Genetic Diversity of Soybeans (Glycine max (L.) Merr.) with Black Seed Coats and Green Cotyledons in Korean Germplasm

Soybeans (Glycine max (L.) Merr.) with black seed coats and green cotyledons are rich in anthocyanins and chlorophylls known as functional nutrients, antioxidants and compounds with anticarcinogenic properties. Understanding the genetic diversity of germplasm is important to determine effective strategies for improving the economic traits of these soybeans. We aimed to analyze the genetic diversity of 470 soybean accessions by 6K single nucleotide polymorphic loci to determine genetic architecture of the soybeans with black seed coats and green cotyledons. We found soybeans with black seed coats and green cotyledons showed narrow genetic variability in South Korea. The genotypic frequency of the d1d2 and psbM variants for green cotyledon indicated that soybean collections from Korea were intermingled with soybean accessions from Japan and China. Regarding the chlorophyll content, the nuclear gene variant pair d1d2 produced significantly higher chlorophyll a content than that of chloroplast genome psbM variants. Among the soybean accessions in this study, flower color plays an important role in the anthocyanin composition of seed coats. We provide 36 accessions as a core collection representing 99.5% of the genetic diversity from the total accessions used in this study to show potential as useful breeding materials for cultivars with black seed coats and green cotyledons.

Breeding of Black Soybean with Green Cotyledon and Four Recessive Alleles for Lipoxygenase, Kunitz Trypsin Inhibitor, Lectin, and Stachyose

Anthocyanins from the black soybean seed coat are known to have many pharmaceutical effects. However, black soybean seed contains antinutritional factors such as lipoxygenase, Kunitz trypsin inhibitor (KTI), lectin, and stachyose. The genetic removal of these components will improve the nutritional value of black soybean seed. The objective of this research was to breed a soybean strain with the black seed coat color, green cotyledon color, and tetra recessive allele (lox1lox2lox3/lox1lox2lox3-ti/ti-le/le-rs2/rs2) for lipoxygenase, KTI, lectin, and stachyose components. Eight parents were used to breed the tetra null strain. Analysis of lipoxygenase, KTI, lectin, and stachyose components in mature seeds was conducted by SDS-PAGE, Western blot, and HPLC. The soybean line with the black seed coat color, the green cotyledon color, a large seed size, and tetra recessive alleles has purple flowers, a determinate growth habit, and brown pods at maturity. The stem height of the breeding line was 52.3 cm. The 100-seed weight of the breeding line was 35.2 g and the yield (Ton/ha) was 2.50. The stachyose content of the breeding line was 3.30 g/kg. This is the first soybean strain with the black seed coat color, the green cotyledon color, a large seed size, and tetra null alleles (lox1lox2lox3/lox1lox2lox3-ti/ti-le/le-rs2/rs2, low content of stachyose, free of lipoxygenase, KTI, and lectin proteins).

Functional Dissection of the Chickpea (Cicer arietinum L.) Stay-Green Phenotype Associated with Molecular Variation at an Ortholog of Mendel’s I Gene for Cotyledon Color: Implications for Crop Production and Carotenoid Biofortification

“Stay-green” crop phenotypes have been shown to impact drought tolerance and nutritional content of several crops. We aimed to genetically describe and functionally dissect the particular stay-green phenomenon found in chickpeas with a green cotyledon color of mature dry seed and investigate its potential use for improvement of chickpea environmental adaptations and nutritional value. We examined 40 stay-green accessions and a set of 29 BC2F4-5 stay-green introgression lines using a stay-green donor parent ICC 16340 and two Indian elite cultivars (KAK2, JGK1) as recurrent parents. Genetic studies of segregating populations indicated that the green cotyledon trait is controlled by a single recessive gene that is invariantly associated with the delayed degreening (extended chlorophyll retention). We found that the chickpea ortholog of Mendel’s I locus of garden pea, encoding a SGR protein as very likely to underlie the persistently green cotyledon color phenotype of chickpea. Further sequence characterization of this chickpea ortholog CaStGR1 (CaStGR1, for carietinum stay-green gene 1) revealed the presence of five different molecular variants (alleles), each of which is likely a loss-of-function of the chickpea protein (CaStGR1) involved in chlorophyll catabolism. We tested the wild type and green cotyledon lines for components of adaptations to dry environments and traits linked to agronomic performance in different experimental systems and different levels of water availability. We found that the plant processes linked to disrupted CaStGR1 gene did not functionality affect transpiration efficiency or water usage. Photosynthetic pigments in grains, including provitaminogenic carotenoids important for human nutrition, were 2–3-fold higher in the stay-green type. Agronomic performance did not appear to be correlated with the presence/absence of the stay-green allele. We conclude that allelic variation in chickpea CaStGR1 does not compromise traits linked to environmental adaptation and agronomic performance, and is a promising genetic technology for biofortification of provitaminogenic carotenoids in chickpea.

AAC Olive marrowfat pea

AAC Olive is a semi-leafless, green cotyledon, and high-yielding marrowfat pea (Pisum sativum L.) variety developed at the Lacombe Research and Development Centre, Agriculture and Agri-Food Canada. It has a maturity of 102 d, average thousand-seed weight of 344 g, and is resistant to powdery mildew (caused by Erysiphe pisi). AAC Olive was certificated on 16 Apr. 2019 by the Canadian Seed Growers Association under the authority of the Canada Seeds Act. The certificate number is 2165-2019.

AAC Comfort field pea

AAC Comfort is a high-yielding, semi-leafless, green cotyledon field pea (Pisum sativum L.) cultivar developed at the Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, in Lacombe, AB. It is adapted to all field pea growing regions in western Canada. AAC Comfort has late maturity, medium lodging resistance, medium seed size, round seed shape, and good bleach resistance and green colour intensity. It is resistant to powdery mildew caused by Erysiphe pisi DC., moderately susceptible to mycosphaerella blight caused by Mycosphaerella pinodes (Berk. & Blox.) Vestergr., and susceptible to fusarium wilt caused by Fusarium oxysporum f. pisi (Linford) Snyd. & Hans.