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Pollen tube

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**1. Pollen Tube Structure and Function:**
Pollen tubes transport male gametes in seed plants.
Pollen tube formation is complex and not fully understood.
Pollen tubes rapidly grow down the style, carrying sperm cells.
– Upon reaching the ovule, the pollen tube ruptures for fertilization.
Double fertilization in flowering plants produces zygote and endosperm.

**2. Pollen Tube Growth Mechanisms:**
– Recognition by the female sporophyte of compatible pollen.
– Self-incompatibility systems maintain genetic diversity.
Pollen grain germination and growth of the pollen tube.
– Gene regulation governing pollen growth compatibility.
– Stigma guiding sperm to the receptive ovule for fertilization.

**3. Actin Cytoskeleton in Pollen Tube Growth:**
– Actin cytoskeleton crucial for pollen tube growth.
– Actin filaments arranged into three structures in the tube.
– Regulation of actin cytoskeleton dynamics by actin-binding proteins.
– Actin filament dynamics in the apical region for vesicle targeting.
– Role of actin filaments in pollen tube tip growth and organelle transport.

**4. Evolutionary Aspects of Pollen Tube Development:**
– Transitional features in the evolution of pollen tubes with non-motile sperm.
– Early seed plants with spores and motile sperm evolving into pollen tubes.
– Gymnosperms and their unique pollen tube characteristics.
– Angiosperm pollen tube growth patterns and fertilization mechanisms.
– Evolutionary significance of fast pollen tube growth in various plant species.

**5. Pollen Tube Behavior and Regulation:**
Pollen tubes as a model for plant cell behavior study.
– External cues influencing pollen tube growth during fertilization.
DNA repair mechanisms during pollen tube growth for genomic integrity.
– Role of RMD in pollen tube growth and polarized cell development.
– Regulation of actin cytoskeleton organization and dynamics in pollen tubes.

Pollen tube (Wikipedia)

A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms. In maize, this single cell can grow longer than 12 inches (30 cm) to traverse the length of the pistil.

SEM image of pollen tubes growing from lily pollen grains.

Pollen tubes were first discovered by Giovanni Battista Amici in the 19th century.

They are used as a model for understanding plant cell behavior. Research is ongoing to comprehend how the pollen tube responds to extracellular guidance signals to achieve fertilization.

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