Maturation stress generation starts before the formation of the G-layer in poplar tension wood

Tension wood is widespread in organs of woody plants. During its formation, it generates large tensile mechanical stress, called maturation stress [1]. This stress performs essential biomechanical functions such as optimizing the stem mechanical resistance, performing adaptive movements and ensuring long-term stability of growing plants. The mechanism generating this stress is not yet fully understood, although various hypotheses have recently been proposed [2-6]. In order to discriminate between these hypotheses, we investigated structural changes in cellulose microfibrils along sequences of xylem cell differentiation in tension and normal wood of poplar.