Fig. 4.

AtNRP1 and AtNRP2 are involved in ER stress–induced cell death in Arabidopsis. a Loss of AtNRP1 and AtNRP2 function attenuated ER–stress induced chlorophyll loss in Arabidopsis. ER stress was induced by transferring atnrp1 and atnrp2 seedlings to MS medium containing 5 μg/μLtunicamycin. Photography was taken 2 days after ER stress induction. b Chlorophyll content of knockouts, atnrp1–complementing and AtNRP2–overexpressing lines under ER stress. The chlorophyll content of seedlings from the genotypes, as indicated in the figure, was determined 24–h after tunicamycin treatment. c Expression levels of AtNRP1 in complementing lines and AtNRP2 in overexpressing lines. Total RNA was isolated from 7 days-old Arabidopsis seedlings, genotypes atnrp1 transformed with 35S: AtNRP1 and Col–0 transformed with 35S: AtNRP2. The transcript levels of AtNRP1 or AtNRP2, as indicated, were quantified by qRT–PCR. Gene expression was calculated using the 2^-ΔCt method and Actin as endogenous control. Values are mean ± S.D. from three replicates. d Evans blue staining of Arabidopsis seedlings treated with 5 μg/mL tunicamycin or DMSO. Col–0, atnrp1, atnrp2, atnrp1–complementing line and AtNRP2–overexpressing lines were treated with tunicamycin for 24 h and stained with Evans blue