When it comes to reproduction, at first glance it’s easy to believe that plants have it easy when compared with animals. After all, they don’t have to engage in elaborate displays or fights to win over females since most flowering plants are both male and female. However, for the Japanese climbing fern, things aren’t so simple.
Individual plants of this species (Lygodium japonicum) are either male or female, which begs the question: how do they ensure a balanced ratio between the sexes to ensure reproduction can occur in communities? This phenomenon piqued the interest of researchers at Nagoya University and the University of Tokyo, who endeavored to find out the mechanisms behind this interesting process. As described in their newly published study, which can be found in Science, they discovered that these plants communicate with each other using pheromones. These signals actually dictate the sex of maturing individuals and thus ensure the ideal number of each sex in a community.
The key player in this process was found to be a well-known pheromone called gibberellin. This name may ring a bell for some as it was crucial in the Green Revolution after the Second World War. Gibberellin acts as a growth hormone in plants, and back then researchers discovered ways to manipulate sensitivity to it, producing hardier varieties that helped increase crop yields.
The researchers discovered that young gametophytes—a sexual phase that produces gametes—are all female. These structures are equipped with a particular synthetic pathway that produces a precursor to gibberellin, which is secreted into the surrounding environment. This molecule can then be absorbed by neighbors that are in a later developmental stage, where it is modified into active gibberellin which triggers male organ formation. This tends to result in female plants being surrounded by males, which promotes genetic variation within the colony.
According to lead researcher Makoto Matsuoka, these intriguing findings could have important ecological implications. L. japonicum is an invasive species in some areas, so developing a way to target gibberellin could serve as a strategy to help prevent their spread.