Food security currently sits on the edge of a perilous precipice; a rapidly growing global population and warming climate mean crop yields may soon plummet to unprecedented lows – endangering the lives and livelihoods of millions. With this in mind, researchers around the world have been employing the most cutting-edge biological tools to protect future generations from the famines and economic disasters that would ensue as a result of increased crop damage by climate change.
For decades, researchers have used transgenics to transplant genes from other species into crops, resulting in varieties of rice, barley, maize, and soybean (amongst others) which show increased growth, yield, nutrient content and grain quality under conditions that the changing climate will likely present (increased drought, flooding and extremes of temperature). However, transgenic approaches result in the production of GM (genetically modified) crops. The growth and consumption of which is very controversial, with 39% of US adults stating that they believe GM crops have a negative effect on health, whilst only 24 countries currently allow the cultivation of GM crops. So, despite their successes in the lab, very few of these GM crop varieties make it to the field (and on to our plates) due to poor public perception, and legislature against their growth and consumption in many parts of the world.
CRISPR (clustered regularly interspaced short palindromic repeats) technologies have been the emerging means of quickly and efficiently causing genetic changes in many organisms, for the last decade. CRISPR utilizes the ability of the bacterial Cas9 enzyme to degrade DNA of invading organisms, such as viruses, and the (sometimes error-prone) ability of all organisms to reassemble their own DNA strands when broken. This approach allows supremely accurate genetic changes to be made in many species, and has been used successfully in crop species such as tomato, rapeseed and rice to improve harvest quality and yield, as well as product shelf life. Despite these successes, its use in many crop species is complicated by the size and complexity of their genomes. For example, bread wheat has 3 entire genomes, meaning it has 6 copies of every gene – subsequently, simultaneously causing genetic changes in every copy of the gene, via CRISPR, is a tall order.
Instead of using these cutting-edge molecular biology methods of genetic manipulation, more and more researchers are now turning to ancient tools. Namely, these researchers are aiming to exploit the genetic diversity that exists naturally in ancient varieties of many crop species and integrate novel genetic changes into modern crop varieties via conventional breeding. Ancient crop varieties show massive genetic diversity, compared to their modern-day counterparts, as these varieties have not undergone the dramatic loss of novel genetic markers that comes as a result of modern breeding programs. Instead, ancient varieties have been grown on a small scale, whilst over many decades, farmers select for those plants which are particularly adept at growing in the local climate. These ancient varieties are cultivated in this manner in almost every climate around the world, resulting in a wide array of crop varieties in possession of specialized traits, essential for growth in their local climate; traits encoded by unique combinations of thousands of genetic markers, absent from modern varieties. Because these ancient varieties have adapted to grow in almost every climate around the world, they invariably show tolerance to unfavourable growth conditions, such as low rainfall, high temperature, low temperature or salinity. Therefore, researchers are hoping that using these ancient varieties in breeding programs will ultimately lead to these specialist traits being transferred to more high-yielding, modern varieties. This transfer of novel genetic markers encoding specialist adaptive traits will occur by conventional breeding approaches, meaning that exploiting the natural genetic diversity of ancient varieties to produce improved crops bypasses the various problems (both legislative and scientific) associated with GM and CRISPR crops.
So, unlike transgenic and CRISPR approaches, it seems that breeding using ancient varieties is more likely to produce crop varieties which make it out of the lab, into the field and on to our plates. This begs the question, is it time that more researchers look to ancient varieties as a way of protecting future crop yields against climate change?