AN ARABIDOPSIS ANOMALY IN NONSENSE MEDIATED RNA DECAYAN ARABIDOPSIS ANOMALY IN NONSENSE MEDIATED RNA DECAY

23rd Oct 2013

Scientists have misunderstood one of the most fundamental processes in the life of plants because they have been looking at the wrong flower, according to University of Leeds researchers.

Arabidopsis thaliana has become the dominant model plant in genetics research because of its simple genetics and ease of use in a research environment,  but it turns out they may actually contain a rather oddball plant.

A study by researchers at the University of Leeds found that Arabidopsis thaliana was exceptional in not having a key “censorship” protein, involved in Nonsense Mediated mRNA Decay (NMD), called SMG1. SMG1 was known to play a vital role in the growth of animals as multicellular organisms, but scientists thought that plants built their complex life fundamentally differently. That conclusion, it turns out, was built on a dummy sold by Arabidopsis thaliana.

Professor Brendan Davies from the University of Leeds’ School of Biology, who led the study, said: “Everybody thought that this protein was only in animals. They thought that because, basically, most of the world studies one plant: Arabidopsis thaliana.”

Scientists know that this “censorship” process NMD is used by both plants and animals, but thought the two types of organism did it in different ways. Because Arabidopsis thaliana does not have SMG1, which plays a key role in triggering the censorship system in animals, scientists had concluded that SMG1 was not present in any plant.

However, the Leeds researchers discovered that the plant that has established itself as the standard reference plant for all of biology is in fact an anomaly.

“We have found that SMG1 is in every plant for which we have the genome apart from Arabidopsis and we have established that it is being used in NMD. Rather than being just in animals, we are suggesting that the last common ancestor of animals and plants had SMG1,” Professor Davies said.

The study also found SMG1 in Arabidopsis lyrata, a close relative of Arabidopsis thaliana, which suggests that the missing protein has been lost relatively recently in evolutionary time, perhaps in the last 5-10 million years. The next key question for researchers is to explain how organisms without SMG1, such has funghi and Arabidopsis thaliana, work without the protein.

As for Arabidopsis thaliana, it may not have met its Waterloo just yet. “It is still a fantastically useful model. We would not be anywhere close to where we are in understanding plant biology without it, but this is a lesson to us all about the dangers of extrapolating from a single model, however successful that model has been, and the importance of studying processes in a range of models. Evolution does strange and unpredictable things,” Professor Davies said.

The paper, published in The Plant Journal, was co-authored by Professor Davies and University of Leeds PhD student James Lloyd. The research was funded by a grant from the Gatsby Charitable Foundation.

The full paper: James P. B. Lloyd, Brendan Davies, ‘SMG1 is an ancient nonsense-mediated mRNA decay effector’ The Plant Journal (2013) is available to download (DOI 10.1111/tpj.12329)

This article is an abbreviated version of a University of Leeds press release found at: http://www.leeds.ac.uk/news/article/3448/plant_scientists_have_been_studying_wrong_plant