Fatty acid composition and genome-wide associations of a chickpea (Cicer arietinum L.) diversity panel for biofortification efforts

Authors: SALARIA, SONIA - Clemson University; BOATWRIGHT, LUCAS - Clemson University; JOHNSON, NATHAN - Clemson University; JOSHI, PRIYANKA - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; THAVARAJAH, PUSHPARAJAH - Clemson University; Vandemark, George; THAVARAJAH, DIL - Clemson University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2023
Publication Date: 8/27/2023
Citation: Salaria, S., Boatwright, L., Johnson, N., Joshi, P., Thavarajah, P., Vandemark, G.J., Thavarajah, D. 2023. Fatty acid composition and genome-wide associations of a chickpea (Cicer arietinum L.) diversity panel for biofortification efforts. Scientific Reports. 13:14002.

Interpretive Summary: Fatty acids have several important metabolic functions in the human body, including storage of energy sources for use under reduced blood glucose levels, regulating gene expression, forming cell structures, promoting cell signaling, and helping control cholesterol levels and inflammation. Fatty acids are classified into saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). In general, increased consumption of saturated fatty acids tends to be associated with adverse health effects. Palmitic acid is a SFA that has been associated with disorders of the circulatory, digestive and nervous systems. Conversely, oleic acid is a MUFA that has anti-inflammatory properties, and linoleic acid and alpha-linolenic acid are PUFAs associated with improved cardiovascular health. In 2021, chickpea was the second most important pulse crop in terms of global production after dry bean. Although chickpea breeding programs focus on yield enhancement and disease resistance, greater efforts have been made recently to also improve nutritional qualities. With respect to fatty acid profiles, our breeding objectives are to develop improved chickpea cultivars that have higher concentrations of the unsaturated fatty acids oleic acid, linoleic acid, and alpha-linolenic acid, and lower concentration of the saturated fatty acid palmitic acid. To make improvements through plant breeding, we first must identify parental chickpea lines that have desirable fatty acid profiles. We may be able to accelerate breeding progress by identifying genetic markers that are associated with desirable fatty acid profiles. Consequently, the objectives of this study were: 1. Evaluate a panel of diverse chickpea materials for seed concentrations of palmitic acid, oleic acid, linoleic acid, and alpha-linolenic acid, and 2. Identify genetic markers associated with fatty acid concentrations and candidate genes that may regulate fatty acid concentrations. A wide concentration range was observed for palmitic acid (450.7–912.6 mg/100 g), linoleic acid (1605.7–3459.9 mg/100 g), alpha-linolenic acid (416.4–864.5 mg/100 g), and oleic acid (1035.5–1907.2 mg/100 g). These values correspond to the following percent recommended daily allowances for palmitic acid (3.3–6.8%), linoleic acid (21.4–46.1%), alpha-linolenic acid (34.7–72%), and oleic acid (4.3–7.9%). We also identified 38 DNA markers that were associated with concentrations of palmitic acid. This is the first reported study to characterize fatty acid profiles across a chickpea diversity panel and detect genetic markers associated with fatty acid concentrations. These findings suggest we can use conventional breeding approaches and genetic markers to develop superior chickpea cultivars with more nutritional fatty acid profiles.

Technical Abstract: Chickpea is a nutritionally dense pulse crop with high levels of protein, carbohydrates and micronutrients, and low levels of fats. Chickpea fatty acids are associated with a reduced risk of obesity, blood cholesterol, and cardiovascular diseases in humans. We measured four primary chickpea fatty acids; palmitic acid (PA), linoleic acid (LA), alpha-linolenic acid (ALA), and oleic acid (OA),which are crucial for human health and plant stress responses, in a chickpea diversity panel with 256 accessions (kabuli and desi types). Wide concentration ranges were found for PA (450.7–912.6 mg/100 g), LA (1605.7–3459.9 mg/100 g), ALA (416.4–864.5 mg/100 g), and OA (1035.5–1907.2 mg/100 g). The percent recommended daily allowances also varied for PA (3.3–6.8%), LA (21.4–46.1%), ALA (34.7–72%), and OA (4.3–7.9%). Genome-wide association studies (GWAS) were conducted using genotyping-by-sequencing data. A total of 38 significant single nucleotide polymorphisms (SNPs) were identified for PA. Admixture population structure analysis revealed seven subpopulations in this panel based on ancestral diversity. This is the first reported study to characterize fatty acid profiles across a chickpea diversity panel and perform GWAS to detect associations between genetic markers and concentrations of selected fatty acids. These findings demonstrate biofortification of chickpea fatty acids is possible using conventional and genomic breeding techniques, with the aim of developing superior cultivars with better fatty acid profiles for improved human health and plant stress responses.