Photo/IllutrationA type of moss in which MADS-box genes has been destroyed grows a longer stem than that with active MADS-box genes. (Provided by the National Institute for Basic Biology)

Scientists have discovered the role of flower-making genes by examining a flowerless moss.

About 20 years ago, MADS-box genes that produce flowers were found in plants without flowers such as moss.

However, how the genes functioned remained a mystery. Until now.

The study team that includes scientists from the National Institute for Basic Biology in Okazaki, Aichi Prefecture, found that the MADS-box genes control the length of plant stems and affect sperm movements in the moss called Physcomitrella patens.

“The discovery will lead to a breakthrough to find how the MADS-box genes became flower-making genes,” said Mitsuyasu Hasebe, a member of the team and professor of plant evolution studies at the institute.

The findings were published in the British scientific journal Nature Plant on Jan. 3.

In the study, when scientists destroyed the MADS-box genes in the Physcomitrella patens, its stem extended about 1.5 times longer than usual.

The elongated stem prevented water from being supplied from the base of the stem to the tip where sperm would swim in water from the antherdium toward the archegonium for fertilization.

The study also showed that some sperm in the plants with destroyed MADS-box genes were also inactive even if they were in water.

Flowering plants are known to have originally evolved from flowerless plants.

The team surmised that in the process of evolution, the flowerless plants decided they no longer needed sperm to swim and fertilize eggs and this resulted in the MADS-box genes having other functions.