Scientist solve 'plant sex mystery'
Two pollen grains viewed by fluorescence microscopy
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Thursday, 23, Oct 2008 07:45
Scientist claim to have solved the mystery of how plant pollen grains can produce 'twin' sperm cells.
In a report published in the journal Nature today, experts from the University of Leicester and POSTECH, in South Korea, looked at the enigma, unique to flowering plants, of 'double fertilisation'.
Flowering plants, unlike animals require not one, but two sperm cells for successful fertilisation. One cell is used to join with the egg cell to produce the embryo, and the other to join with a second cell in the ovary to produce the endosperm, a nutrient-rich tissue, inside the seed.
Now Professor David Twell, of the Department of Biology at the University of Leicester and Professor Hong Gil Nam of POSTECH claim to have discovered a gene that plays a critical role in allowing precursor reproductive cells to divide to form twin sperm cells.
Professor Twell from the University of Leicester said: "This collaborative project has produced results that unlock a key element in a botanical puzzle."
The important gene, known as FBL17, is required to trigger the destruction of another protein that inhibits cell division.
"The FBL17 gene therefore acts as a switch within the young pollen grain to trigger precursor cells to divide into twin sperm cells," the authors claim.
"Plants with a mutated version of this gene produce pollen grains with a single sperm cell instead of the pair of sperm that are required for successful double fertilization," Prof Twell added.
"Interestingly, the process employed by plants to control sperm cell reproduction was found to make use of an ancient mechanism found in yeast and in animals, involving the selective destruction of inhibitor proteins that otherwise block the path to cell division.
"Removal of these blocks promotes the production of a twin sperm cell cargo in each pollen grain and thus ensures successful reproduction in flowering plants."
Researchers claim the new knowledge will be useful in understanding the evolutionary origins of flowering plant reproduction and may be used by plant breeders to control crossing behaviour in crop plants.