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Traditional plant breeders improve the quality and yield of crops by crossing plants with desired traits to create a new, hopefully improved, hybrid strain. But traditional breeding is limited by the available gene pool of a cultivated plant species and eventually hits a wall--reshuffling the same genetic variation can boost yield only so much. With the advent of biotechnology, plant scientists were buoyed by the prospect of improving plants through genetic modification. But aside from a few successes with introducing single-gene herbicide- and pest-resistant traits, most plant traits have proved too complex to repay the incorporation of a single transgene--that is, a gene taken from a different species--with the hoped-for response. Biotech-based investigations and applications in plant science have also been hampered by consumer reaction against genetically modified organisms.
Faced with these limitations, Amit Gur and Dani Zamir of The Hebrew University of Jerusalem tried another approach--a back-to-nature approach. "Natural biodiversity is an unexploited sustainable resource that can enrich the genetic basis of cultivated plants," they explain in the report.
First Gur and Zamir identified genomic regions in wild tomato species that affect yield, by creating a population of hybrid crosses of a wild tomato species and a cultivated tomato species; each line had a single genomic region from the wild tomato inserted into the cultivated plant. They then combined three independent yield enhancing genomic regions from the wild species into the new plant line. Plants were grown over three seasons, during which they were exposed to different environments, including drought. By combining traditional breeding techniques with genetic marker analysis, the authors identified a number of wild tomato genomic regions that dramatically increased yield.
Their results demonstrate that an approach based on biodiversity--which takes advantage of the rich genetic variation inherent in wild relatives of cultivated crops--can produce varieties that outperform a commercially available hybrid tomato in both yield and drought resistance. Gur and Zamir attribute the improved performance to their unique breeding strategy. Their hybrid model--applying the tools of modern genomics to traditional plant breeding--offers plant breeders a powerful approach to improving the quality and yield of cultivated plants by taking advantage of the inherent biodiversity of the natural world. It's a strategy that may well apply to rice, wheat, and other vital staples of the world's food supply.
Citation: Gur A, Zamir D. (2004) Unused Natural Variation Can Lift Yield Barriers in Plant Breeding. PLoS Biol 2 (10): e245.
CONTACT:
Dani Zamir
The Hebrew University of Jerusalem
Hertzel Rehovot, Israel
+972-8-948-9092
+972-8-948-9943 (fax)
zamir@agri.huji.ac.il
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