Fruit and Seed Metabolomic Profiles Provide Insights into the Utilization of Sour Jujube Germplasm

To fully evaluate sour jujube germplasm ( Ziziphus spinosa ) at Las Cruces, NM, and western Texas, we sampled sour jujube trees both in Las Cruces, NM, and Fabens/Tornillo, TX, to examine their fruit and seed metabolomic profiles to facilitate further exploration of those sour jujube germplasm resources. Mature fruit samples were harvested from Las Cruces, NM, and Tornillo/Fabens, TX, with sour jujube and middle types (crosses between wild ones and jujube cultivars) plus two jujube cultivars. Jujube germplasm fruit metabolomic profile reveals that cultivar samples were related to sour jujube germplasm samples from Texas. Based on acquired metabolite profiles, sour jujube samples in New Mexico were separated from sour jujube samples in Texas. Sour jujubes and crosses in Texas exhibited overlapping profiles. Therefore, the Texas cross group was eliminated, and sour jujube germplasm was separated by location New Mexico vs Texas. The Texas samples had significantly higher contents of many metabolites of amino acids and derivatives. More compounds were identified from seed samples, and the grouping/principal component analysis results were similar to fruit metabolomic results. New Mexico sample trees were planted around 1959/60, which could be from one nursery, closely related to each other. The Texas germplasm was the result of human selections, not the original sour jujubes but hybrids between sour jujubes or sour jujube and cultivar-like germplasm. Jujubogenin was rich in both fruit and seed samples for selected terpenoids. The dominant triterpenes were different between fruit and seeds. The TX2 seed sample was extremely high in several flavonoids—anthocyanidin B3, B1, and B2; pelargonidin-3- O -rutinoside; isoquercitrin; and nicotiflorin—20 to 90 times higher than the average of New Mexico samples. With its foot-long decorative branchlets and high flavonoid content in seeds, TX2 has the potential to be used as an edible landscape plant and for nutraceutical or pharmacological uses. The heat map data of 1687 metabolites in fruit and 1985 metabolites in seeds would be good references for future utilization of those jujube germplasm plants for horticultural or pharmaceutical purposes.