McGill professor increases yields in soybean crops by up to 25%

A new technology and a new company are born

Infants allergic to cow’s milk owe their very life to soybeans. Most people appreciate its pasta, oil and condiment versions. And a good proportion of the planet’s livestock feed on it. It is not surprising then, that even in the northern areas of North America 25.5 million acres of land are dedicated to the production of soybean. "And this in spite of the fact that in these areas soybean is a long way from home," says Professor Don Smith, of the McGill Department of Plant Science, one of the world’s experts in soybean production. "The wild ancestor of this plant evolved in the tropics and, as a result, soybean doesn’t like the cold. One of its most attractive agricultural features also doesn’t like the cold. Soybean doesn’t require nitrogen fertilizer -- the most expensive of the major nutrients in fertilizers -- because it forms a relationship with Bradyrhizobium, a soil bacterium which allows the soybean plant to use the largely inert nitrogen which makes up 80% of the air we breathe as food while the soybean in return allows bacteria to feed on the sugar in its tissue."

Because these beneficial bacteria actually enter the roots of legumes the plants must take care to let in the useful bacteria and not accidentally let in any which cause root diseases. In order to make sure the bacteria are the correct ones, the plants produces signals which are sensed by the Bradyrhizobium, causing them to swim toward the root. At the same time these signals activate a set of bacterial genes which are otherwise off. These genes play a critical role in the development of root outgrowths (nodules) where the bacteria eventually reside while they are fixing nitrogen. The first thing they do is produce signals which the bacteria send to the plant, turning on the plant genes necessary for nodule development.

These genes are very specfic, with only those produced by the bacteria appropriate to the legume sending the correct signals. It is a fascinating exhange in that the bacteria and the plant regulate each other’s genomes before they even come into contact with each other. The whole system acts like a clever password exchange, says Professor Smith. "The correct question must be asked, and the correct answer must be returned." Not only that but it turns out that the soil must be at the right temperature.

Dr. Smith and his students have recently discovered that low soil temperatures, typical of those occurring during the early growing season in most northern soybean production regions, disrupt the signal exchange process, so that there is a long delay before the beneficial soil bacteria can enter the soybean roots and begin to fix nitrogen. Dr. Smith has found that when they are under stress, and cool soil temperature (below 25 degrees Celsius) is a definite stress, neither the bacteria nor the soybean roots will send out sufficient levels of signals. That means soybeans germinating in cool soil have to struggle on their own to pick up enough nitrogen to grow. Generally, the result of that struggle is noticeable in the form of pale leaves and slow growth. Dr. Smith and his team were able to show that below 25 degrees Celsius, for each degree dropped it took 2 days longer for nitrogen fixation to start. Below 17 degrees Celsius, it gets worse requiring 7 to 10 days per degree.

Dr. Smith also wanted to know whether the entire nodulation process was equally low- temperature sensitive or whether certain steps were particularly temperature-resistant. "When we tested for that it turned out that the first 12 hours following the exposure of the root to the bacteria were crucial. So we looked at the signal exchange process which is known to show during these twelve hours; a procedure which took us no less than 10 years in the field and in the lab. We discovered that the plant roots then had trouble manufacturing their signal below 25 degrees Celsius and that this was true for the bacteria as well. So we developed a technique where we can overcome the problem. "Normally, when a farmer plants a soybean crop he or she will also add an inoculant containing the beneficial bacteria to the seeds just before they go into the ground. But, the further below 25 degrees Celsius the temperature is at planting, the slower things will happen. Soil temperatures at planting in Canada are generally around 10 degrees Celsius at planting time. This is why Dr. Smith and his team decided to add signal molecules into the inoculant that is added to the soil planted with soybean seeds. And they found that the cultivars tested with their solution increased the speed of nodulation formation and began to fix nitrogen 4 to 5 days sooner. This is an important difference as nitrogen fixation by soybean growing in Canada tends to finish in mid-August, when the seeds are forming in the pods. This means that the total time available for nitrogen fixation is short, and even a few days can make a large difference. "In the end," remarked Dr. Smith, "the total amount of nitrogen fixed during the season was increased by 40 to 70% and the resulting increase in crop yield was as high as 25%. Results from laboratory experiments showed that signal molecules worked at low soil temperatures and now we have been able to show that they also work in the field."

Through a chance encounter Dr. Smith became aware of InnoCentre, a non profit organization designed to help establish high tech companies based on recent research developments in university laboratories. The notion of the company was born under the stewardship of InnoCentre. The incubation of NorAg Inc. on the Macdonald Campus of McGill University was made possible through the combined efforts of Dr. Bernard Robaire, Associate Vice-Principal Research, who made a strong commitment to the effort, and the McGill Office of Technology Transfer (OTT).

However, the company needed someone to manage it. In this sense the advent of the company was timely. Just as Dr. Smith’s research funds were beginning to decline, the result of the significant cuts in government support for research during the last few years, the company presented new opportunities for personnel in Dr. Smith’s laboratory, and Stewart Leibovitch, the former laboratory manager, moved over and began to manage the company. More recently NorAg has begun to take off and both Stewart Leibovitch and Dr. Smith realized that the complexity of the business dealings and the level of business type of activity was getting beyond their very scientific expertise. In order to deal with this Pierre Migner, a former graduate student of Dr. Smith’s who has worked in industry since leaving McGill, has come into NorAg to manage the business side of things and become the companies new president.

The focus of NorAg is to develop and market microorganism-based seed treatments designed to improve crop yield and quality for agronomically important crop species. The federal government has registered for sale this spring an innoculant containing the 532 - C strain of of Bradyrhizobium (developed by Dr. David Hume at the University of Guelph) treated with the new biological triggers developed by Dr. Smith at the Macdonald Campus of McGill University.