Figure 5.

Effect of SiR impairment on the sulfite network enzyme activities. The top (1-2L), the third (3L), and the fifth (5L) leaves (counted from the tops) were collected from 1-month-old SIR Ri and wild-type (WT) tomato plants; enzyme assays in the leaves were performed as described in “Materials and Methods.” The presented values are average ± se (n = 3), where data for SIR Ri plants represent the average of the activities detected in SIR Ri37 and SIR Ri40 plants. ATPS activity is expressed as nmol ATP mg^–1 protein min^–1, SiR activity is expressed as nmol Cys mg^–1 protein min^–1, and SO, ST, and APR activities are expressed as nmol sulfite mg^–1 protein min^–1. The values denoted by different letters are significantly different according to the Tukey-Kramer honestly significant difference mean-separation test (JMP 8.0; P < 0.05). The uppercase letters reflect differences between leaves of the same genotype; the lowercase letters distinguish different genotypes.