Dataset For Melogno PNAS2023-20470

Although the formation of new walls during plant cell division tends to follow maximal tensile stress direction, analyses of individual cells over time reveal a much more variable behavior. The origin of such variability, as well as the exact role of interphasic microtubule behavior before cell division have remained mysterious so far. To approach this question, we took advantage of the Arabidopsis stem, where the tensile stress pattern is both highly anisotropic and stable. Although cortical microtubules generally align with maximal tensile stress, we detected a specific time window, ca. 3 hours before cell division, where cells form a radial pattern of cortical microtubules. This microtubule array organization preceded preprophase band formation, a transient cortical microtubule array predicting the position of the future division plane. It was observed under different growth conditions, and was not related to cell geometry or polar auxin transport. Interestingly, this cortical radial pattern correlated with the well-documented increase of cytoplasmic microtubule accumulation before cell division. This radial organization was prolonged in cells of the <i>trm678</i> mutant, where cortical microtubules are unable to form a preprophase band. Whereas division plane orientation in <i>trm678</i> is noisier, we found that cell division symmetry was in contrast less variable between daughter cells. We propose that this “radial step” reflects a trade-off in robustness for two essential cell division attributes: symmetry and orientation. This involves a “reset” stage in G2, where an increased cytoplasmic microtubule accumulation transiently disrupts cortical microtubules alignment with tissue stress.