Dr. Ravindra Chibbar
Canada Research Chair in Molecular Biology for Crop Quality
For Ravindra Chibbar, crop quality lies with the taste of the consumer. As a major exporter of agricultural products, Canada relies on its researchers to develop crops that satisfy changing consumer tastes for everything from nutrition to mouth feel.
Carbohydrates and proteins, the two major components that determine quality and end use for cereals and pulses, are his main targets.
Consider starch, a major storage carbohydrate in grains. Starch is everpresent in our lives, from toast at breakfast to bowl of noodles at lunch and side dish of potatoes at supper. Even that after-work beer owes its existence to this essential molecule.
Starch is made of thousands of glucose molecules joined together to form water-insoluble granules. Only in wheat, barley, rye and triticale, these granules come in two sizes, A (large) and B (small). Both are composed of amylose, an essentially linear chain, and amylopectin containing highly branched chains of glucose molecules.
Wheat with more than 85 per cent amylopectin can be used to make high quality Japanese udon noodles. The opposite scenario, high amylose wheat, produces bread with less digestible starch, and hence fewer calories absorbed.
Companies that extract gluten from wheat dislike starch with small granules because these are hard to wash away during the gluten extraction process. Brewers, on the other hand, like large-granule barley starch, as they feel it allows more beer from the same amount of grain.
By identifying the genes responsible for starch biosynthesis in cereals, Chibbar and his team have developed markers – genetic tags that can quickly identify desirable traits from varieties around the world. Armed with these tools, crop breeders at the College of Agriculture’s Crop Development Centre can easily choose the candidates most likely to deliver improved quality. This partnership has already yielded an amylosefree waxy wheat, due to arrive in Canadian fields in 2005.
While Chibbar’s specialty is how plants make carbohydrates like starch, some of his work has other applications. He and his colleagues patented a genetic promoter for wheat that promises to be a powerful tool for variety improvement and even molecular farming.
“This promoter is associated with starch deposition in the grain, so one can use it to deposit any desirable product,” he says. “This could be anything–a pharmaceutical, nutritionally beneficial product or coloring agent.”
Chibbar is also part of a major effort funded by Genome Canada to unlock the secrets of frost tolerance in cereals, particularly wheat. For years, plant breeders have been stuck on a cold-tolerance plateau with this crop. Frost-hardy rye, for example, has been crossed with durum wheat to create triticale, but the hybrid succumbs to the cold as easily as its wheat parent.
“The idea is to use molecular biology tools to understand the molecular basis of cold-tolerance” he says. “Once we have these tools, such as molecular markers, and the key genes characterized – then the knowledge can be used by winter wheat breeders to break the cold tolerance plateau.”
A new challenge for Chibbar and his team are pulse crops like lentils and peas. In the past 30 years, Saskatchewan has grown into the dominant world exporter in some of these crops. However, as any schoolchild knows, a diet high in pulses has consequences.
Chibbar intends to harness the same tools that have brought such success in cereals to pulses. The aim is to use marker-assisted breeding to reduce oligosaccharides – the complex sugars that cause digestive upset. Improved varieties may help farmers capitalize on a North American trend.
“People are moving towards having more vegetarian meals, especially in the U.S.,” he says. “Legumes play an important role in providing the protein part of these diets.”