A tension-adhesion feedback loop in plant epidermis.

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 mutant to deduce stress patterns in tissues. By reducing the water potential and epidermal tension , we rescued the adhesion defects in , 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 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 mutant hampered supracellular microtubule alignments, revealing that coordination through tensile stress requires cell-cell adhesion.