A new transport route for volatile plant compounds

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A new transport route for volatile plant compounds

Purdue researchers discover new transportation route for plant volatile compounds

Flowers use volatile compounds called terpenes to communicate with and protect themselves from the outside world. They also allow the plant to protect itself from pests and diseases.
Petunias use terpenes to communicate

Now, a study by Purdue University shows that petunias use terpenes as part of a kind of internal communication and to improve their reproductive abilities. Natalia Dudareva, a professor in Purdue's biochemistry department, published the results in an article in Nature Chemical Biology.
A petunia bud that has not opened (top) will aerially transfer volatile compounds from the tube of the flower to the stigma before opening. The discovery, by Purdue University scientists, is the first organ-to-organ communication detected in flower. (Purdue Agricultural Communication photo/Tom Campbell)
"In general, volatile compounds help communication and defense from one plant to another, but this is the first time we have seen that plants use these compounds for communication and signalling between organs," Dudareva said. "It's practically a new physiological process that we've never seen before."

Dudareva, with her co-authors showed that before the opening of a petunia flower, she acted as a kind of fumigation chamber. "We were looking for the presence of terpenes in the reproductive organs of petunia flowers and found that these compounds accumulated in the stigmatization.

But gene expression and activity leading to the biosynthesis of these terpenes did not occur in the stigma. It was happening in the flower tube," said Boachon.
Three experiments to confirm their hypothesis

The researchers conducted three experiments to confirm their fumigation hypothesis that the terpenes present in the stigma were actually generated and emitted by the flower tube and then transported by air and absorbed by the stigma.

First, they grew the flower bud without the tube and noted that there was much less accumulation of terpenes in the stigma. Then they added a label to the compounds in the flower tube. Further analysis showed that the labelled compounds were found in the stigma.

Finally, they have silenced the gene that produces terpenes in the flower tube. The resulting flowers had less accumulation of terpenes in their stigmas. Terpene accumulation could be restored in the stigmas with the silenced gene by simply placing them in tubes containing the active gene.

Surprisingly, the petunias without fumigation of the terpenes of the flower tube also produced smaller stigmas and about 30% fewer seeds. This suggests that controlling terpene production in plants could increase seed production, which was not considered before this work.
Terpenes act as hormones
"We had believed that these volatile compounds were involved in defense and communication, but not in the development process," said Dudareva. "We now see that they have functions similar to hormones. It may be possible to improve the development of the reproductive organs and increase the number of seeds. This opens up a new field for the study of a physiological process involving these compounds. "