Euryale ferox, a prominent superfood: Nutritional, pharmaceutical, and its economical importance.

Euryale ferox (also known as foxnut), belongs to the family Nymphaeaceae. It is mainly grown in India, China, Japan, and Korea. It is a highly nutritious food, abundant in nutritional and bioactive compounds such as carbohydrates, protein, fiber, vitamins, minerals, and polyphenols. It is considered a functional food owing to its various health benefits such as antidiabetic, antihyperlipidemic, antifatigue, hepatoprotective, cardioprotective, antimelanogenic, etc. E. ferox has immense potential in both food and non-food industries. Regardless of being recognized as a superfood packed with nutritional as well as medicinal properties, it is still neglected, and there has not been much attention given to its cultivation. Therefore, in this review, the potential of E. ferox as a superfood has been explored to enhance its utilization in the development of different foods and make it available outside its growing area. PRACTICAL APPLICATIONS: Euryale ferox is abundant in several macronutrients and micronutrients; and considered as a superfood in terms of various health benefits. E. ferox has the ability to be used in the development of different health, functional, and nutraceutical foods, which will open a new door for the food industry to combat with numerous diseases.

The adaptive evolution of Euryale ferox to the aquatic environment through paleo-hexaploidization.

Occupation of living space is one of the main driving forces of adaptive evolution, especially for aquatic plants whose leaves float on the water surface and thus have limited living space. Euryale ferox, from the angiosperm basal family Nymphaeaceae, develops large, rapidly expanding leaves to compete for space on the water surface. Microscopic observation found that the cell proliferation of leaves is almost completed underwater, while the cell expansion occurs rapidly after they grow above water. To explore the mechanism underlying the specific development of leaves, we performed sequences assembly and analyzed the genome and transcriptome dynamics of E. ferox. Through reconstruction of the three sub-genomes generated from the paleo-hexaploidization event in E. ferox, we revealed that one sub-genome was phylogenetically closer to Victoria cruziana, which also exhibits gigantic floating leaves. Further analysis revealed that while all three sub-genomes promoted the evolution of the specific leaf development in E. ferox, the genes from the sub-genome closer to V. cruziana contributed more to this adaptive evolution. Moreover, we found that genes involved in cell proliferation and expansion, photosynthesis, and energy transportation were over-retained and showed strong expression association with the leaf development stages, such as the expression divergence of SWEET orthologs as energy uploaders and unloaders in the sink and source leaf organs of E. ferox. These findings provide novel insights into the genome evolution through polyploidization, as well as the adaptive evolution regarding the leaf development accomplished through biased gene retention and expression sub-functionalization of multi-copy genes in E. ferox.

Metabolomics and transcriptome analysis of the biosynthesis mechanism of flavonoids in the seeds of Euryale ferox Salisb at different developmental stages.

Flavonoids belong to polyphenolic compounds, which are widely distributed in plants and have rich functions. Euryale ferox Salisb is an important medicinal and edible homologous plant, and flavonoids are its main functional substances. However, the biosynthesis mechanism of flavonoids in E. ferox is still poorly understood. To explore the dynamic changes of flavonoid biosynthesis during the development of E. ferox seeds, the targeted flavonoid metabolome was determined. A total of 129 kinds of flavonoid metabolites were characterized in the seeds of E. ferox, including 11 flavanones, 8 dihydroflavanols, 16 flavanols, 29 flavones, 3 isoflavones, 12 anthocyanins, 29 flavonols, 6 flavonoid carbonosides, 3 chalcones and 13 proanthocyanidins. The relative content of flavonoid metabolites accumulated continuously during the development of E. ferox seeds, and reached the highest at T30. In transcriptome, the expression of key genes in the flavonoid pathway, such as PAL, CHS, F3H, FLS, ANS, was highest in T30, which was consistent with the trend of metabolites. Six candidate transcription factors (R2R3MYBs and bHLHs) may affect the biosynthesis of flavonoids by regulating the expression of structural genes. Furthermore, transcriptome analysis and exogenous ABA and SA treatment demonstrated that ABA (PYR1, PP2Cs, SnRK2s) and SA (NPR1) are involved in the positive regulation of flavonoid biosynthesis. This study clarified the differential changes of flavonoid metabolites during the development of E. ferox seeds, confirmed that ABA and SA promote the synthesis of flavonoids, and found key candidate genes that are involved in the regulation of ABA and SA in the positive regulation of flavonoid biosynthesis.

Small Auxin Up RNAs influence the distribution of indole-3-acetic acid and play a potential role in increasing seed size in Euryale ferox Salisb.

BACKGROUND: Aquatic Euryale ferox Salisb. is an economically important crop in China and India. Unfortunately, low yield limitations seriously hinder market growth. Unveiling the control of seed size is of remarkable importance in improvement of crops. Here, we generated a new hybrid line (HL) with larger seeds by crossing South Gordon Euryale and North Gordon Euryale (WT) which hasn't been reported before. However, the functional genes and molecular mechanisms controlling the seed size in Euryale ferox Salisb. remain unclear. In this study, we focused on the differentially expressed genes in the auxin signal transduction pathway during fruit development between HL and WT to explore candidate regulatory genes participated in regulating seed size. RESULTS: Both concentration and localization of indole-3-acetic acid (IAA) at two growth stages of fruits of WT and HL were detected by LC-MS and immunofluorescence. Although IAA content between the two lines did not differ, IAA distribution was significantly different. To elucidate the mechanism and to seek the key genes underlying this difference, RNA-seq was performed on young fruits at the two selected growth stages, and differentially expressed genes related to the auxin transduction pathway were selected for further analysis. CONCLUSION: Hybrid Euryale ferox Salisb. expressed significant heterosis, resulting in non-prickly, thin-coated, large seeds, which accounted for the significantly larger yield of HL than that of WT. Our study indicated that Small Auxin Up RNAs (SAURs) -mediated localization of IAA regulates seed size in Euryale ferox Salisb. We found that some SAURs may act as a positive mediator of the auxin transduction pathway, thereby contributing to the observed heterosis.

Physiological and biochemical responses of Makhana (Euryale ferox) to gamma irradiation.

The impact of gamma irradiation on growth and physiology of Euryale ferox was described in the present investigation. E. ferox is an underutilized aquatic food crop that grows in shallow-water bodies in lower Assam regions and north Bihar of India. The seeds of E. ferox were irradiated with different doses of gamma irradiation ranging from 0 to 500 Gy. It was observed that the germination and survival percentage was inhibited by increasing the irradiation dose. However, plants developed from seed exposed to an irradiation dose beyond 100 Gy did not survive more than 1 month. Further growth parameters (leaf size and number, number of thorns, root number and length, and number of flower and seeds) were also compared with respect to non-irradiated plants. Physiological parameters, viz. chlorophyll a, chlorophyll b, total chlorophyll, photosynthetic rate, transpiration rate, stomatal conductance, and intracellular CO2 content was higher in the irradiation population of E. ferox. Superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities were observed low in irradiated population of E. ferox. The proline and glycine betaine content was enhanced with increasing the irradiation dose. The present investigation explores the potential use of gamma rays in genetic improvement of E. ferox and improves understanding of the physiological responses inflicted by gamma irradiation.

Development of microsatellite markers for Euryale ferox (Nymphaeaceae), an endangered aquatic plant species in Japan.

PREMISE OF THE STUDY: Microsatellite markers were developed to investigate genetic diversity and genetic structure of Euryale ferox, a vulnerable aquatic plant. METHODS AND RESULTS: Ten microsatellite loci were isolated and characterized for this species. Eight loci showed polymorphisms with two or three alleles per locus. As for the polymorphic markers, the expected and observed heterozygosities ranged from 0.00 to 0.08 and 0.17 to 0.64, respectively. CONCLUSIONS: The 10 microsatellite markers described here will be useful for investigating genetic diversity, genetic structure, and gene flow between populations of E. ferox.