Leaves and flower petals come in all shapes and sizes, but how do they know what shape to grow?
The petals of a flower play a major role in attracting pollinators, such as birds and insects. This is why they develop to be such bright colours and eye-catching shapes. Little is known, however, about how petals grow and acquire their features.
A group of biologists and computer scientists from the United Kingdom were keen to find out about the growth patterns of petals. They studied a plant called Arabidopsis, which is a small species commonly used in plant genetics research. The scientists had already done some research into the growth rules of leaves, so they were able to compare and contrast the developmental patterns of narrow, pointy shaped leaves to broad, fanning petals.
The scientists found that while leaves and petals develop in much the same way, their shape is determined by their function. Leaves are organs that harness energy from light through photosynthesis while the function of petals is to catch the eye of pollinators. The group also discovered hidden maps that direct the growth of petals towards the tip of the flower bud. Molecules called PIN proteins were found to play a role in this hidden map and the scientists explain that these proteins are probably what make petals orient themselves into a rounded shape.
“The discovery of these hidden polarity maps was a real surprise and provides a simple explanation for how different shapes can be generated,” said professor Enrico Coen, author of the study published in the PLOS Biology journal, in a statement.
The researchers conclude their paper by suggesting that these hidden maps and plant growth systems must be flexible to allow plants to adapt to their environment, which is one of the reasons why we see different shaped flowers growing in different parts of the world.
Pollinators move pollen from the male part of a flower called the anthers to the female part of the same or another flower called the stigma. They are required in the process of plant fertilisation. Examples of pollinators are bees, bats, butterflies, birds, lizards and even monkeys.