Measurement of adhesive strength between the epidermal and inner tissues of plant stems using a tensile tester

BackgroundThe plant stem is composed of epidermal and inner tissues that are under tension and compression, respectively. Therefore, the adhesion of both tissues is considered to be involved in the structural integrity of the stem. However, the role of tissue adhesion in stem structure is unclear.ObjectiveThis study aimed to develop a method for quantitatively measuring the adhesive strength between the epidermal and inner tissues using a tensile tester to determine the possible role of tissue adhesion in stem integrity.MethodsThe epidermal tissue was partially peeled from the segment of pea epicotyls using forceps to create a peeling arm. The peeling arm and the segment region of the partially removed epidermal tissue were fixed to the upper and lower clamps, respectively. By raising the upper clamp at various speeds, the epidermal tissue was peeled from the segment, and the peeling force was recorded.ResultsAdhesive strength was defined as the peeling force normalized by the width of the peeled epidermal tissue. The peeling rate was determined as 100 mm/min. The adhesive strength in the elongation region of the stem was substantially smaller than in the non-elongation region.ConclusionsA method for quantitatively measuring the adhesive strength between the epidermal and inner tissues was developed. Analysis using this method suggests that adhesive strength may be involved in regulating stem growth.