A tension-adhesion feedback loop in plant epidermis.

Abstract

Mechanical forces have emerged as coordinating signals for most cell functions. Yet, because forces are invisible, mapping tensile stress patterns in tissues remains a major challenge in all kingdoms. Here we take advantage of the adhesion defects in the <i>Arabidopsis</i> mutant <i>quasimodo1 (qua1)</i> to deduce stress patterns in tissues. By reducing the water potential and epidermal tension <i>in planta</i>, we rescued the adhesion defects in <i>qua1</i>, formally associating gaping and tensile stress patterns in the mutant. Using suboptimal water potential conditions, we revealed the relative contributions of shape- and growth-derived stress in prescribing maximal tension directions in aerial tissues. Consistently, the tension patterns deduced from the gaping patterns in <i>qua1</i> matched the pattern of cortical microtubules, which are thought to align with maximal tension, in wild-type organs. Conversely, loss of epidermis continuity in the <i>qua1</i> mutant hampered supracellular microtubule alignments, revealing that coordination through tensile stress requires cell-cell adhesion.