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. 2018 May 14;9:633. doi: 10.3389/fpls.2018.00633

FIGURE 3.

FIGURE 3

Nodules and nitrogenase activity of WT and cas31 mutants. (A) Relative expression of MtCAS31 in nodules after inoculation of rhizobium S. meliloti 1021 at selected time points. Values were normalized to ACTIN expression. Data represent the mean ± SD of three replications with 15 plants each. (B) Relative expression of MtCAS31 in nodules under dehydration. Values were normalized to ACTIN expression. (C) Relative expression of MtCAS31 in nodules under drought stress after two drought-rewater cycles (a drought-rewater cycle: withhold water for 7 days and rewater for 7 days). Values were normalized to ACTIN expression. (D) Nodules in WT and cas31 mutant under no stress condition and drought stress; bar = 2.5 mm. (E) Nodule number analysis in D. (F,i) Numbers of nodule in WT and cas31 mutants was scored at 28 dpi both under water-sufficient conditions and after two drought-rewater cycles. Data represent the mean ± SD of three replications with 15 plants each. Significance is indicated by letters; one-way ANOVA, LSD. (ii) Fresh weight of nodules per plant under no stress and drought stress conditions. Nodules from 28 dpi in different plant materials were used for analysis. Data represent the mean ± SD of three replications with 15 plants each. Significance is indicated by letters, one-way ANOVA, LSD. (iii) Pink nodules under no stress and drought stress conditions. Nodules from 28 dpi in different plant materials were used for analysis. Data represent the mean ± SD of three replications with 15 plants each. Significance is indicated by letters, one-way ANOVA, LSD. (iv) Acetylene reduction assay was used to analyze the nitrogenase activity in WT and cas31 mutants under no stress and drought stress conditions. Acetylene reduction represents nitrogenase activity. Seven-day-old seedlings were inoculated with rhizobium S. meliloti 1021. Seven days later, the inoculated plants were exposed to drought-rewater cycles. Acetylene reduction assay was conducted after two drought-rewater cycles (a drought-rewater cycle: withhold water for 7 days and rewater for 7 days) and under no stress conditions. Data represent the mean ± SD of three replications with 15 plants each. Significance is indicated by letters; one-way ANOVA, LSD.