and pathogens. We aim to understand how plants perceive and transmit
stress signals, how plants regulate stress gene expression, and what
function stress metabolites and protein products have in conferring stress
tolerance. We believe that a thorough understanding of these processes
will provide a solid basis to help secure agriculture and environment
under changing global conditions.
Perception and Transduction of Stress Signals
Plants encounter a wide range of abiotic stresses, including
drought, cold, and salt etc., and biotic stresses such as plant
pathogen attacks. To adapt to these stresses, plants use diverse
and sophisticated strategies for recognizing and responding to
these stresses. Sensing of environmental stresses may occur at the
point of initial stress perception itself. Plants might perceive
the stresses in different ways, such as by plasma membrane located
receptors, intracellular or cytoskeleton-associated proteins.
Stress perception is transmitted by signal cascades into altered
gene expression programmes ultimately resulting in metabolic
adjustment and altered physiological responses. Plants have evolved
distinct mechanisms by which tolerance against different stresses
can be achieved. Knowledge about the signal transduction pathways
induced by different stresses is essential to improve plant
tolerance to distinct abiotic and biotic stresses. Although our
understanding of the signalling pathways has increased rapidly over
recent years by joining genetic, biochemical and cell biology
disciplines, we are still far away from a complete understanding
how perception and signalling of environmental stresses is achieved
in plants. Using latest genomic, proteomic and metabolomic
technology, we are searching for sensors and signalling components
of environmental stresses. The major goals of the group are to
elucidate the signalling pathways associated with abiotic and
Regulation of Stress Gene Expression
Plants are capable of adapting to a variety of stresses by
inducing specific sets of genes that play key roles in the
adaptation process of plants against diverse stimuli including
biotic and abiotic stresses. By transcriptome profiling and
phosphoproteomics of defined signalling mutants, we try to uncover
the mechanisms how stress signalling is coupled to the
transcriptional machinery with the ultimate aim for improving plant
stress tolerance. Specific aims are the characterization of the
transcriptional mechanisms in the regulation of reactive oxygen
species involved in abiotic and biotic stresses.
Plant Stress Tolerance: Metabolites and Protein Products
The adaptation mechanisms that provide protection against
abiotic and biotic stresses involve complex responses, including
changes in cell cycle, developmental programmes, as well as the
induction of stress and defense genes and the accumulation of
stress metabolites. The functions of the stress metabolites and
stress protein factors accumulating under particular stresses are
still poorly understood. Using high-end metabolite and proteome
screening techniques, we are trying to identify novel metabolites
and protein factors induced by particular stresses and investigate
their properties in a functional context.