The effects of mechanically-induced stress in plants ? a review

Abstract

Mechanically-induced stress (MIS) occurs naturally in plants as the aerial parts are moved, usually by wind, but also by such agents as rain and animals . It can be induced indoors by various actions such as rubbing or bending the stem or shaking or brushing the entire shoot . The most noticeable effect of MIS is a reduction in stem, leaf or petiole length invariably resulting in plants which are smaller and more compact than unstressed controls. However, the response of other variables can often differ between species and there may be either increases or decreases in stem or petiole diameter, root : shoot weight ratio, chlorophyll content or drought resistance . Why species should differ in this way, and what is the endogenous control mechanism for MIS responses, are unanswered questions . Ethylene, which increases as a result of MIS in several species may cause some MIS responses such as increased stem diameter, epinasty or a change in sex expression . However, evidence suggests that MIS retardation of extension growth may equally be due to lower or supraoptimal auxin levels or lower gibberellin levels .The uses in the field of the growth promoter gibberellin or the growth retardant chlormequat chloride (CCC) appear to be examples of respectively reversing or stimulating MIS growth response . MIS may be applied indoors if short compact plants are needed, either for aesthetic purposes as with floral crops, or if hardier and more manageable plants are needed, such as seedlings for transplanting in the field . Much more research is needed to estimate the importance of MIS in the field and to assess how such knowledge may be used to improve crop yield .

Mechanical Stimulation Modifies Canopy Architecture and Improves Volume Utilization Efficiency in Bell Pepper: Implications for Bioregenerative Life-support and Vertical Farming

“…It has long been recognized that mechanical stimulation (MS; stress), such as wind action, rubbing, constriction, shaking, and encounters with physical barriers can have a dramatic influence on plant morphological development (Biddington 1986, Darwin 1880, Jaffe 1973, Mitchell et al 1975, Mitchell 1977. Jaffe (1973) demonstrated that daily MS to partially mature internode tissue, applied by rubbing stem tissue between two fingers, could induce dramatic reductions in internode length resulting in dwarf phenotypes in a range of crop species.…”

“…Over the ensuing 40 years many others have followed up on Jaffe's work, notably amongst others, Cary Mitchell's group at Purdue (West Lafayette, IN, USA), Joyce Latimer at Virginia Tech (Blacksburg, VA, USA), and Janet Braam at Rice University (Houston, TX, USA). It is now known that thigmomorphogenesis includes a wide range of responses including, but not limited to, shortening of internodes, stem thickening, reduced leaf expansion, changes in chlorophyll content, and alterations in plant hormone levels (Beyl & Mitchell 1983, Biddington 1986, Braam 2005, Chehab et al 2008, Latimer et al 1991, Mitchell & Myers 1995, Monshausen & Haswell 2013. Abstract: Mechanical stimuli or stress has been shown to induce characteristic morphogenic responses (thigmomorphogenesis) in a range of crop species.…”

The Arabidopsis TCH4 Xyloglucan Endotransglycosylase (Substrate Specificity, pH Optimum, and Cold Tolerance)

“…11 5,1997 responses to environmental and hormonal stimuli through modification of the cell wall. For example, plants that are repeatedly touched generally grow shorter and stockier and may increase in strength and flexibility (for review, see Biddington, 1986;Jaffe and Forbes, 1993;Mitchell and Myers, 1995); these changes likely involve cell wall modifications. Auxin and brassinosteroid enhance growth; increased TCH4 expression may be an important step in hormone-induced alterations for cell expansion.…”

Actuation systems in plants as prototypes for bioinspired devices

“…Readers further interested in physiological aspects regarding stimulation and control are referred to some excellent reviews (Jaffe & Galston 1968;Roblin 1979;Satter & Galston 1981;Biddington 1986;Ueda & Yamamura 2000;Braam 2005;Telewski 2006). The first part of the paper provides an overview of the various mechanisms of movement at the macroscopic level by means of exemplary species that are well known for the actuation of their organs.…”