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Scientists discover a gene for determining plant sex

Researchers from the University of Tasmania have discovered a gene responsible for determining the sex of a plant, a breakthrough which could provide a boost for agriculture and forestry.

Dr Scott McAdam, Associate Professor Timothy Brodribb and Dr Frances Sussmilch from the School of Biological Sciences have led an international collaboration involving world-leading researchers from Germany’s University of Würzburg and Purdue University, USA, to characterise a fern gene essential for the perception of a sex-determining hormone.

Their findings have been published in one of the world's most-cited and comprehensive multidisciplinary scientific journals, Proceedings of the National Academy of Sciences of the United States of America (PNAS).

The research highlights the extraordinary effect that a plant hormone, which originally evolved to control sex, has had on land plant evolution and ecology over the past 450 million years.

Their study is the culmination of three decades of genetic work with a fern species, coupled with the latest molecular and physiological techniques for gene characterisation, protein function and plant behaviour.

Dr McAdam, an Australian Research Council Discovery Early Career Researcher Award fellow, said the discovery meant scientists now understood how plants become male or female.

“In animals like humans, X and Y chromosomes make a person male or female, but in ferns a hormonal balance in a one-day old plant sets maleness or femaleness and we previously had no idea how,” Dr McAdam said.

“What is really exciting about our discovery is that we now know of a gene that regulates sex by hormone perception and that it has done this for a very long time, at least 370 million years, from when our ancestors were still fish.”

The research shows that through the gene GAIA1, hormones are able to control the sex of plants, and that over time plants have evolved additional uses for this perception pathway.

These uses include the control of seed dormancy (essential for an even germination of crops) and the control of excessive plant water loss (essential for plants growing in dry environments).

“This gene first evolved to control sex, but it was so good at informing the plant about the environment that plants now use it for other things like seed dormancy as well as the restriction of water loss from leaves,” Dr McAdam said.

“This evolutionary change means that this gene is used by every one of our most important crop and forest species to survive during drought or on hot days.

“Last spring and summer Tasmania experienced an extreme drought, and the subsequent fires destroyed huge areas of rainforest. If it wasn’t for this hormone perception gene stopping the remaining plants in these forests from losing all of their water reserves, Tasmania would now be a desert.

“Understanding how these plant processes operate at a genetic level provides the critical first step towards making major improvements to drought tolerance in crop and forest species, or more ideal sex ratios in crops that produce both male and female flowers.”

The full article is available to read online.

Published on: 11 Nov 2016 2:47pm