The root microtubule cytoskeleton and cell cycle analysis through desiccation of Brassica napus seedlings.

Desiccation tolerance (DT) of orthodox seeds is reduced upon their germination. The main aim of this study was to estimate the range of rape seedling DT by examining the consequences of desiccation on the distribution, stability and orientation of microtubules in diverse cells. Using different parameters, such as relative water content (RWC), the tetrazolium viability test and electrolyte leakage, it has been demonstrated that a small percentage decrease in relative humidity can cause irreparable changes in membrane permeability, as well as in nuclear structure and microtubule cytoskeleton stability. Seedling root tips survived when exposed to low desiccation stress intensity, but small changes in microtubule behavior were observed. Cortical microtubules formed thick arrays, especially near the plasma membrane. Water loss also resulted in a reduction of the mitotic activity. More rapid desiccation caused microtubule depolymerization. Occasionally, abnormal tubulin aggregates were visible. Cell divisions were not detectable under these conditions. Due to the observable microtubule defects, the hypersensitivity of the microtubule cytoskeleton might be a useful and simple parameter for estimating environmental stress intensity.