The Secrets of Plant Sex: New Breakthrough Concerning Successful Fertilization

When plants have sex, they use pollen to fertilize flowers. Unlike animals, though, plants require not one, but two sperm cells for successful fertilization. Now, researchers have solved the mystery as to why plants need these two sperm cells for sex.

In this case, the researchers discovered a pair of proteins made by flowering plants that are vital for the production of the sperm present within each pollen grain. The pair of genes are called DAZ1 and DAZ2, and are essential for making the twin sperm cells. In fact, plants with mutated versions of these genes produce pollen grains with a single sperm that is unable to fertilize.

DAZ1 and DAZ2 are controlled by the protein DUO1, which acts as a "master switch." Essentially, it causes the genes to work in tandem to control a gene network that ensures that a pair of fertile sperm is made inside each pollen grain.

More interestingly, the scientists found that DAZ1 and DAZ2 perform their role by cooperating with a "repressor" protein known as TOPLESS that acts as a break on unwanted gene activity that would otherwise halt sperm and seed production. While TOPLESS has many roles in plants, previously it had not been linked to sperm production.

"We often take for granted sexual reproduction in plants and its role in our lives," said David Twell, one of the researchers, in a news release. "IT is a complex process that has been studied scientifically for over a century, but it is only recently that we are beginning to get a grip on the underlying mechanisms. We hope to use our discovery to decipher the origins of sexual reproduction and to further demystify the fascinating process-of how plants make the fertile sperm inside the pollen grains-that are essential for the vast majority of our food crop production."

Learning about DAZ1 and DAZ2 could also have practical applications. Their discovery could be applied in the development of new plant breeding techniques in the future.

The findings are published in the journal The Plant Cell.