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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.
The best studied mechanisms of SI act by inhibiting the germination of pollen on stigmas, or the elongation of the pollen tube in the styles. These mechanisms are based on protein-protein interactions, and the best-understood mechanisms are controlled by a single locus termed S, which has many different alleles in the species population.
If the pollen is compatible it will germinate and begin to grow. [5] The ovary releases chemicals that stimulates a positive chemotropic response from the developing pollen tube. [6] In response the tube develops a defined tip growth area that promotes directional growth and elongation of the pollen tube due to a calcium gradient. [5]
Double-strand breaks in DNA that arise during pollen tube growth appear to be efficiently repaired in the generative cell that carries the male genomic information to be passed on to the next plant generation. [21] However, the vegetative cell that is responsible for tube elongation appears to lack this DNA repair capability. [21]
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During germination, the tube cell elongates into a pollen tube. In the flower, the pollen tube then grows towards the ovule where it discharges the sperm produced in the pollen grain for fertilization. The germinated pollen grain with its two sperm cells is the mature male microgametophyte of these plants. [2]
Actress Danielle Vasinova is opening up about her unique experience with death. In December 2019, months before COVID was declared a pandemic, Vasinova caught the virus. The actress, who will kick ...
The BBC reported that the first-known mince-pie recipe dates back to an 1830s-era English cookbook. By the mid-17th century, people reportedly began associating the small pies with Christmas. At ...