Figure 4.

HPCA1 is required for local and systemic expression of stress-acclimation transcripts, as well as acclimation of plants to light stress. A, Real-time quantitative PCR analysis of APX2, MYB30, ZAT10, ZAT12, and ZHD5 expression in local and systemic leaves of WT and hpca1-1 plants subjected to a local HL treatment. Transcripts tested were previously found to respond to HL stress in WT plants. Results are presented as relative quantity (RQ) compared to control WT from local leaf. B, Averaged measurements of leaf injury (increase in ion leakage) of WT and hpca1-1 plants. Measurements are shown for unstressed plants (control), local leaves subjected to a pretreatment of HL stress before a long HL stress period (local acclimation), systemic leaves of plants subjected to a local HL stress pretreatment before a long period of local HL stress was applied to a systemic leaf (systemic acclimation), and systemic leaves of plants subjected to a long HL stress period without pretreatment (HL without pretreatment). Results are presented as percent of control (leaves not exposed to HL stress). All experiments were repeated at least three times with 10 plants of each genotype per experiment. Data is presented in (A) as box plot graphs; X is mean ± se, N = 30, *P < 0.05, **P < 0.01, ***P < 0.001, Student t-test. Data are presented in (B) as box plot graphs where X is mean ± se, N = 30, one-way ANOVA followed by a Tukey test; lowercase letters donate significance (P < 0.05).