Washington, Sept 23 : Green plants and animals enjoy a relatively close evolutionary relationship than previously thought, a new study by an East California University biologist has revealed.

Plants, fungi and animals are all in a group called the eukaryotes – distinguished by their advanced cellular machinery. But some eukaryotes, most notably the fungi, have long been considered more closely related to animals than plants are.

Now, biologist John Stiller has suggested that organisms such as fungi should be given a demotion placed further from animals on the tree – while green plants should get a leg up.

In a new paper, scheduled for publication in the journal Trends in Plant Science, Stiller has outlined at least five common features in animals and green plants that could not have emerged independently.

“In both green plants and animals, cell cycles are controlled by master switches. These function, and malfunction, similarly in both groups,” he said.

Stiller cited the example of a shared malfunction, whereby both groups suffered from cancerous growths consisting of rapidly diving cells that grew unchecked.

“The difference is that plants can often simply drop the growth in the way that they drop off their leaves, but humans and animals don't possess that ability,” he said.

He said another attribute shared by plants and animals, was the way the genetic material RNA operated in both groups.

In both plants and animals, RNA acts as an intermediary between DNA and the protein it codes for. The enzymes that put RNA to work in a cell are similar in plants and animals, but not present in fungi or other organisms.

Also like animals, plants have an immune system, but for the latter, certain proteins and genes, which are not present in other organisms, help plants and animals defend themselves against invading viruses and bacteria.

Stiller said the most intriguing possibility was the strong parallels between plant neurobiology and animal nervous systems.

“Plants obviously do not have actual nerves and brains, but electrical signals do allow plants to sense and to signal. Some of the proteins involved in this process are the same in both group,” Discovery News quoted Stiller as saying. (With inputs from ANI)