Fig. 8

Mannitol and n-butanol stress recovery (MANB-R4) relates to continuous MT regeneration in embryogenic microspores. A1-A6 Late uni-nucleate microspore with a large vacuole (V). A1 Most cortical and subcortical MT assembly into long, thin bundles without a preferential orientation. A2-A3 Some thick bundles of CMT encircling the midplane of the nucleus (N) resembling a PPB-like structure. Scarce, fine, and very short EMT in the remaining cytoplasm above the nucleus (A3). A4-A6 3D model of the subcellular volume of a similar structure. Some thick bundles of CMT formed a ‘ring’ around the nucleus (N) of microspore resembling a narrow PPB-like structure. Superior visualisation axis model (A4). Volumetric ortho-slicer view from the forward (a5) and opposite site of the microspore model (A6). B1-B3, C1-C3 Bi-nucleate embryogenic structures. B1 Numerous long and thin CMT. B2-B3 Reticulate network of long EMT extending to the cortex around the sister nuclei (N). C1 Thin and very short CMT. C2-C3 Dense network of MT in the cytoplasm at the opposite pole to the nuclei (N). Long bundles of EMT encircling both nuclei and growing in the direction of the cortex. Cortex - CMT; z-series projected as a maximum intensity projection from cortex optical sections collected from the front (F) or from the back (B) side of microspore. Middle - optical section at the middle of the z-series. Middle+(Sub)Cortex B - Endoplasmic and (sub)cortical MT; z-series projected as a maximum intensity projection from middle and cortical optical sections collected from the back side (B) of microspore. Inserts on the upper-right corner in the first panels show a corresponding image in the differential interference contrast (DIC). The dashed line indicates the axis between the operculum (O) and the opposite pole. Prj - z-series projected as a maximum intensity from the front side (Prj F) or from the back side (Prj B) of microspore. Green fluorescence (Alexa 488) shows α-tubulin. Red fluorescence of nuclei is caused by PI staining. Red autofluorescence of exine. Scales =20 μm