Fig 1.
The effect of Pro-Ca on rice seedlings’ phenotype under salt stress.
The phenotype at 0h(A), 6h(B), 12h(C), and 24h(D). Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Scale bar = 5cm.
Fig 2.
The effect of Pro-Ca on rice seedlings morphology under salt stress.
Plant height (A), stem base width (B), leaf area (C), and shoot dry weight (D) under no stress and salt stress (50 mmol·L−1) with or without Pro-Ca (100 mg·L−1) spray. Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Values represent mean ± SE (n = 3), and different lowercase letters indicate significant differences according to Duncan’s test.
Fig 3.
Exogenous prohexadione-calcium (Pro-Ca) application conferred salt stress resistance of rice seedlings.
K+ content (A), Na+ content (B), and K+/Na+(C) under no stress and salt stress (50 mmol·L−1) with or without Pro-Ca (100 mg·L−1) spraying. Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Values represent mean ± SE (n = 3), and different lowercase letters indicate significant differences according to Duncan’s test.
Table 1.
Summary of sequence data.
Fig 4.
Analysis of DEGs under Pro-Ca treatment in response to salt stress.
Numbers of DEGs (A), KEGG enrichment of up-regulated (B) and down-regulated (C) DEGs in S vs. S + Pro-Ca at the same treatments times, and Summary of Gene Ontology (GO) categories of the up-regulated (D) and down-regulated (E) DEGs in S vs. S + Pro-Ca at the same treatment times, respectively. Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application.
Fig 5.
Exogenous prohexadione-calcium (Pro-Ca) application conferred salt stress resistance of rice seedlings.
Chl a content (A), Chl b content (B), Car content (C), total chlorophyll content (D), net photosynthetic rate (E), stomatal conductance (F), transpiration rate (G), and photosynthesis and chlorophyll metabolism-related gene (H) under no stress and salt stress (50 mmol·L−1) with or without Pro-Ca (100 mg·L−1) spraying. The expression level changes of genes in each group were described as log2 fold change of FPKM. Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Values represent mean ± SE (n = 3), and different lowercase letters indicate significant differences according to Duncan’s test.
Fig 6.
Exogenous prohexadione-calcium (Pro-Ca) application conferred salt stress resistance of rice seedlings.
SOD (A), POD (B), APX (C) activity content and antioxidant enzyme activities-related gene (D) under no stress and salt stress (50 mmol·L−1) with or without Pro-Ca (100 mg·L−1) spraying. The expression level changes of genes in each group were described as log2 fold change of FPKM. Abbreviations: CK, control (normal water); S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Values represent mean ± SE (n = 3), and different lowercase letters indicate significant differences according to Duncan’s test.
Fig 7.
Validation of key differentially expressed genes.
Relative expression level: The relative expression level of 5 genes obtained by quantitative real-time PCR (qRT-PCR) analysis; FPKM: The expression level of 5 genes is based on the fragments per kilobase of transcripts per million mapped fragments (FPKM) value. The error bars represent the SE from three replicates. Abbreviations: S, salt stress; and S + Pro-Ca, salt stress plus foliar Pro-Ca application. Values represent mean ± SE (n = 3); *: P<0.05 (Relative expression level); **: P<0.01 (Relative expression level).
Fig 8.
Schematic diagram of the mechanism by which prohexadione-calcium promotes rice seedlings development under salt stress by regulating antioxidant processes and photosynthesis.