Fig. 2.

Confocal microscopy images of the advanced stage root colonization by V592-GFP1 on Arabidopsis roots. (A) A mass of hyphae wrapping the root surface and displaying a non-specific growth pattern (2 dpi). (B) Hyphae tightly adhered on the root surface and grew along the longitudinal junction and extended across the transverse to penetrate into epidermal cells intercellularly (2 dpi). (C) The slight swelling of hyphae was followed by formation of a narrow infection peg (arrows) during perforation. (D) Hyphae adhered to the root surface along the longitudinal junction intercellularly across epidermal cells after penetration and internally grew parallel along the longitudinal axis bidirectional (3 dpi). (E) Compound micrograph of bright field transmission and corresponding fluorescence image displaying hyphal swelling intercellularly between the epidermal cell junctions at the site of penetration to an adjacent cell (3 dpi). (F) Hyphal net depicting the cellular structure of the root epidermis displaying intercellular colonization (4 dpi). (G) Hyphal net within the xylem vessel (5 dpi). (G′) Compound micrograph of bright field transmission and corresponding fluorescence images (same view as G). (H) Hyphal swellings (arrows) at the leading edge when hyphae extended transversally (7 dpi). (I) Hyphae extended acropetally up the xylem vessels to the above-ground tissues (10 dpi). Hyphae on the root surface displayed no fluorescence. (J) Hyphae extended to the lateral roots along the vascular tissues (10 dpi). (K) Hyphae extended toward the root tip zone and caused the root cap to collapse (12 dpi). (A–D, F and K) The root was stained with propidium iodide before photographs were taken