AgResearch team finds missing link

10 May 2012

AgResearch team finds missing link

AgResearch scientists have made a breakthrough proving a long-held hypothesis that white clover originated as a hybrid of other clover ancestors, followed by a chance doubling of the chromosome number to restore fertility.

This opens the way for breeding and management that unlocks benefits for farmers and pastures. AgResearch is already actively using the new information in breeding programmes to produce improved clovers for New Zealand.

The findings have just been published in the journal BMC Plant Biology. This will share the work with researchers and scientists around the world. White clover (Trifolium repens) is widespread and has become the most important legume in grazed pastures worldwide.

Evidence from AgResearch studies using DNA sequence analyses, chromosome staining, interspecific hybridisation and breeding experiments supported the hypothesis that a diploid alpine species (T. pallescens) hybridised with a diploid coastal species (T. occidentale) to generate allotetraploid T. repens.

The coming together of these two narrowly adapted species (one alpine and the other maritime) thousands of years ago, led to the hybrid clovers we know today It is suggested that during the Ice a=Age T. pallescens was forced to retreat to low altitude coastal refuges of Portugal and Spain and similar sites where species T. occidentale currently occurs. An inter-species hybridisation event between these two plants with very narrow but different adaptations produced the broadly adapted white clover that rapidly established throughout Europe following the retreat of the glacial advances.

“These findings immediately create new opportunities for clover improvement by extending the genetic resource base because it facilitates the development of 'synthetic white clovers' from the now defined ancestors,” said Dr Warren Williams who led the research.

“The benefits of this are important and exciting as this opens the way to select traits using breeding to increase traits that could benefit pasture persistence, animal nutrition and pest resistance,” said Dr Williams.

“Finding the missing link between white clover and the plants that hybridised to create it allows us to reincorporate ancestral genes and this has significant possibilities as the world looks to a growing population.”

The successful team comprised Warren Williams of AgResearch who is also a Professorial Fellow in Plant Breeding, College of Sciences, Massey University, and Nick Ellison, Helal Ansari, Isabelle Verry and Wajid Hussain all from AgResearch’s Grasslands Campus.

ENDS

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