Fig. 4.

Scanning electron microscopy showing the presence of biogenic crystals in the root tissues of susceptible and tolerant soybean cultivars when inoculated with P. sojae. a Cross section of the non-infected susceptible soybean cultivar, (b) Cross section of the infected susceptible soybean cultivar, (c) Cross section of the non-infected tolerant soybean cultivar, (d) Cross section of the infected tolerant soybean cultivar. Yellow arrows denote the presence of biogenic crystals in the vascular cylinder in copious amounts in both non-infected susceptible and tolerant cultivars. Biogenic crystals were present in the vascular cylinder in copious amounts in the non-infected and infected susceptible cultivar, and in non-infected tolerant cultivar but their quantity was reduced in infected tolerant cultivar. Bars: (a-d) 40 µm. Bar charts indicating the relative abundance of biogenic crystals in the vascular cylinder of soybean root as mean ± SE (e; n > 5). Significant differences between treatments showing biogenic crystals in the vascular cylinder of soybean root are indicated using letters (a-d) on top of the bars as described by Fisher’s LSD and ANOVA (α = 0.05)