Figure 4.

Branched arbuscules are metabolically active after P treatment. Rice roots colonized with R. irregularis were treated with water or 0.5 mM Pi at 14 dpp. Roots were subjected to fungal vital staining or WGA-FITC staining at 4 or 20 h after the treatments. To calculate the total number of branched arbuscules per plant, numbers of colonized regions per plant (n = 5, biologically independent) were first determined. Then, numbers of branched arbuscules in each colonized region (n = 5, in each plant) were counted (Supplemental Fig. S5). The total numbers of branched arbuscules per plant were determined by multiplying the number of colonized regions and the average value of the numbers of branched arbuscules in colonized region. Data are presented as means ± sd. Two-way ANOVAs were performed on the data, with treatments (water/P) and staining method (WGA/vital staining) as factors for each time point separately. Staining methods had no significant effect on the number of branched arbuscules per plant, while P treatments had significant effects (P < 0.01).