Take home message

• International trends suggest a potential shift towards composition traits such as protein content as market targets in chickpea
• In-depth characterisation of proteins in chickpeas, with a focus on Australian varieties provides a valuable tool for future market shifts.
  • Variable grain protein concentration in existing germplasm
  • Protein has been linked to regions of the genome
  • Potential to breed for high protein
• Understanding the effect of agronomic and environmental influences on chickpea seed composition will support effective management for grain quality in future markets.
  • Environmental conditions have a significant impact on grain protein
  • Potential to use agronomic interventions for protein content
• We have developed a chickpea toolkit to prepare for potential changes in market demand.

Background

Global demand for sustainable protein sources is increasing, and as a result there has been significant interest in plant-based sources of protein ingredients. Pulses have presented a key area of interest given their generally high protein content (when compared to cereal grains) and the established use of soybean as a source of plant-based protein ingredients. Globally, this has led to the development of protein ingredient markets dependent on pulse grains, such as the large emerging field pea protein market in North America (Canada’s domestic pea protein consumption averaged 420,000 tonnes from 2018/19 – 2022/23 (Saskatchewan Pulse Growers, 2025)). Chickpeas and chickpea proteins are generally considered to have good functional properties in foods (Grasso et al., 2022). As such there is the potential to grow chickpea demand beyond established markets into emerging plant-based protein ingredient markets.

Chickpeas are traditionally valued by physical attributes such as size and colour, the investigation of the differences in composition is relatively limited. As such, an understanding of the genetic variation in chickpea varieties, or breeding targets that would be most valuable for potential protein market are poorly understood. Characterising the composition of diverse chickpea germplasm including landraces, varieties and breeding lines is considered a first step towards providing tools to breeders and growers in the event of shifts in market demand.

The value of chickpeas on the international market is highly variable and is impacted significantly by market forces from India, such as recent tariffs. The establishment of an Australian protein industry could assist in market stabilisation of grain prices, while also delivering a high-quality product for the export market.

Methods

A chickpea diversity panel (240 different varieties) was established using grain sourced from the ICRISAT gene bank and supplemented with commercially available elite Australian cultivars. Lines were grown under common glasshouse conditions and grain was harvested.

Grain was then analysed for protein, soluble sugar, starch, lipid and fibre content. Protein was measured by Bradford assay, soluble sugars were extracted in ethanol and measured by anthrone, starch was measured by enzymatic assay, and fibre in the remaining pellet was measured gravimetrically (Pritchard et al.,2011). Lipids were extracted in chloroform:methanol, dried down, and weighed.

This information was used to perform genome wide association studies (GWAS). This was done in collaboration with the University of Tasmania using the GAPIT package in R.

The proteome of eight Australian cultivars of chickpea was also investigated. Proteome analysis involves measuring and counting the amount and type of all the proteins present at measurable concentrations in the seed. The proteome of these lines was extracted in alkaline water, trypsin digested and analysed though LC-MS/MS for identification and quantification (Bose et al., 2024).

Interesting lines from the diversity panel characterisation were further investigated in different environmental conditions in glasshouse settings. One of these experiments involved growing eight chickpea lines (selected for varying protein content and lipid content) under two different nitrogen conditions – high nitrogen, watered with a complete nutrient solution weekly, and low nitrogen, watered with a nitrogen free solution weekly. The plants were grown to maturity, the grain was harvested and analysed as above.

Results and discussion

Chickpea grain composition and genome wide association studies (GWAS)

Characterisation of the grain composition of the chickpea diversity panel revealed large ranges in composition for all measured traits (Figure 1); with ranges as follows: Protein (9.5-27% w/w), starch (22.3-41.8% w/w), soluble sugar (1.9-7.8% w/w), insoluble fibre (10.3-25.3% w/w) and lipid (6.2-10.9% w/w).  Further, this variation was observed in both Kabuli and Desi type chickpeas, with both market classes having similar ranges of composition for all measured traits. This is a particularly promising result, as it suggests that lines with potentially valuable composition traits, such as high protein, could be developed in both market classes. The large variation across all composition traits when grown under common conditions suggests a genetic influence. Because of this we performed a GWAS to identify the regions of the genome associated with traits of interest; this yielded 11 regions significantly associated (significant association threshold = 4.6) with grain protein content. These 11 regions were spread across five of the eight chromosomes of chickpea. These associations present an opportunity to develop markers to assist with and speed up breeding. Validation of these regions as markers could support chickpea breeders in generating high protein chickpea lines more quickly if faced with a change in market demand.

Figure 1. Macromolecule composition of chickpea seeds from a 240 line diversity panel.

Chickpea protein composition

Eight Australian chickpea cultivars were selected for further investigation. This involved measuring and counting the amount and type of all the proteins present in the chickpea seed at measurable concentrations (proteomics). The most abundant kind of proteins found in the seed, as expected, were storage proteins. These proteins can be characterised into different groups depending on their solubility in different solvents. These groups also indicate some difference in the functionality that these proteins will have in food. Legumins were found to be the most abundant storage protein in chickpeas (Figure 2) and globulins were the least abundant. While the relative ratios of abundance across lines were relatively consistent (with some variation in the relative abundance of albumin and vicilin) the concentration of protein differed significantly between lines within protein classes. For more details see Bose et al.,2024.

Figure 2. Composition of the main storage proteins in the chickpea proteome from eight Australian grown chickpea cultivars.

This holds potential for food applications as these different protein classes can perform different roles in food mixtures. Albumins for example are soluble in water. They also form foams well and can act as egg replacements, while globulins form firm gels when heated

(Grasso et al., 2022). Understanding the different protein profiles of the chickpeas grown in Australia will help to differentiate Australian chickpea products globally and target them to specific market segments.

Chickpea protein under environmental variation

We are also conducting experiments to better understand the effect of environment on chickpea composition. Given the impact of soil nitrogen on grain protein in other, non-legume species, soil nitrogen composition was one of the first traits we measured. As legumes are able to source atmospheric nitrogen through a symbiosis with rhizobia in their roots, they are not solely dependent on soil nitrogen. Chickpeas, however, did show significantly higher concentrations of protein in their grain when grown under high nitrogen conditions (Figure 3). This was true for all varieties tested.

Figure 3. Chickpea grain protein composition of 7 lines grown on high nitrogen (HN) and low nitrogen (LN) soils. *** denotes statistical significance. ns = not significant

These investigations of chickpea grain grown under different environmental conditions, and the subsequent scaling of these experiments to the field will give a more complete image of the factors affecting chickpea grain composition. This in turn can be used to inform agronomic practices that will produce grain suited to specific market demands. In the event of a strong shift towards a protein-based market for chickpeas in the future, this could help growers maintain high value crops until varieties with genetically determined high protein content are available.

Conclusions

Key findings

Chickpea grain composition is highly variable, meaning it is amenable to selection of, and breeding of, lines with specific composition characteristics. There is also notable composition diversity in lines already grown in Australia, suggesting that there is the potential to develop lines with desirable grain characteristics adapted to Australian environments. Further, the impact of the environment on grain composition suggests that there may be scope to develop agronomic interventions to achieve desired grain composition profiles.

Overall, this groundwork demonstrates Australian cultivars have diversity which would leave growers well placed to pursue markets driven by grain composition. Further research and breeding efforts should support and complement efforts in meeting potential demands in emerging markets, supporting the industry to take advantage of opportunities as they appear.

Ongoing research

Investigation of the impact of nitrogen fertiliser in field conditions is currently under analysis. Commercially available varieties were grown in the same paddock under 4 different soil Nitrogen regimes in the last field season. These samples will also be processed to give insight into how they perform in food applications.

Ongoing projects are also investigating the impact of terminal drought and heatwaves on grain composition and grain protein composition.

The proteome across the development of the grain is also being investigated to understand the timing of different developmental processes in grain filling and the potential impacts of stress at different stages of grain development.

Future prospects

Further field studies of both the performance of genetics and the impacts that different environmental factors have on grain composition will assist in the validation of genetic associations as markers that can be used for genetic assisted breeding. Having a reliable set of well characterized genetic markers will be an invaluable tool for a rapid shift to a quality defined market for chickpea and other pulse grains.

References

Bose U, Buck S, Sirault X, Bahmani M, Byrne K, Stockwell S, McWilliam S, Colgrave M, Juhasz A, Ral JP (2024) Chickpea Proteome Analysis Reveals Genotype-Dependent Variations Associated with Seed Traits. Journal of Agricultural and Food Chemistry. 72, 27030–27042.

Grasso N, Lynch NL, Arendt EK, O’Mahony JA (2022) Chickpea protein ingredients: A review of composition, functionality, and applications. Comprehensive reviews in food science and food safety. 21(1): 435-452.

Pritchard JR, Lawrence GJ, Larroque O, Li Z, Laidlaw HKC, Morell MK, Rahman S (2011) A survey of β‐glucan and arabinoxylan content in wheat. Journal of the Science of Food and Agriculture. 91(7): 1298-1303.

Saskatchewan Pulse Growers (accessed Jan 2025)

Acknowledgements

S. Buck is supported by a CSIRO Early Research Career Fellowship.
The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

Contact details

Sally Buck
CSIRO
sally.buck@csiro.au

Date published
March 2025

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