Developmental and Production Biology – Omics Approaches – Břetislav Brzobohatý

• Molecular mechanisms underlying:

1. hormonal regulation of plant development

2. plant adaptation to abiotic and biotic cues

• Molecular markers related to economically important traits

Determination of molecular mechanisms governing hormonal regulations and their functions in plant development and stress-response. Developmental outputs of cell polarity will be established.

Hormonal control of plant growth correlations and responses to environmental cues

Throughout their life cycle, plants as sessile organisms depend critically on sensing a number of external and internal signals that they use to alter their physiology, morphology and development. Plant hormones, mainly auxin and cytokinin, have been recognised as key players in the control of plant growth correlations, and an increasing body of evidence implicates their involvement in the responses to environmental cues. We will investigate the molecular and cellular mechanisms underlying the hormonal modulation of the plant body architecture, mainly shoot and root branching, under various environmental cues including nutrient and/or water deficiency. Our pilot experiments indicate that alterations in the hormone level or signalling can compensate for the undesirable effects of the environmental cues on plant growth and morphogenesis. We will develop and employ reverse genetic tools to get a deeper understanding of the particular roles of a number of candidate genes implicated in the compensation responses. In addition, green fluorescent protein (GFP) fusions will be used to monitor promoter activities and protein products of genes reportedly involved in branching, for example genes involved in the maintenance and differentiation of the axillary meristems and auxin transport. Based on the knowledge gained in the project we will evaluate the possibilities of crop engineering for better performance under limited nutrient and water availability.

Much progress has been made recently in our understanding of cytokinin biosynthesis and signaling, and how environmental cues interact with these components to modulate plant growth, development and physiology. Cytokinin probably plays a role in the response to many environmental signals. Physiological studies have correlated the changes in cytokinin levels in response to environmental cues. Genome-wide microarray studies reveal overlapping transcriptional responses between cytokinin and various environmental inputs. The components of the cytokinin biosynthetic and signaling pathway are, in turn, transcriptionally altered by environmental stimuli. While many of the links of cytokinin to various environmental stimuli have been simply correlative, recent studies using mutants that alter cytokinin biosynthesis or signalling have begun to demonstrate an important role for cytokinins in these responses. However, because of the wide range of outputs of the cytokinin signalling pathway, dissecting the role of cytokinin in the response to a particular stress remains challenging. We will employ a number of tools now available to alter cytokinin levels and responsiveness in combination with non targeted transcriptomic and proteomic analyses to deepen our knowledge of this subject. The investigation of structure-function relationships in proteins involved in these interactions will provide us with knowledge of their mechanisms of action at the molecular level. We will focus on the interactions of cytokinin and the light, temperature and drought response pathways. We will also examine the effects of altered cytokinin levels and signalling on the accumulation of and tolerance to heavy metals. Attention will be paid to cytokinin interactions with other hormones in these processes. As we further deepen our understanding of the circuitry underlying the input of cytokinin into the response of the environmental signals, we should be able to engineer these pathways to produce plants with increased tolerance to abiotic stresses.