April 1, 2015

Precision Breeding Offers Great Benefits

In the beginning, when the very first crops were tended, our hunter-gatherer ancestors laughed and said, “It can’t be done,” and forecast the demise of the farmer as the hunters marched out of camp to kill the beast that would become the tribal meal that night.

Meanwhile, back at the farm, we worked at producing enough to survive, honed our craft and produced a little more each year.  About 12,000 years ago—when the Neolithic Revolution occurred—the hunters settled down with us as we farmers gained the ability to provide for the tribe.  The first 11,800 years of farming progressed slowly.  Plants, techniques, irrigation and infrastructure improved and the day came when we had a surplus, thus beginning the first markets.

Over the last 200 years,  the technological leaps, including the Haber-Bosch process and Norman Borlaug’s HYV’s (high yield varieties), have resulted in an explosive growth in crop yield that has allowed us to produce more food on the same or similar amount of land.  Today, a small fraction of the global population (13 percent) is producing a huge diversity of staple and specialty crops in tropical, arid and arctic areas to feed more than seven billion people.   We have succeeded at a Herculean task, but one which inevitably becomes more difficult every year.

Diseases, pests, climate change, loss of arable land and an exploding population will require further significant innovation in the future.  While many concerns will be dealt with and play a role in the future of farming and food, one thing is certain:  We will need a broad and diverse catalog of improved plant varieties to address the challenges of how to produce enough food in the face of these challenges, if we are to sustain our world.  Where will these new varieties and plants come from?  Modern technology married to traditional breeding programs is yielding a whole new level of precision and efficiency that holds the promise for our future.

Everyone in this industry is aware of the active public controversy about the genetic modification of plants through the insertion of genes (particularly when not from the parent organism).  The shrill and emotional outcry of those who oppose “genetically modified organisms” has eroded marketplace and public perceptions for crops and foods produced using these methods.  While the scientific community has established consensus over the safety of these methods and the resultant crops and foods, consumers maintain their reservations, and as such these are not yet viable tools and technologies for many growers.  We may be able to develop a staple crop that could eliminate Vitamin A deficiency in a population but if people are afraid of it or you can’t sell it, what’s the point?

There are, however, other methods of developing new plants and varieties.  Key among these methods is the introduction of speed and precision into more classic plant breeding programs.  One example is “molecular breeding.”   It can be used to generate the plant variety and traits that are necessary to increase yields, reduce reliance on inputs, combat pests and disease and improve the nutritional and aesthetic properties of crops destined for human consumption by combining traditional practices with emerging knowledge and science.

The field of “molecular breeding” may be one of our strongest tools to help ensure the future of agriculture.  In essence, it combines the knowledge of a plant’s whole genome with classic breeding techniques used by agriculturalists for generations.  It is a method that enhances both speed and precision such that we can identify and target desirable traits within the wholly-mapped genomes of related plants.

In the day of Gregor Mendel, the founder of the science of genetics, getting desirable traits in progeny was uncertain, imprecise and took a great amount of time.  Generation after generation of plant breeding, and a process of informed trial and error, was necessary to get to the desired result.

Today we are moving beyond Mendel.  With precise genetic maps and sequenced genomes, molecular breeders have a clearer line of sight to the specific traits that can be quantitatively associated with specific genes that are either desirable or undesirable.  These genes can be “tagged” using genetic markers uniquely associated with the desired traits.  Then, rather than crossing the parents and growing the progeny out to maturity, breeders can search for these discrete markers or “tags” at the very early seedling stage, thus significantly shortening the breeding program.

A University of California Agriculture and Natural Resources publication (Suslow, Thomas, Bradford) used the following example to illustrate this process:  A tomato variety containing a gene for resistance to root knot nematode was discovered in a wild relative of the tomato and transferred into cultivated tomatoes through traditional breeding (sexual crossing and embryo rescue).  This process was slow, requiring each progeny to be planted into nematode-infested soil and grown to maturity prior to examination for resistance/infection.  Later, breeders discovered a (genetic) “marker” from the wild parent was located on the chromosome next to the (nematode resistant) desired gene and that each time the gene was transferred so was the marker.  This allowed breeders to speed the process dramatically by testing for the marker and predicting the gene would be present.  This is a clear example of how traits that may be hard to come by (e.g.  difficult to pass on or expressed at later stages of a crop), can be selected (or avoided) with a much higher degree of precision much earlier in the breeding process.  With “molecular breeding,” agriculture can benefit from great genetic gain in a fraction of the time and at a much lower cost than traditional breeding. 

Several mainstream environmental organizations that are stridently opposed to the insertion of foreign genes (transgenics) into crops for agronomic traits such as herbicide tolerance or insect resistance, are either accepting or more tolerant of molecular breeding programs.  With this technique, pollen-based breeding programs informed by modern biotech tools bridge the rich history of agriculture’s beginning with new cutting-edge technology.  The broader public acceptance of traditional breeding informed by modern methods and science will surely benefit farmers and consumers and the environment in which we all co-exist. 

As more and more of the commodities important to modern agriculture and the specialty crop sector are genetically mapped and sequenced, and as this information is made more widely and publicly available, I anticipate the speed of genetic gain to accelerate dramatically.  The genetic code is ripe for the next generation of “hackers” who can team up with the trusted hands of plant breeders to ensure the future of food and farming.