FIGURE 7.

The induced-photooxidative stress tolerance in leaves after B. japonicum inoculation depends on Nod factors- and AON-signaling pathways. The first trifoliate leaf of 12-days-old nfr5- and nark-mutant soybean plants and wild type (wt) plants were sprayed with 20 μM paraquat (PQ) after 48 h of root inoculation with B. japonicum (I). Non-inoculated plants were used as a control (C). The chlorophyll content, SPAD, maximum quantum efficiency of Photosystem II (F_v/F_m), sugars and MDA content, photosynthesis, stomatic conductance, performance index and the ferric reducing ability of plasma (FRAP) were analyzed 24 h after PQ treatment. (A) Performance index (PI) was set as an indicator of the overall fitness of the photosynthetic apparatus. (B) Net photosynthesis. Data are means ± SE of nine leaves of three independent experiments. Asterisks indicate significant differences between control and inoculated plants (p < 0.05, Tukey test). (C) Biplot from the first and second principal components (PC1 and PC2) of principal components analysis (PCA) showing relationships between inoculated wt plants and SPAD; Performance Index; F_v/F_m; Photosynthesis; Stomatic conductance and FRAP.