The cytoskeleton of pollen tubes and how it determines the physico-mechanical properties of cell wall

The growth of pollen tubes is a complex process that requires the synchronized activity of many different factors. Pollen tubes grow by penetrating through relatively solid tissues of the pistil. In doing so, pollen tubes need a specialized shape consisting of a tubular axis culminating with a hemispherical dome. In order to maintain such a shape, pollen tubes must build a dynamic cell wall which is highly adapted to the cell's penetrating activity. Therefore, the molecular mechanism controlling the pollen tube architecture is critical. In growing pollen tubes, the cytoskeleton controls the intracellular transport of organelles and vesicles. Movement of membrane-bounded structures is necessary for the apex-constrained growth of pollen tubes and for proper assembly of the cell wall. This process is strictly related to the fine-tuned deposition of specific proteins and polysaccharides, which contribute to local differentiation of cell wall texture and thus to the growth pattern of pollen tubes. This chapter will focus on the molecular relationships between cytoskeleton and cell wall deposition in pollen tubes in order to highlight how the cytoskeleton controls the shaping of pollen tubes.