Euryale ferox Salisb., an annual aquatic plant, is the only species in the genus Euryale in the Nymphaeaceae. Seeds of E. ferox are a nutritious food and also used in traditional Chinese medicine (Qian Shi in Mandarin). The molecular events that occurred during seed development in E. ferox have not yet been characterized. In this study, we performed transcriptomic analysis of four developmental stages (T1, T2, T3, and T4) in E. ferox seeds with three biological replicates per developmental stage to understand the physiological and biochemical processes during E. ferox seeds development. 313,844,425 clean reads were assembled into 160,107 transcripts and 85,006 unigenes with N50 lengths of 2052 bp and 1399 bp, respectively. The unigenes were annotated using five public databases (NR, COG, Swiss-Prot, KEGG, and GO). In the KEGG database, all of the unigenes were assigned to 127 pathways, of which phenylpropanoid biosynthesis was associated with the synthesis of secondary metabolites during E. ferox seed growth and development. Phenylalanine ammonia-lyase (PAL) as the first key enzyme catalyzed the conversion of phenylalanine to trans-cinnamic acid, then was related to the synthesis of flavonoids, lignins and alkaloid. The expression of PAL1 reached its peak at T3 stage, followed by a slight decrease at T4 stage. Cytochrome P450 (P450), encoded by CYP84A1 (which also called ferulate-5-hydroxylase (F5H) in Arabidopsis), was mainly involved in the biosynthesis of lignins. Our study provides a transcriptomic analysis to better understand the morphological changes and the accumulation of medicinal components during E. ferox seed development. The increasing expression of PAL and P450 encoded genes in phenylpropanoid biosynthesis may promote the maturation of E. ferox seed including size, color, hardness and accumulation of medicinal components.

Trapa (Lythraceae) is an aquatic plant genus widely distributed in the old world. Although Trapa species have great edible and medical value, studies related to species identification and utilization are still lacking. Here, we reported the complete chloroplast genome sequence of a cultivated species, T. bicornis. The chloroplast genome size of T. bicornis was 155,539 bp, consisting of a pair of inverted repeat (IR) regions (24,386 bp), separated by a large single copy (LSC) region (88,493 bp) and a small single copy (SSC) region (18,274 bp). A total of 130 genes were annotated, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The phylogenomic analysis supported the monophyly of Trapa, and a sister relationship between T. bicornis and T. natans.

Climate change poses a threat to both the natural habitat and the sustainable production of Euryale ferox, a valuable aquatic crop. To address this issue, our study employed an optimized Maximum Entropy (MaxEnt) model to project the climatic suitability of E. ferox distribution in China for the 2030-2070 s under four climate scenarios. Utilizing 130 occurrence records of E. ferox and 20 ecological factors, we identified four primary factors influencing the distribution of E. ferox. The optimal conditions for E. ferox include elevations below 184.8 m, the temperature of the warmest season exceeds 25.7°C, the precipitation of the wettest month ranging between 167 and 718 mm, and precipitation over 9.5 mm in the driest month. The accuracy of the MaxEnt model predictions was comprehensively evaluated by the area under the ROC curve (AUC = 0.942) and the true skill statistic (TSS = 0.783), indicating its effectiveness in forecasting suitable environments. We also found that the current areas of highly and moderately suitable habitats are 0.909 × 10⁵ km² and 3.324 × 10⁵ km², respectively. Compared to the current scenario, future projections indicate a significant increase in suitable areas. Furthermore, except for SSP245, the distribution centroid is projected to move southwestward then northward under other climate scenarios. These findings suggest that climate change may broadly benefit the expansion of E. ferox, offering critical insights for the formulation of regional conservation and cultivation strategies.

Analysis of SSR Information in Aquatic Plant Euryale ferox Salisb Transcriptome