Breeding Healthier Pulses (PCN Winter 2013) JAN 1 2013 | Consumers and Producers | Pulse Crop News
This article appeared in the Winter 2013 issue of Pulse Crop News.
Higher yield. Better standability. Disease resistance. Traditionally, pulse breeders have focused on breeding better plants to suit the needs of growers. Through classical breeding techniques that involve crossing plants and observing traits, pulse breeders have developed new varieties that have made pulses easier to grow.
Now, with a burgeoning world population to feed, more and more thought is being given to developing pulses that are also healthier to eat. Limited resources, however, mean that pulse breeders must focus primarily on breeding stronger plants, not healthier seeds.
But University of Calgary researcher Dr. Dae-Kyun Ro is not a pulse breeder. Rather, he is one of the growing numbers of scientists who are laying the foundation for breeding crops with health beneficial attributes in mind.
“The history of plant breeding goes back at least 5,000 years, but our understanding of healthier crops is only very recent,” said Dr. Ro, who has a Ph.D. in the field of plant biochemistry from the University of British Columbia. “For a long time, we just did not understand the healthy components present in pulses and other plants.”
This knowledge gap has had far-reaching impacts on the work done in traditional breeding programs, according to Dr. Ro. “Breeding goals have often not been based on healthy diet but based on some other characteristics that do not directly improve our health and wellness. Thanks to the new knowledge in nutrition and plant metabolism, now we know what compounds are good for health and how these compounds are synthesized in plants.”
To that end, researchers at the University of Alberta and the University of Calgary set out to explore the health beneficial attributes of pulse crops – specifically tannins, which are known to have antioxidant and anti-carcinogenic properties. As part of this project, Dr. Ro and his team looked at a portion of the pea genome to better understand tannin biosynthesis in an effort to identify the molecular mechanism controlling the tannin synthesis in pea. By understanding the mechanism, researchers can devise methods to control the quality of tannins in pea and other pulse crops either through breeding or other molecular techniques, according to Dr. Ro.
“Studies of the genome provide a comprehensive snapshot of gene activation when tannins are being actively produced,” said Dr. Ro. “Classical experiments study one or two genes at a time, but using new genomics approaches, we can investigate thousands of genes simultaneously. We anticipated that hidden genetic components could be revealed by employing an unbiased genomics approach.”
To test this theory, Dr. Ro’s project team chose five pea cultivars, a mix of both tannin and low-tannin varieties. The team then used next-generation DNA sequencing technology and obtained more than a million sequencing reads from the different cultivars. Using a computer to analyze this data, the team compared the activation of genes in tannin-rich cultivars against low-tannin cultivars, which allowed them to link the tannin profiles with the activated parts of the pea genome.
The team found that the tannins synthesized in pea are both longer and have a higher degree of hydroxylation than the tannin identified in other crops – two traits that are related to higher levels of antioxidant activities. The team then set out to answer which genetic components in pea dictate the type, quantity, and length of tannins in different cultivars.
Using the genomics data, Dr. Ro’s team found that some low-tannin pea cultivars have mutations in the master molecular switch of tannin metabolism. His team also identified one novel genetic component that is potentially related to the tannin length. As a result of this discovery, Dr. Ro’s team is exploring the possibility of modulating tannin length.
Each of these findings can be applied to breeding pulses that have greater health attributes, according to Dr. Ro. “In all living organisms, the genome serves as a blueprint. The information for desirable traits is all coded in pulse genomes, and we can utilize genomic data to develop healthier pulse crops. For example, if we want to have a pea plant containing specific type of tannin, we can use the gene and genomic information to select specific pea lines. You can use the same principle for all useful traits.”
While classical breeding has allowed breeders to chase certain desirable traits through crossing and trait observation, breeding can be accelerated and done more predictably when accurate genome information is available because breeders will know exactly the absence or presence of certain genetic variations that are associated with physiological traits.
“Understanding the molecular mechanisms, or genes, involved in tannin synthesis in pea will give plant breeders new tools to help develop new pulse crops with nutritional value in mind in addition to the conventional target traits,” said Dr. Ro. Having the genomic information can also facilitate more rapid breeding programs, leading to the development of new crops in a shorter period of time, and possibly give Alberta farmers an advantage.
But in order to realize this advantage, organizations like Alberta Pulse Growers must continue to invest in projects that support basic scientific discovery as well as projects with immediate application in the field.
“My research is placed at the boundary of basic and applied science,” said Dr. Ro. “A lack of basic science today will not negatively influence the Alberta economy in the next five or perhaps 10 years; however, our next generation will not be competitive enough if we do not invest time and funds in basic research now.”
Dr. Ro explained that sequencing the whole pea genome is essentially a basic science project that will not influence the pea industry immediately – but the long-term benefits are already evident. “Sequence-based plant breeding is a leading-edge technology in all developed countries. It is obvious that the pea genome will play critical roles in pea breeding in the next decades.”
While agronomic traits – including increased yield, disease resistance, and lodging resistance – will continue to be a priority for Alberta pulse breeders, Dr. Ro feels that support must also be given to projects where the pay-off may not be immediate if Canada hopes to maintain a competitive agricultural industry.