Reproduction, sexual or asexual, is a means of survival of a particular species on the face of a planet. Angiosperms have many ways of reproducing themselves. It is of no surprise that the sex organs of a plant are in their flowers. Two major organs being: ovary and the anthers. Pollen is found primarily on the anthers, pollen [male gametophyte] is so widespread that we can find it almost everywhere, in the air we breathe, the soil we walk on etc. Physically it looks like a yellow, white or blue powdery substance.
Pollen develops within the anther and after attaining maturity falls [by the means of air currents etc] onto the receptive stigma. The stored ‘goodies’ and RNA kick into action and start the most probably the most rapid growth of any plant cell. A tube known as the pollen tube grows from each pollen grain. This pollen tube grows toward the embryo sac. Eventually two sperm cells are deposited into the embryo sac where they fuse with the egg and form a zygote. Pollen germination is one of the most important processes insuring that a zygote is formed and the plant species continues and does not become extinct.
Pollen germination is the stage when the pollen falls on the stigma and start growing the pollen tube. This process is vital since the ovary is located at the very bottom of the anther and is concealed from all 4 sides, making it almost impossible for the sperms cell to find the ovary on their own. Pollen germination is kind of like an oil rig drilling toward the ovary to deliver the sperm cells. The eukaryotic cytoplasm has a set of long, thin fibers called the cytoskeleton, which fill many important functions [Life, The science of biology, 2001].
One of the most important functions that the cytoplasm accomplishes is during reproduction. The cytoplasm provides shape and support, the most important component of the cytoskeleton is the microfilaments [7nm in diameter]. Microtubules are oriented to the long axis of the pollen tube and are cross bridged to the plasma membrane. This indicates that the microtubules support and possibly assist in transportation needs of the two sperm cells. Thus the hypotheses of this experiment being that the actin microfilament are important to pollen tube growth.
Therefore the prediction would be that if actin microfilaments are important to the pollen tube growth, then pollen growth in media with cytochalisin B [powerful inhibitor] should have less pollen tube growth than pollen germinated in media with cytochalisin B [Lab notebook, pg 4-6]. The hypothesis was tested by setting up a simple experiment. The experiment consisted of two media both with pollen grains; the only difference is the presence of cytochalisin B in one of the media cultures.
At the end of the experiment [approximately ~1-1.5hrs] it was concluded/ predictions confirmed [supported, not proven] by viewing through a light microscope that the media with cytochalisin B had less pollen tube growth. Therefore actin microfilaments are involved in the transport of secretory vesicles essential for cell elongation [Taylor & Hepler, 1997]. The one and only fundamental reason why this experiment was conducted is so that our theory that actin microfilaments are important in the plant kingdom too- in pollen tube germination.
Literature Cited:
1. William K. Purves, David Sadava, Gordon H. Orians, H. Craig Heller. 2001. Life The science of biology. Published by W. H. Freeman and company. Copyright (c) 2001 by Sinauer associates, Inc. All rights reserved. Volume I, III. 2. BGYA01 Introductory Biology 2002-2003 Laboratory manual. 1st Quarter. Author/s unkown. 3. Loverine P. Taylor Peter K. Hepler Annu. Rev. Plant Physiol. Plant Mol. Biol. 1997. 48:461-91 Copyright (c) 1997 by Annual Reviews Inc.