The key difference between generative nucleus and pollen tube nucleus is that generative nucleus is one of the two male nuclei of seed plants that fuses with the female nucleus in the embryo sac while pollen tube nucleus is the nucleus that guides pollen tube to grow along the pistil into the female embryo sac.
Transferring of pollen from anther to stigma is known as pollination. Once pollens land on the surface of the stigma, pollens start germination and transport male nuclei towards the female nucleus for fertilization. When they germinate, each pollen grain grows a pollen tube into the stigmatic tissue, and male gametes move along the pollen tube. The pollen tube is a tubular structure formed by the male gametophyte of seed plants. It consists of one tube nucleus and two generative nuclei. Generative nuclei are the male nuclei. The tube nucleus guides male nuclei to travel along the style to the embryo sac, which is the female gametophyte of angiosperms. Once male nuclei enter the embryo sac, double fertilization takes place in angiosperms.
CONTENTS
1. Overview and Key Difference
2. What is Generative Nucleus
3. What is Pollen Tube Nucleus
4. Similarities Between Generative Nucleus and Pollen Tube Nucleus
5. Side by Side Comparison – Generative Nucleus vs Pollen Tube Nucleus in Tabular Form
6. Summary
What is Generative Nucleus?
Generative nuclei are the male gametes that will unite with the female nuclei in the embryo sac. There are two generative nuclei in each pollen tube. They are haploid nuclei, and they originate when the pollen grain nucleus is divided by mitosis.
Figure 01: Double Fertilization
Generally, angiosperms undergo double fertilization. Hence, both generative nuclei fuse separately with female nuclei. One male generative nucleus fuses with the egg nucleus to form the zygote. Second male generative nucleus fuses with two polar nuclei to form the triploid endosperm. Triploid endosperm will provide energy for the embryo’s growth and development.
What is Pollen Tube Nucleus?
Pollen tube nucleus is the nucleus that guides the pollen tube to grow along the pistil into the female gametophyte (embryo sac). Moreover, pollen tube nucleus controls the growth of the pollen tube. Similar to generative nuclei, pollen tube nucleus are also haploid. Moreover, it originates when the pollen grain nucleus is divided by mitosis.
Figure 02: Pollen Tube
Pollen tube nucleus is very important since it is the nucleus that guides pollen tube growth, entering of pollen tube via micropyle into the embryo sac and carry male nuclei for fertilization. Once the pollen tube reaches the ovule, it bursts out delivering male nuclei.
What are the Similarities Between Generative Nucleus and Pollen Tube Nucleus?
- Generative nucleus and pollen tube nucleus are two types of nuclei found inside the pollen tube.
- Both, the generative nucleus and pollen tube nucleus are originated when the pollen grain nucleus is divided by mitosis.
- Both nuclei are haploid.
- Generative nucleus and pollen tube nucleus are found in angiosperms during sexual reproduction.
What is the Difference Between Generative Nucleus and Pollen Tube Nucleus?
The generative nucleus is one of the two male nuclei of seed plants that undergo fertilization. Pollen tube nucleus is the nucleus that guides the growth of the pollen tube through the pistil. So, this is the key difference between generative nucleus and pollen tube nucleus. In each pollen tube, there are two generative nuclei and only one pollen tube nucleus. Moreover, generative nuclei fuse with female nuclei while pollen tube nucleus does not fuse with female nuclei.
The below infographic tabulates more differences between generative nucleus and pollen tube nucleus.
Summary – Generative Nucleus vs Pollen Tube Nucleus
Pollen grain nucleus is divided by mitosis and produce nuclei. Two nuclei are generative nuclei while one is pollen tube nucleus. Generative nuclei are the male nuclei; one fuses with the nucleus of the egg cell to form the zygote while the other nucleus fuses with two polar nuclei to form the endosperm. Pollen tube nucleus guides pollen tube growth within the pistil into the embryo sac. Both, the generative nucleus and pollen tube nucleus are haploid. Thus, this summarizes the difference between generative nucleus and pollen tube nucleus.
Reference:
1. “Flowering Plant Reproduction: Fertilization and Fruits.” Flowering Plant Reproduction II, Available here.
Image Courtesy:
1. “Double Fertilization” – The original uploader was Triploid at English Wikipedia. – Transferred from en.wikipedia to Commons. (CC BY 3.0) via Commons Wikimedia
2. “Pollen-tube-growth-on-germinated-pollen-a-ungerminated-pollen-without-a-pollen-tube-b-400” By Melekber Sulusoglu, Aysun Cavusoglu – Melekber Sulusoglu et. al. "In Vitro Pollen Viability and Pollen Germination in Cherry Laurel ( Prunus laurocerasus L.)", The Scientific World Journal doi:10.1155/2014/657123 (CC BY 4.0) via Commons Wikimedia