Figure 1

P. kirkii extracts disrupt root anisotropic growth. (a) Left, optical longitudinal sections of mPS-PI-stained Arabidopsis roots. Progressive swelling of treated root cells transitioning to the elongation zone is apparent. Asterisks mark the root quiescent centre. Bar = 100 µm. Right, corresponding cross sections highlighting the epidermal and cortical radial expansion in treatment. Numbers in brackets indicate the mean of section diameters with standard deviation (n = 12). v vasculature, en endodermis, c cortex, ep epidermis. Bar = 100 µm. (b) Left, cortical cell length in function of the distance to the quiescent center (QC). Dataset represents fifteen seedlings per treatment, curves were fitted with the Gompertz model, circles indicate data distribution. Dotted lines delimit the distinct apical root zones. Middle, cortical cell length in the given root apical zone. Significant differences between treatment and water control were analysed in two-sided unpaired t-tests (p-values are indicated). Right, cortical cell length in function of the position from QC initials. Data represent mean values; curves were fitted with the exponential growth model, standard errors are indicated. Significant differences between treatment and untreated control for each position were analysed in two-sided unpaired t-tests (*p-value < 0.05). MZ meristematic zone, TZ transition zone, EZ elongation zone.