Safeguarding chickpeas from significant changes in climate

Chickpeas! The key component of hummus, an excellent addition to soups, a key source of protein, iron, and other delightful minerals.

Cara Jeffrey is a PhD candidate with the School of Life and Environmental Sciences, and her research project is focusing on understanding mechanisms of heat tolerance in chickpeas, with a focus on genetic mapping. This research hopes to set a baseline for breeders to produce heat tolerant types of chickpeas, safeguarding a staple food in many countries.

A lot of people in Australia don’t realise just how important an agricultural product chickpea is. The average annual gross production value for the last 5 years is AU$699.6 million, and in 2017 we were the third-largest chickpea trader worldwide. It’s easy to understand how this isn’t common knowledge though, as most of what we produce is exported, and it’s pretty small-scale when compared to crops like wheat.

It’s not news to anyone that we’re currently experiencing the effects of climate change. According to a study done by CSIRO in 2013, the global climate departure year is 2069 ± 18, if emissions are stabilised, and 2047 ± 14 if not. That means that by the year 2069, the global temperature will be consistently higher than the historical norms. 

All organisms exist within a specific temperature range, meaning that they need a specific set of temperatures to survive comfortably, as cells require specific temperatures to function. Plants don’t have the same capacity to thermoregulate as animals, they cannot ameliorate this stress, and so it becomes terminal much faster. This means that as our climate warms, the global agriculture industry is at risk of losing production, and potentially failing completely as plants fail to thrive.

Chickpeas are pretty tough plants. Their evolutionary progenitor is from Syria and Egypt, and they’re pretty happy living off light rains and stored soil moisture. But when chickpeas were domesticated for human use, they moved to milder climates, and now they get uncomfortable at roughly the same temperature as we do (above 30 degrees Celsius).

In order to safeguard this crop from significant changes in climate, we have to focus on a few sources of tolerance, one of which is heat. Essentially, we have to toughen them up, and get them to a point where they can tolerate higher temperatures. Which is where Cara's research comes in.

Currently, we know that there are some cultivars of chickpea that are more tolerant to high temperatures, meaning they maintain a similar yield at higher temperatures compared to ambient, but we’re not entirely sure why or how. If we knew what the mechanisms were that gave heat tolerance, we could use that knowledge to inform future breeding efforts, thus allowing farmers access to heat-tolerant cultivars to grow, safeguarding their income.

Modern selective breeding uses things called Molecular Markers, which are essentially fragments of DNA that can allow us to map a genome. A genome is the culmination of all of your DNA, and it can be mapped. So, while people tell us that DNA is the blueprint of life, it’s more like the genome is the blueprint, and the DNA is the house itself. You can have genomes of entire species too, not just individuals. Kind of like a plan for a housing development.

Cara's PhD seeks to take notes on how plants behave in terms of physiology and biochemistry, match these characteristics with high yield under heat stress, and then match data with the species genome. By doing this, we can understand what region of the genome codes for each characteristic, and then understand what genes control for high yield under heat stress.

An example of this may be that plants with more heat tolerant pollen have a higher number of fertilised flowers. More fertilised flowers means more pods, which means more seeds, which means a higher yield. If we know that cultivars X, Y, and Z all have high yields and resilient pollen, we can have a look at their DNA and figure out which piece they have in common. This piece potentially codes for resilient pollen, and we can then target it for future breeding, which would create more tolerant cultivars.