Taro (Colocasia esculenta (L.) Schott) is a tropical tuber crop whose underground corms are used as an important staple food. However, due to a lack of molecular markers, the genetic diversity, germplasm identification, and molecular breeding of taro are greatly limited. In this study, high-density InDel-SSR molecular markers covering the whole genome were developed based on the resequencing data of taro core germplasm. A total of 1,805,634 InDel-SSR loci were identified, and 219 highly polymorphic markers with an average polymorphism information content PIC value of 0.428 were screened. Furthermore, a genetic diversity analysis of 121 taro germplasm resources was conducted based on 219 markers, dividing the resources into three groups. In addition, an association analysis showed that, of the multiple InDel-SSR markers, g13.52 and g12.82 were significantly associated with leaf area and average cormel weight, respectively; the candidate genes CeARF17 (EVM0014444) and CeGA20ox (EVM0001890) were related to cormel expansion; and we excavated the candidate genes CeXXT2 (EVM0016820) and CeLOG1 (EVM0017064), which regulate leaf development. The InDel-SSRs and candidate genes identified in this study are expected to provide important support for genetically improving and breeding new varieties of taro.

Taro is a tuber crop that is used for nutritional and medicinal purposes due to its abundance of non-starch polysaccharides (NSPs). Red Sprout taro is a local variety in Southern China, but the characteristics and bioactivities of its NSPs are currently unknown. In this study, NSPs were isolated from the corms of Red Sprout taro using hot-water extraction, ion-exchange chromatography, and ethanol precipitation; their molecular weight, monosaccharide composition, structural formulae, and immunomodulatory effects were examined. A novel NSP named Colocasia esculenta polysaccharide 1 (CEP1) was purified and characterized and was shown to mainly consist of glucose (60.49%) and galactose (25.92%) and have a molecular weight of 4556.272 kDa. The backbone of CEP1 consisted primarily of →4)-α-D-Glcp-(1→, →4,6)-β-D-Galp-(1→, and →3)-β-D-Galp-(1→ residues, with a branch consisting of the β-D-Glcp-(1→ residue. In addition, 25–400 µg/mL CEP1 was shown to have immunomodulatory effects on RAW264.7 macrophages. CEP1 not only increased cell viability, phagocytic capacity, inducible nitric oxide synthase secretion, and nitric oxide generation in RAW264.7 cells, but it also activated M1 and M2 macrophages to generate tumor necrosis factor α, interleukin 6, transforming growth factor β, and interleukin 10. These findings could lead to the use of CEP1 from Red Sprout taro as a possible immunomodulatory polysaccharide in functional foods.

The greater yam (Dioscorea alata L.) is a major food crop in tropical and subtropical regions, particularly in Africa. However, anthracnose disease, caused by Colletotrichum spp., significantly threatens greater yam production. Identifying anthracnose-resistant greater yam varieties is therefore of great importance. In this study, we evaluated the anthracnose resistance of 46 greater yam varieties using in vitro leaf inoculation with C. alatae isolated and identified at Jiangxi Agricultural University (Nanchang, China). We examined the physiological and biochemical indices, including stomatal density and opening, activities of peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL), as well as abscisic acid (ABA) levels, in leaves of varieties with different resistance levels. Compared with susceptible varieties, immune and resistant varieties exhibited lower stomatal density and higher leaf wax content. Following infection, immune and resistant varieties rapidly increased POD and PAL activities, along with the expression of their encoding genes. Stomata in immune and resistant varieties closed, whereas those in susceptible varieties opened, facilitating pathogen invasion and resulting in rapid growth and accumulation of anthracnose mycelia in susceptible varieties. Resistant varieties maintained higher leaf ABA levels than the susceptible varieties during the early stages of inoculation. Additionally, the exogenous application of ABA enhanced the resistance of susceptible varieties. Our findings suggest that resistant greater yam varieties may improve resistance by increasing endogenous ABA levels and inducing stomatal closure, thereby hindering the invasion of anthracnose pathogenic mycelia. These results provide important insights for breeding anthracnose-resistant greater yam varieties and developing sustainable disease management strategies.