The possible involvement of Ca2+ as a second messenger in snapdragon (Antirrhinum majus L.) shoot gravitropism, as well as the role of ethylene in this bending response, were analyzed in terms of stem curvature and gravity-induced asymmetric ethylene production rates, ethylene-related metabolites, and invertase activity across the stem. Application of CaZ+ chelators (ethylenediaminetetraacetic ...

One of the reasons for relatively high biomass harvesting cost is challenges in adjusting the ground speed of harvesting machines with respect to the yield level within a field. A real-time biomass yield sensor that can predict the yield in front of a machine could be a useful tool to control ground speed. It was hypothesized that the force required to bend Miscanthus stems is a reliable predic...

Mechanical signals are important factors that control plant growth and development. External mechanical loadings lead to a decrease in elongation and a stimulation of diameter growth, a syndrome known as thigmomorphogenesis. A previous study has demonstrated that plants perceive the strains they are subjected to and not forces or stresses. On this basis, an integrative biomechanical model of me...

Shearing stress of wheat stalk was measured for four moisture content levels (15, 25, 35 and 45%, w.b.), three cutting heights (100, 200 and 300 mm), two types of cutting knives, smooth and serrated edge and three blades oblique angle (0, 15 and 30 deg.). The results of data analysis showed that the shearing stress of wheat stems decreased as the moisture content decreased. The shearing force o...

We address the mechanism by which adult intestinal stem cells (ISCs) become localized to the base of each villus during embryonic development. We find that, early in gut development, proliferating progenitors expressing ISC markers are evenly distributed throughout the epithelium, in both the chick and mouse. However, as the villi form, the putative stem cells become restricted to the base of t...

A mathematical model is presented to examine the propagation of bending waves on a plant stem that are induced by vibratory excitation from an attached insect. This idealized model represents the insect body as a mass and the legs as a linear spring along with a general time-varying force that is assumed to act in parallel with the spring. The spring connects the mass to a stem modeled as a bea...

Using Avena sativa L. cv. Victory oat seedlings and excised p-1 stem segments (including the p-1 and p-2 internodes) the effect of exogenously supplied ethylene and the removal of ethylene on internodal extension and gravitropic bending was assessed. Similarly, the ability of the excised system to respond to gravistimulation was assessed in the presence of inhibitors of ethylene action (AgNO3)...

The relationship between evoked electrical activity and stem movements in three-week old sunflowers was demonstrated. Electrical potential changes (recorded by Ag/AgCl extracellular electrodes) and time-lapse images (from a top view camera) were recorded and analyzed. A heat stimulus applied to the tip of one of the second pair of leaves evoked a variation potential, transmitted basipetally alo...

Myosins and actin filaments in the actomyosin system act in concert in regulating cell structure and dynamics and are also assumed to contribute to plant gravitropic response. To investigate the role of the actomyosin system in the inflorescence stem gravitropism, we used single and multiple mutants affecting each of the 17 Arabidopsis myosins of class VIII and XI. We show that class XI but not...