Investigating the rheological properties of native plant latex

Abstract

Plant latex, the source of natural rubber, has been of interest to mankind for millennia, with much of the research on its rheological (flow) properties focused towards industrial application. However, little is known regarding the rheology of the native material as produced by the plant, a key factor in determining latex's biological functions. In this study, we outline a method for rheological comparison between native latices that requires a minimum of preparatory steps. Our approach provides quantitative insights into the coagulation mechanisms of Euphorbia and Ficus latex allowing interpretation within a comparative evolutionary framework. Our findings reveal that in laboratory conditions both latices behave like non-Newtonian materials with the coagulation of Euphorbia latex being mediated by a slow evaporative process (more than 60 min), whereas Ficus appears to use additional biochemical components to increase the rate of coagulation (more than 30 min). Based on these results, we propose two different primary defensive roles for latex in these plants: the delivery of anti-herbivory compounds (Euphorbia) and rapid wound healing (Ficus).

Rheological Properties of Polymer Colloid–Cellulose Thickener Systems

“…Shear rate of the system 2 is also up to 660 s -1 but it starts to yield at 18.8 Pa that is confirmed by the results of the structural and mechanical analysis (the system is classified as the II type). Occurrence of hysteresis in the systems at forward and backward movement confirms formation of the coagulate structures [22]. Table 1 The systems are thixotropic liquids.…”

“…To obtain easy-to-layer paintwork materials it is rational to account properties of the systems at a wide range of shear rate [22][23][24]. Whole rheological curves that depict dependence between shear stress and shear rate (Fig.…”

Characterisation of general proteolytic, milk clotting and antifungal activity of Ficus carica latex during fruit ripening

“…Mechanical protection relies on the ability of latex to coagulate at the site of injury, which is attributed to the presence of cis ‐1,4‐polyisoprene, commonly known as rubber. Biochemical protection relies on the physiological action of active compounds …”

“…3 One of the most important physiological roles of latex is protection from pathogen invasion throughout the injured tissue. 4 Younger parts of the fig tree contain the largest volumes of latex (young shoots, pedicles and leaves), since latex represents their only mechanism of protection. Older parts of the plant have many additional protection strategies, e.g.…”

“…Biochemical protection relies on the physiological action of active compounds. 4 Latex is a complex mixture of many different types of secondary metabolites and proteins which differ between species and enable them to have specific protection strategies. Some of them are alkaloids, terpenoids, tannins, sterols, 5 polyphenols, 6 as well as proteins, e.g.…”