Controlling the noxious weed wild radish could save the Australian grains industry $140 million annually.
Family planning for wild radish
New research into the increasingly herbicide-tolerant wild radish (Raphanus raphanistrum) has revealed increased potential for two ‘contraceptive’ approaches to controlling the noxious weed.
“Wild radish is part of a group of plants with a genetic system that prevents them from making seed from their own pollen,” says Professor Andrew Young from CSIRO Plant Industry.
“By tricking the radishes into believing that all pollen is their own we aim to prevent them from making any seed at all.”
What has been crucial to the project is the variability of the genes (S genes) controlling the pollen rejection reaction.
“New research has shown that, although there are many millions of wild radish plants infesting wheat fields across Australia, together they contain less than 30 different S genes,” says Professor Ed Newbigin from the University of Melbourne. “This means that this ‘chemical condom’ approach could be very effective.”
The second approach to reducing wild radish seed-set targets the role of an important plant hormone, gibberellin, which is essential both for plant growth and seed-set.
“Wild radish is part of a group of plants with a genetic system that prevents them from making seed from their own pollen,”
says Professor Andrew Young from CSIRO Plant Industry.
Professor Young says molecular analysis of a key enzyme required for gibberellin production is being used to identify hormone mimics that can selectively target hormone production and seed-set in wild radish without affecting crops such as wheat.
“The gibberellin approach aims to prevent wild radish from making the plant equivalents of sperm and eggs – thus blocking weed reproduction,” Professor Young says. “It’s like a vasectomy for plants.”
A team of scientists from the University of Melbourne and CSIRO has been collaborating on the project over the last three years as part of the CRC for Australian Weed Management.
“Traditional herbicides target plant growth, but this research has taken a different approach in developing novel control strategies based on reproductive interference, which could eventually save the Australian grains industry an estimated $140 million a year,” says Dr Rachel McFadyen, CEO of the CRC.
The team’s current priorities include building realistic computer simulation models of wild radish populations to predict the effects of applying the reproductive subterfuge to the unsuspecting radishes.
“Hopefully, if we can trick enough plants, we will see real reductions in seed-set and the wild radish weed problem,” Professor Young says.
“Our approach is very bad news for wild radish, but it could be very good for the environment and, unlike current herbicides, won’t have any negative effects on wheat – which doesn’t have the same pollen recognition system. We see it as a win-win technology,” he says.
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