*4.5. Carotenoids*

Several studies have reported a carotenoid profile in pulse crops [183,185,186,201–204] (Table 1). Lutein, zeaxanthin, and β-cryptoxanthin were reported in chickpeas [183,202], whereas violaxanthin, lutein, and β-carotene were reported in field peas [201,203]. Thavarajah and Thavarajah [184] reported a high concentration of carotenoids, beta-carotene (166–431 μg/100 g), canthoxanthine (21–68 mg/100 g), and xanthophyll (9–20 mg/100 g) in 10 chickpea genotypes grown in Minot, North Dakota.

Ashokkumar et al. [185] evaluated carotenoids profile in 12 pea and 8 chickpea cultivars grown at multiple locations in Saskatchewan, Canada, using high performance liquid chromatography with a diode array detector. This method is sensitive, reliable, and accurate for the separation and quantification of putative carotenoids. In peas, the concentration of carotenoids was greatest in cotyledon, followed by embryo axis and seed coat. Green cotyledon cultivars (16–21 μg g<sup>−</sup>1) had generally higher concentrations compared to yellow cotyledon cultivars (7–12 μg g<sup>−</sup>1). Lutein was the major component (11.45 μg g<sup>−</sup>1) followed by violaxanthin (0.52 μg g<sup>−</sup>1), β-carotene (0.47 μg g<sup>−</sup>1), and zeaxanthin (0.16 μg g<sup>−</sup>1). In kabuli type chickpea cultivars, carotenoid concentration was highest in the cotyledon, followed by the embryo axis and seed coat, whereas in the desi type, the seed coat, followed

by the cotyledon and embryo axis, had the highest carotenoid concentration. Lutein (7.70 μg g<sup>−</sup>1) was the major component followed by zeaxanthin (5.76 μg g<sup>−</sup>1), β-carotene (0.40 μg g<sup>−</sup>1), and violaxanthin (0.05 μg g<sup>−</sup>1).

In subsequent work, Ashokkumar et al. [186] observed a wide range of variation in concentration of carotenoids in genetically diverse pea (94) and chickpea (121) accessions grown at multiple locations in Saskatchewan, Canada. In the peas, the concentration of lutein was highest (11.2 μg g<sup>−</sup>1) followed by β-carotene (0.5 μg g<sup>−</sup>1), zeaxanthin (0.3 μg g<sup>−</sup>1), and violaxanthin (0.3 μg g<sup>−</sup>1), whereas in the chickpeas, the concentration of lutein (8.2 μg g<sup>−</sup>1) was highest followed by zeaxanthin (6.2 μg g<sup>−</sup>1), b-carotene (0.5 μg g<sup>−</sup>1), β -cryptoxanthin (0.1 μg g<sup>−</sup>1), and violaxanthin (0.1 μg g<sup>−</sup>1). Green cotyledon peas and desi chickpeas had a greater carotenoid concentration than yellow cotyledon peas and kabuli chickpeas, respectively. Pea and chickpea accessions with high carotenoid concentration that can be utilized in future breeding were identified. In five chickpea cultivars with different cotyledon colors, total carotenoid concentration varied from 22 μg g<sup>−</sup><sup>1</sup> (yellow cotyledon kabuli) to 44 μg g<sup>−</sup><sup>1</sup> (green cotyledon desi), with lutein and zeaxanthin as major components [187]. In a recent study, a wide range of total carotenoid concentration was observed in three F2 populations developed by crossing cultivars with different cotyledon and seed coat colors, CDC Jade X CDC Frontier (14.9–58.1 μg g<sup>−</sup>1), CDC Cory X CDC Jade (1.9–77.6 μg g<sup>−</sup>1), and ICC4475 X CDC Jade (21.6–83.7 μg g<sup>−</sup>1) [188].

Total carotenoids (5.8–26.9 μg g<sup>−</sup>1) and β-carotene (2.6 μg g<sup>−</sup>1) were greater in peas [186] compared with potato accessions (1.4–14.3 μg g<sup>−</sup>1) [205] and golden rice endosperm (1.6 μg g<sup>−</sup>1) [206]. Similarly, in 121 chickpea accessions, the concentration of total carotenoids (15.0 μg g<sup>−</sup>1) was three times greater than in 42 banana accessions (4.7 μg g<sup>−</sup>1) [207] and 37 potato accessions (4.4 μg g<sup>−</sup>1) [208]. Of all carotenoids identified, lutein was the major compound in chickpeas [183,185,186,202] and peas [185,186,201,203,204]. Further, lutein has positive correlations with chlorophyll concentration in peas [203] and zeaxanthin concentration in chickpeas [183].

Previously, four QTLs for beta-carotene concentration and a single QTL for lutein concentration were detected in chickpeas [183] (Table 1). Using a GWAS, Rezaei et al. [187] identified 32 candidate genes involved in isoprenoid and carotenoid pathways across all eight chromosomes of chickpeas. They observed positive correlation between the expression of genes of carotenoid biosynthesis with various carotenoid components. In a subsequent study, several QTLs were identified for total carotenoids and individual components in three F2 populations, CDC Jade × CDC Frontier (8 QTLs on LGs 1, 5, and 8), CDC Cory × CDC Jade (5 QTLs on LG 8), and ICC4475 × CDC Jade (5 QTLs on LGs 3 and 8) [188]. Further, several candidate genes associated with carotenoid components were observed with a major gene for cotyledon color on LG 8 in each population.
