Mineral Deposits in Ficus Leaves: Morphologies and Locations in Relation to Function

Abstract

trees are adapted to diverse environments and have some of the highest rates of photosynthesis among trees. leaves can deposit one or more of the three major mineral types found in leaves: amorphous calcium carbonate cystoliths, calcium oxalates, and silica phytoliths. In order to better understand the functions of these minerals and the control that the leaf exerts over mineral deposition, we investigated leaves from 10 species from vastly different environments (Rehovot, Israel; Bologna, Italy; Issa Valley, Tanzania; and Ngogo, Uganda). We identified the mineral locations in the soft tissues, the relative distributions of the minerals, and mineral volume contents using microcomputed tomography. Each species is characterized by a unique 3D mineral distribution that is preserved in different environments. The mineral distribution patterns are generally different on the adaxial and abaxial sides of the leaf. All species examined have abundant calcium oxalate deposits around the veins. We used micromodulated fluorimetry to examine the effect of cystoliths on photosynthetic efficiency in two species having cystoliths abaxially and adaxially () or only abaxially (). In , both adaxial and abaxial cystoliths efficiently contributed to light redistribution inside the leaf and, hence, increased photosynthetic efficiency, whereas in, the abaxial cystoliths did not increase photosynthetic efficiency.

Cystoliths inFicusleaves: increasing carbon fixation in saturating light by light scattering off a mineral substrate

“…Measurements were performed on freshly sampled leaves, immediately after detachment. To perform leaf auto-fluorescence measurements a micro-fluorimeter setup was custom built around a commercial microscope (Eclipse Ti-U, Nikon) as in Pierantoni et al (2018). A 635 nm pulsed diode laser (EPL635, Edinburgh Instruments) emitting pulses with a 100ps duration at a 20 MHz repetition rate excited the chlorophyll in the leaf.…”

“…S1). Data for F. microcarpa and F. carica were taken from Pierantoni et al (2018). The data were recorded and analyzed with a custom written MATLAB script.…”

“…In fact, although the upper, palisade tissue, is more efficient in light absorption than the lower, spongy tissue, the latter has higher light absorption per unit photosynthetic pigments (Xiao et al 2016). However, a major difficulty for the leaf to efficiently use the incident photons on both surfaces is that the uppermost layer of cells absorbs almost all the light, creating a steep light gradient from the leaf surface to the leaf interior (Vogelmann 1993, Vogelman et al 1996, Zhu et al 2010, Pierantoni et al 2018). Thus, under most irradiance regimes the impinging light exceeds the saturation threshold (Vogelmann et al 1989, Ort 2001, Sušila et al 2004).…”

“…Notably, both of these properties were found to be highly correlated with one another, reporting on the wasted portion of absorbed light and therefore serving as an inverse proxy for the efficiency of photosynthesis (Govindjee 1986, Papageorgiou 2007). Measurement of chlorophyll fluorescence has the advantage of accessing local differences in fluorescence with micrometer resolution, and was used in two follow-up studies on various Ficus species (Pierantoni et al 2017, 2018). Microfluorimetry can thus be used to differentiate between the effects of irradiance on minerals and on the surrounding tissue.…”

Future Perspectives on Biological Fabrication and Material Farming

“…Biological mineralization is also a biological fabrication process by animals (e.g., bones, shells, spicules) [48,49] and plants (e.g., phytoliths, cystoliths). [50,51] Biominerals are composed of one inorganic part (the mineral) and the organic part that fulfill numerous biological purposes (and evolutionary advantageous) with superior and improved properties (e.g., mechanical and/ or light guiding) when compared with their pure inorganic counterparts (nacre, deep sea sponges, and light guiding properties). [52][53][54] I can envision the exploitation of biomineralizing Small Methods 2019, 3, 1800136 Figure 2.…”