Correction: Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform
[This corrects the article DOI: 10.1371/journal.pone.0168138.].
Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform
Pollen tubes are used as a model in the study of plant morphogenesis, cellular differentiation, cell wall biochemistry, biomechanics, and intra- and intercellular signaling. For a “systems-understanding” of the bio-chemo-mechanics of tip-polarized growth in pollen tubes, the need for a versatile, experimental assay platform for quantitative data collection and analysis is critical. We introduce a Lab-on-a-Chip (LoC) concept for high-throughput pollen germination and pollen tube guidance for parallelized optical and mechanical measurements. The LoC localizes a large number of growing pollen tubes on a single plane of focus with unidirectional tip-growth, enabling high-resolution quantitative microscopy. This species-independent LoC platform can be integrated with micro-/nano-indentation systems, such as the cellular force microscope (CFM) or the atomic force microscope (AFM), allowing for rapid measurements of cell wall stiffness of growing tubes. As a demonstrative example, we show the growth and directional guidance of hundreds of lily (Lilium longiflorum) and Arabidopsis (Arabidopsis thaliana) pollen tubes on a single LoC microscopy slide. Combining the LoC with the CFM, we characterized the cell wall stiffness of lily pollen tubes. Using the stiffness statistics and finite-element-method (FEM)-based approaches, we computed an effective range of the linear elastic moduli of the cell wall spanning the variability space of physiological parameters including internal turgor, cell wall thickness, and tube diameter. We propose the LoC device as a versatile and high-throughput phenomics platform for plant reproductive and development biology using the pollen tube as a model.
Sperm Delivery in Flowering Plants: The Control of Pollen Tube Growth
ABSTRACT Although most people think of pollen merely as an allergen, its true biological function is to facilitate sexual reproduction in flowering plants. The angiosperm pollen grain, upon arriving at a receptive stigma, germinates, producing a tube that extends through the style to deliver its cargo to the ovule, thereby fertilizing the egg, and completing the life cycle of the plant. The pollen tube grows rapidly, exclusively at its tip, and produces a cell that is highly polarized both in its outward shape and its internal cytoplasmic organization. Recent studies reveal that the growth oscillates in rate. Many underlying physiological processes, including ionic fluxes and energy levels, also oscillate with the same periodicity as the growth rate, but usually not with the same phase. Current research focuses on these phase relationships in an attempt to decipher their hierarchical sequence and to provide a physiological explanation for the factors that govern pollen tube growth.