Date:13 August 2013
A team spanning four institutions and 19 researchers has finally cracked the genetic code behind what people have known for thousands of years: one rotten apple in a barrel spoils all the other apples and an apple ripens a green banana if they are put together in a paper bag.
It’s all to do with ethylene gas. In the online journal eLIFE, a large international group of scientists, led by investigators at the Salk Institute for Biological Studies, has traced the biological trigger activated by ethylene, which is released in the examples given above.
Besides helping to ripen fruit, ethylene regulates growth and helps defend a plant against pathogens.
Isolating the specific genes that perform all of these might allow production of plant strains that slow down growth when needed, accelerate or prevent ripening, retard rotting or make plants more resistant to disease, says senior investigator Joseph Ecker, professor in Salk’s Plant Molecular and Cellular Biology Laboratory.
The brainpower involved academics specialising in a variety of fields, including computer science, computational biology and genomics. The study also represents a milestone for Ecker, who has devoted his career to understanding the power exerted by plant-based ethylene.
“I have been trying, for several decades, to understand how a simple gas – two carbons and four hydrogens – can cause such profound changes in a plant,” Ecker says. “Now we can see that by altering the expression of one protein, ethylene produces cascading waves of gene activation that profoundly alters the biology of the plant.”
In the plant they studied, Arabidopsis thaliana, related to cabbage and mustard, they found that ethylene causes activation of EIN3, a master transcription factor (a protein that controls gene expression). EIN3 and a related protein, EIL1, are required for the response to ethylene gas. They then found that thousands of genes in the plant responded to EIN3, which acted as a sort of master regulator. In addition to providing insight into how ethylene genetically controls diverse functions within a plant, the study also helps decode the workings of other plant hormones – essential to understanding their regulation of growth and development, be it in seed germination, fruit ripening or responding to drought, insects or pathogens, a team member said.
Source: Salk Institute for Biological Studies