Figure 2.
Comparison of Antioxidant Defense Gene Expression in rax1-1 and cad2-1.
(A) PCR-based detection of APX2 transcript under nonstress conditions in rax1-1 and cad2-1. 3′RACE PCR-amplified APX2 and APX1 cDNAs were detected by autoradiography as in the legend of Figure 1B. The wild-type control (EL WT) is from 10-fold excess light (EL) stressed plants, and loading of the APX2-specific product was 1% that of the volume loaded for the mutants. The APX1 is shown here as a PCR control for all cDNA samples. Each sample is pooled from six plants. LL, low light.
(B) Steady state levels of transcripts of antioxidant defense genes in nonstressed wild type, cad2-1, and rax1-1. RNA gel blots loaded with 20 μg of total RNA were hybridized to specific probes and washed at high stringency, and images were developed using a phosphoimager (see Methods). The RNA preparations of rax1-1 and cad2-1 were the same as those in (A). The numbers below each row are values of signal relative to the wild type from this experiment, calculated from densitometer readings derived from the digitized images (Fryer et al., 2003). The band below each group is actin mRNA used as a loading control (see Methods).
(C) rax1-1–responsive gene expression in excess light–exposed and systemic leaves. Steady state levels of transcripts encoded by antioxidant defense genes in the wild type (n = 3) partially exposed to excess light (15-fold). RNA was prepared from directly exposed leaves (EL) and nonexposed leaves that responded systemically to this stress (S; Karpinski et al., 1999), compared with low light nonstressed controls (LL). The amounts of RNA used and the processing of the blots was as in (B).