Pollen Systems Biology – How do pollen grains germinate and generate a highly polarized pollen tube?
Although a detailed characterization of single ion transporters helps to understand their specific role during pollen tube growth, a comprehensive view of the entire proteins during germination and tube growth can provide new insights into the polar growth process. Therefore, after studying membrane and membrane-associated proteins in pollen by a membrane proteome analysis (Pertl et al 2009), we identified the lily pollen transcriptome (Lang et al. 2015), which is now used as a customized database for further proteome studies. In addition, specific protein-protein interactions (PM H+ ATPase interactome: Pertl-Obermeyer et al. 2014) are studied as well as metabolic pathways networks (Obermeyer et al. 2013) that dynamically change during germination and growth of pollen tubes. By using this systems biological (multi-omics) approach one may identify and map essential processes pathways and molecules that form the tip growth network = TIPOME.
Osmoreglution – Plants are quite frugal organisms living on a simple diet of light, CO2 and water with a few ions but produce the majority of the food for an increasing global population. Shortage in any of these ‘plant nutrients’ will definitely result in lower crop yields and less food for humans. Recent prospective scenarios for agriculture forecast water shortages due to climate change and at the same time, increased water consumption for agricultural production of human nourishment. The supply of water during the plant’s life is one of the most essential parameters that control crop yield. Limited water supply and a low water potential will cause short- and long-term changes in plant growth and development, e.g. stomata closure and accumulation of solutes, respectively, to retain water and to counteract damaging effects of tissue dehydration. A major challenge for basic plant research will be to understand how plants use water in their organs and how they adapt to water shortages to allow targeted improvements for crop plants in the future. In addition to plant growth, fertilization, especially the male gametophyte (pollen), is highly sensitive to drought stress and failure in fertilization directly reduces crop yields due to lower production of seeds and fruits. So far, we do not know how pollen and the pollen tube in particular, adapt to reduced water availability in the stigma tissue because it needs to take up water continuously to elongate on its way to the ovule.