Plant breeder joins hunt for heat-tolerance chickpeas

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Holding a wild relative of chickpea (Cicer echinospermum) is University of Sydney postdoctoral research fellow Dr Angela Pattison, who is investigating if these tiny seeds contain the necessary genes to develop new chickpea varieties with superior tolerance to heat stress.

PHOTO: Nicole Baxter

A researcher at the University of Sydney is searching for genes to help make Australian chickpeas more tolerant to heat for improved yield reliability

Dr Angela Pattison, a postdoctoral research fellow at the University of Sydney, has started the intensive work required to hunt for chickpeas with tolerance to high temperatures. The plant breeder, based at Narrabri in northern New South Wales, says high temperatures during the reproductive and post-reproductive phases are a major cause of yield loss in chickpeas.

For example, research in India has demonstrated that the yield of chickpeas declines by up to 301 kilograms per hectare for every 1°C increase in mean seasonal temperature.

Associate Professor Daniel Tan, also from the University of Sydney, says the timing and duration of flowering has an important role in determining grain yield, which is reduced under hot conditions.

“The factors that affect chickpea yield at temperatures higher than 30°C during reproductive development are flower abortion due to pollen sterility, poor pollination, reduced stigma receptivity and pod abortion,” he says.

Working with Dr Kristy Hobson, who leads the GRDC-supported Pulse Breeding Australia chickpea breeding program at the NSW Department of Primary Industries in Tamworth, Dr Pattison plans to use a range of methods to screen chickpeas for heat tolerance.

Her work, as part of the Legumes for Sustainable Agriculture research hub (an investment of the Australian Research Council and the GRDC), uses delayed sowing to establish chickpeas in late July or early August when heat stress is likely to affect flowering and grain-fill.

Chickpeas that are sown later and yield well under hot temperatures will be further assessed to determine which traits can be targeted for genetic improvement.

Dr Pattison will look at the root system of higher-yielding chickpeas to see if they are better able to tap into subsoil moisture than poorer-yielding chickpeas.

Another line of inquiry is to look at anther and pollen development (processes critical to successful pod-set) of high-yielding chickpeas to check if they are more viable in hot conditions.

A third area to be explored is the time of flowering and pod-set to determine if high-yielding heat-tolerant lines flower and fill their pods earlier to avoid hot conditions.

To assist with her research, Dr Pattison is using portable perspex heat chambers (measuring two by two metres) that use air conditioners to control day and night temperatures.

“We plan to stress our chickpea lines for up to a month to find out how we need to apply a heat stress event to identify plants more tolerant to high temperatures,” she says.

“Anther and pollen development will also be tested in our glasshouse facilities to check its viability at different temperatures.”

Delivering traits to industry

After heat-tolerant chickpea lines have been identified, Dr Pattison says there are several ways to deliver the heat-tolerance traits to growers.

“One method uses a straight natural cross where we take a modern chickpea variety and cross that with a line with improved heat tolerance. The offspring of that cross are then tested and the best-yielding lines with heat tolerance are identified,” she says.

“The other option is to make a ‘top cross’ where two chickpea lines exhibiting heat tolerance are crossed to provide two chances of passing on heat tolerance genes to the offspring, before the offspring is then crossed with a modern chickpea variety.”

Another approach Dr Pattison uses to find the genes responsible for conferring heat tolerance is a mapping population.

“You take two chickpeas that are identical in every other trait except heat tolerance, known as near isogenic lines, and cross them,” she says.

“The aim is to make sure there are 100 to 400 offspring, which will have variable levels of heat tolerance. We then scan the genomes of the different chickpeas to look for genetic differences.”

Among the chickpea lines under investigation as part of Dr Pattison’s research are wild relatives of chickpeas, including Cicer echinospermum, imported from Turkey, and others from Syria.

These wild relatives will be crossed with commercially available chickpea lines in the hope of developing offspring with superior tolerance to heat stress.

Drone data collection

Another aspect of Dr Pattison’s research involves exploring the use of drone technology as a tool to collect data for her chickpea pre-breeding program.

With more than 2000 research plots at Narrabri’s managed environment facility, Dr Pattison says the task of measuring biomass production is time-consuming.

“One person is employed for four to five hours to walk beside each plot lugging heavy machinery to collect plant biomass imagery,” she says.

“Flying a drone across the plots would enable biomass images to be collected in just three minutes and provide a snapshot of plant growth in time.”

One of the benefits of drone technology, according to Dr Pattison, is that it enables the researchers to look at canopy temperature (thermal data) and gain a picture of which plants are photosynthesising and which plants have their stomata (small pores in leaves) open.

“By flying the drone across a trial at different times during the day we can quickly see which plant are able to access soil water without having to test root systems or their biomass,” she says. “We hope it will hasten our identification of chickpeas that can better tolerate hot conditions.”

GRDC Research Code US00083

More information:

Dr Angela Pattison,
02 6799 2253,
angela.pattison@sydney.edu.au