Genetic canalization of nutrient resorption in the widespread grass Phragmites australis under salt stress
- Key Laboratory of Ecological Prewarning, Protection and Restoration of Bohai Sea, Ministry of Natural Resources, School of Life Sciences, Shandong University, China
- National Natural History Museum of China, China
- Ecology and Nature Conservation Institute, Chinese Academy of Forestry, No.1 Dongxiaofu, Xiangshan Road, Haidian district, China
- School of Renewable Natural Resources, Louisiana State University Agricultural Center, United States
Figures
Figure 1 with 1 supplement
Metabolomic responses of Phragmites australis to salinity stress.
(a) Principal component analysis (PCA) score plot of the metabolome (3413 metabolites) under control (blue) and salt (red) treatments. Ellipses represent 95% confidence intervals for each group. PERMANOVA (Euclidean distance, 9999 permutations) with genotype as covariate revealed a significant effect of salinity (p<0.001). (b) Volcano plot showing differential accumulation of metabolites between salt and control groups. Red points indicate metabolites that are significantly different (|log₂ fold change|>1, false discovery rate <0.05, variable importance in projection >1). Selected stress-responsive metabolites (e.g., N,N-dimethylglycine, sucrose 6-phosphate, glutathione) are labeled.
Figure 1—figure supplement 1
The common garden pictures in an early stage.
Figure 2 with 2 supplements
Effects of salinity on biomass and sodium accumulation in Phragmites australis.
(a) Biomass of control and salt-treated plants (harvest at the final stage). Data are means ± SE. ***p<0.001 (Welch’s t-test, n=106 per group). (b) Sodium (Na) concentrations in green, yellow, and brown leaves under control and salt conditions. Data are means ± SE. ***p<0.001 (Welch’s t-test for each stage, n=105–106 per group per stage).
Figure 2—figure supplement 1
Principal component analysis (PCA) of leaf elemental composition across Phragmites australis lineages, salinity treatments, and developmental stages.
(a) Global PCA of all samples, with points colored by salinity treatment (control: blue, salt: red). Arrows represent element loadings scaled by a factor of 3; arrow colors indicate functional groups of elements. The MANOVA test (Pillai’s trace) revealed a significant overall effect of salinity on PC1 and PC2 combined (p<0.001). (b, c) Boxplots of PC1 and PC2 scores comparing control and salt treatments, with t-test results (Welch’s t-test) displayed above each panel (*p<0.05, **p<0.01, ***p<0.001, ns: not significant). (d–r) PCA subplots for each combination of lineage (AU, CN_E, CN_N, EU, EU_NA) and developmental stage (Green, Yellowing, Litter). Background gray points represent all samples, while colored points highlight the focal lineage ×stage combination, with colors indicating salinity treatment. The significance of salinity effect within each combination (MANOVA on PC1 and PC2) is shown in the subplot title (***p<0.001, **p<0.01, *p<0.05, ns: not significant).
Figure 2—figure supplement 2
Principal component analysis of nitrogen (N), phosphorus (P), and potassium (K) concentrations in green leaves and leaf litter.
(a) Ordination of samples from control and salt treatments across the first two principal components (PC1 and PC2). (b) Vector loadings of individual elements, indicating their contribution and direction of influence on the principal components.
Figure 3 with 1 supplement
Geographical distribution (a) of the phylogeographic groups of Phragmites australis and leaf nutrient resorption efficiency (b–d) for nitrogen (N), phosphorus (P), and potassium (K).
Phylogeographic groups reflect deep evolutionary lineages defined by genetic markers (e.g., chloroplast haplotypes). Statistical significance was assessed using linear mixed-effects models that included genotype as a random effect to accommodate the paired experimental design. The p-values shown in panels (b–d) refer to the fixed effects of group, salinity, and their interaction. When significant group effects were detected, post hoc pairwise comparisons were performed separately within each salinity treatment using Tukey’s HSD test; different letters denote statistically significant differences (α=0.05). Data are means ± SE. Sample sizes were n = 7 (AU), 37 (CN_E), 36 (CN_N), 10 (EU), and 13 (EU_NA) per treatment.
Figure 3—figure supplement 1
Differences in nutrient resorption efficiency (Δ=Salt – Control) among phylogeographic groups of Phragmites australis.
Box plots showing the within-genotype difference (Δ) in nitrogen (N), phosphorus (P), and potassium (K) resorption efficiency between salt and control treatments for each phylogeographic group. The Δ value was calculated as the response under salt treatment minus the response under control treatment for the same genotype. The horizontal dashed line at Δ=0 indicates no change. Boxes represent the interquartile range (IQR), the middle line denotes the median, and whiskers extend to 1.5×IQR. Individual points represent values for each genotype. Positive Δ values indicate higher resorption under salt treatment, whereas negative values indicate lower resorption. No significant differences were found among phylogeographic groups in their Δ values for N, P, or K (one-way ANOVA, p>0.05).
Figure 4 with 1 supplement
Geographical distribution (a) of Phragmites australis ecotypes and leaf nutrient resorption efficiency (b–d) for nitrogen (N), phosphorus (P), and potassium (K).
The color scheme represents habitat-based adaptations and is independent of that used in Figure 3. Ecotypes categorize populations according to adaptive phenotypes to specific local habitats (freshwater wetlands, coastal saltmarsh, inland saltmarsh). Significance was tested with linear mixed-effects models incorporating genotype as a random effect to account for paired measurements. The reported p-values correspond to the fixed effects of ecotype, salinity, and their interaction. Where ecotype effects were significant, post hoc Tukey’s HSD comparisons were conducted within each salinity level; different letters indicate statistically significant differences (α=0.05). Data are means ± SE. Sample sizes were n = 20 (freshwater), 39 (saltmarsh), and 10 (saltmarsh_inland) per treatment.
Figure 4—figure supplement 1
Differences in nutrient resorption efficiency (Δ=Salt – Control) among ecotypes of Phragmites australis.
Box plots showing the within-genotype difference (Δ) in nitrogen (N), phosphorus (P), and potassium (K) resorption efficiency between salt and control treatments for each ecotype. The Δ value was calculated as the response under salt treatment minus the response under control treatment for the same genotype. The horizontal dashed line at Δ=0 indicates no change. Boxes represent the interquartile range (IQR), the middle line denotes the median, and whiskers extend to 1.5×IQR. Individual points represent values for each genotype. Positive Δ values indicate higher resorption under salt treatment, whereas negative values indicate lower resorption. No significant differences were detected among ecotypes in their Δ values for N, P, or K (one-way ANOVA, p>0.05).
Figure 5 with 1 supplement
Assessment of three control strategies for nutrient resorption in Phragmites australis under varying salinity levels.
(a–c) Relationship between nutrient concentrations (N, P, K) in green leaves and senesced litter. (d, g) Association between phosphorus and nitrogen resorption efficiencies. (e, h) Linkage between resorbed N:P(K) ratios and green leaf N:P(K) ratios. (f, i) Correlation between log₁₀-transformed resorbed N:P(K) and log₁₀-transformed green leaf N:P(K) ratios. The gray dashed line in each panel indicates the 1:1 reference. Solid lines represent significant relationships (p<0.05 for the standardized major axis [SMA] regression model), while dashed lines indicate nonsignificant relationships. Statistical annotations show results from SMA regression for each salinity level: β (with asterisks) is the SMA slope, where asterisks after β indicate significant deviation from 1 (*p<0.05, **p<0.01, ***p<0.001), and asterisks after R2 indicate significance of the SMA regression model.
Figure 5—figure supplement 1
Assessment of three control strategies for nutrient resorption in Phragmites australis under varying salinity levels using ordinary least squares (OLS) regression.
(a–c) Relationship between nutrient concentrations (N, P, K) in green leaves and senesced litter. (d, g) Association between phosphorus and nitrogen resorption efficiencies. (e, h) Linkage between resorbed N:P(K) ratios and green leaf N:P(K) ratios. (f, i) Correlation between log₁₀-transformed resorbed N:P(K) and log₁₀-transformed green leaf N:P(K) ratios. The gray dashed line in each panel indicates the 1:1 reference. Solid lines represent significant relationships (p<0.05 for the OLS regression model), while dashed lines indicate nonsignificant relationships. Statistical annotations show results from OLS regression for each salinity level: β (with asterisks) is the OLS slope, where asterisks after β indicate significant deviation from 1 (*p<0.05, **p<0.01, ***p<0.001), and asterisks after R2 indicate significance of the OLS regression model.
Figure 6 with 1 supplement
Influence of latitude on leaf nitrogen (N), phosphorus (P), and potassium (K) resorption efficiencies of Phragmites australis.
(a) Influence of latitude on leaf nitrogen (N) resorption efficiency. (b) Influence of latitude on leaf phosphorus (P) resorption efficiency. (c) Influence of latitude on leaf potassium (K) resorption efficiency. The analysis was performed using linear mixed-effects models, treating phylogeographic groups as a random effect.
Figure 6—figure supplement 1
Comparison of raw and carbon-standardized nutrient resorption efficiency (NuRE) for N, P, and K.
Points represent genotype-by-treatment observations (n=206), colored by treatment. Gray dashed lines indicate the 1:1 relationship, and black lines show ordinary least-squares fits. Pearson’s r and the mean standardized-minus-raw difference (Δmean, percentage points) are shown.
Tables
Table 1
Individual effects (R²) of absolute latitude of origin, nutrient concentration, and nutrient stoichiometry on leaf N, P, and K resorption, estimated using linear mixed-effects models with phylogeographic group as a random intercept.
Individual marginal R2 values were calculated by hierarchical partitioning using glmm.hp. Asterisks indicate the significance of the corresponding fixed effects in the full models: *p<0.05; **p<0.01; ***p<0.001.
| Latitude | Concentration | Stoichiometry | |
|---|---|---|---|
| N | 0.092*** | 0.044*** | – |
| P | 0.057** | 0.006 | <0.001 |
| K | 0.094*** | 0.043 | 0.078 ** |
Additional files
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Supplementary file 1
The lineages of Phragmites australis in the common garden.
- https://cdn.elifesciences.org/articles/111792/elife-111792-supp1-v1.docx
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MDAR checklist
- https://cdn.elifesciences.org/articles/111792/elife-111792-mdarchecklist1-v1.docx
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Genetic canalization of nutrient resorption in the widespread grass Phragmites australis under salt stress
eLife 15:RP111792.
https://doi.org/10.7554/eLife.111792.3
