New research will make it quicker and easier for plant breeders to continue developing Australian faba bean varieties with desirable traits.

During a six-month project supported by GRDC, a team of researchers from Agriculture Victoria developed a faster, simplified method of analysing batches of faba germplasm using high-throughput mass spectroscopy.

They wanted to be able to rapidly assess faba bean germplasm for two naturally occurring compounds, vicine and convicine. Often collectively labelled as VC, they are known as anti-nutritional compounds.

High levels of protein and carbohydrates in faba beans make them an important source of food in many North African, Mediterranean and Asian countries, which are major markets for Australian-grown beans.

But up to 30 per cent of people in those regions have a genetic defect that can cause a condition known as favism, making them seriously ill from eating faba beans with high levels of VC.

VC also affect the nutritional quality and bioavailability of nutrients.

Breeding low-VC faba beans

The concentration of the two compounds can be reduced by soaking and cooking the beans, but Agriculture Victoria crop quality group research leader Dr Joe Panozzo says it is still desirable to produce new varieties with very low concentrations.

Dr Panozzo says Australian faba beans have inherently low VC levels, but ongoing testing is essential as more-diverse germplasm is developed to increase yields and maintain resistance to plant diseases.

“Most of Australia’s faba beans are grown in South Australia and Victoria, where it’s an important part of the rotation system,” he says.

“Depending on the market, it can be a high-value product. Traditionally, faba beans were exported and sold for human consumption. More recently, faba beans have been used as a source to extract out the protein and produce protein isolates, which are used as plant-based proteins for food, but not all VC is removed in processing.

“So there’s going to be an increased demand for faba beans both as a source for extracting the protein and for export to the traditional markets, and it’s important for both that the VC concentration remains very low.”

Dr Panozzo says the research started as a scoping study, to see whether it was possible to develop a high-throughput, low-cost screening method to measure VC.

“We ended up with a positive outcome,” he says. “Not all projects can be developed this quickly and often projects that require the development of a method take much longer.”

Previous testing methods were complex, time-consuming and required numerous steps, using hazardous acids and solvents to extract and purify the compounds.

These methods were too expensive to use for early stage screening, which meant testing for VC was often delayed until just before a variety was ready for commercial release, or not carried out at all.

This was not ideal because of the high cost of developing germplasm and the risk of higher-than-acceptable VC levels reaching advanced stages of the breeding program.

Agriculture Victoria crop quality group research leader Dr Joe Panozzo in a faba bean crop. Photo: Joe Panozzo

In contrast, Dr Panozzo says the new method developed by the research team, which included Dr Simone Rochfort, Dr Aaron Elkins and Dr Pankaj Maharjan, has more than halved the analysis time.

“The new method is faster and cheaper due to the reduction in labour preparing samples and reduced volume of reagents,” he says.

“Our aim when we started formulating how we develop this method was, ‘can we use reagents that are more user and environmentally friendly?’ We wanted to move away from organic chemicals and use relatively safe buffers.”

The new method was fully validated using reference standards and crosschecked with previously published data.

The research was published in the September edition of the journal Molecules.

Using the new method, VC extract solutions are stable for longer periods, allowing for batch processing and overnight analysis.

The testing has been shown to be able to detect VC levels across a wide range, and is sensitive down to as little as 0.01 milligrams per gram of convicine.

Dr Panozzo, who has a background in biochemistry, has been measuring the composition of cereals, pulses and oilseeds and quality traits for almost 40 years.

In 2021, he led a GRDC-invested project (DAV1607-006BLX) applying image analysis to quantify a host of quality traits in pulses, such as seed size, colour and protein.

That work formed the basis of this research, which also investigated genetic variation within current commercial faba bean varieties and advanced breeding lines, and the impact of environmental conditions on seed quality traits.

Environment conditions after flowering and during pod-filling alter the (VC) concentration, but it’s still within the low levels.

In collaboration with the GRDC-supported national faba bean breeding program based at the University of Adelaide (UOA1606-009RTX) and Southern Pulse Agronomy (SPA), which provided access to samples, the team studied seven faba bean cultivars – PBA Amberley , PBA Bendoc , PBA Farah , PBA Marne , PBA Nasma , PBA Samira and PBA Zahra – and germplasm of five newer varieties close to release.

Dr Panozzo says testing of harvested seed confirmed medium to low concentrations of VC within the seven commercial varieties and ultra-low VC levels in more recently developed germplasm.

“We found that environment conditions after flowering and during pod-filling do alter the concentration, but it’s still within the low levels,” Dr Panozzo says.

“Often, due to the environment, particularly where the seed is developing under physiologically stressful conditions, such as low soil moisture or high temperatures, the concentration does vary. These factors may become more prevalent with increased climate variability and as faba beans are grown further north.”

The propensity of faba beans to produce flowers over an extended period can result in pod-filling occurring in late spring when higher temperatures are common.

The researchers have recommended further investigation of physiology and agronomy and the impact on faba bean quality traits such as protein, carbohydrates and vicine-convicine.

Now the method has been published, Dr Panozzo says he is hopeful it will be adopted by breeding programs and other researchers.