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The role of signaling phospholipids in the regulation of plant polar growth
Pleskot, Roman ; Potocký, Martin (advisor) ; Testerink, Christa (referee) ; Spiwok, Vojtěch (referee)
Polar cell growth is one of the most fundamental processes in plant development. Pollen tubes represent excellent experimental system to study basic rules of this phenomenon. Polar growth is governed by a precise spatiotemporal coordination of various molecules, such as small GTPases, actin cytoskeleton, protein kinases and reactive oxygen species, to achieve its establishment and maintenance. In this study, we utilized a combination of diverse experimental approaches together with advanced computational methods to investigate the role of two signaling phospholipids, phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphophate (PIP2) in the polar growth. We described the involvement of PA in the regulation of actin cytoskeleton, which dynamics is essential for the proper pollen tube growth. We found direct interaction of actin with the PA-producing enzyme, phospholipase D (PLDβ)1 and we showed that actin affects the activity of PLDβ. We further described structural details of the PA inhibition of actin-capping protein and we proposed the model of positive- feedback loop of the actin dynamics regulation by PA and PLDβ1. To get insight into the PA localization in pollen tubes, we prepared PA-binding domain of Spo20p as YFP-fusion protein and we used it as PA-biosensor. We found that PA is enriched...
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