What does the quantitative morphological diversity of starch grains in terrestrial orchids indicate?

Abstract

Starches granules vary in structure and morphologies in the orchids as well as other plant sources that starch is industrially valuable. This article aims to provide information on the variability of starch grain based on quantitative size and shape descriptive features using regression and discriminant analysis and to develop an easy method related to starch morphology giving perspective for various disciplines. All measurements of 26 species belonging to three different tribes were obtained using polarized light and scanning electron microscopy. Results show significant differences in size descriptive (e.g., perimeter, the major axis of the fit ellipse, minimum caliper diameter) and shape descriptive (e.g., circularity, hilum position) features, suggesting that taxonomic assignment of orchids starch granules to a higher category could enable to the testing of the industrially desired product and protect orchid biodiversity. Highlights• Studies on detailed morphology and morphometry of orchid starch using polarized light microscopy and scanning electron microscopy.• Relation and effect of size descriptive on shape descriptive features (circularity and hilum position) of the starch grains.• Described size and shape pattern of starch granules, and confirmed the usefulness of quantitative data sets for easily and effectively assessing the variation of the orchid.

Anatomy and Histochemistry of the Vegetative System of Brachystele guayanensis (Lindl.) Schltr. (Orchidaceae), a Potential Medicinal Species

“…While it is not entirely clear, some authors [ 33 , 34 ] attribute the polyhedral form of spiranthosomes to intracellular density. However, others believe that such structures reflect shared genetic factors and phylogenetic characters [ 35 ]. Furthermore, we believe that the presence of membranes surrounding the tiny starch grains possibly regulates the hydrolysis process, as well as the availability of sugars for the symbiotic fungi.…”

Anatomy and Histochemistry of the Vegetative Organs of Brachystele guayanensis (Lindl.) Schltr. (Orchidaceae), a Potential Medicinal Species

“…These characters are frequently observed in Orchidoideae [e.g., 11, 15, 16], with terrestrial members of the family (as was observed in the species studied here) generally having thick, fleshy roots with a more expressive cortex (in terms the numbers of layers) that is responsible for holding reserves of water, starch grains, and other nutrients, with a less expressive velamen. Some of the cells in the cortical parenchyma contain raphides (Figure 4e), as observed in different groups of Monocotyledons [e.g., 34], with polyhedral starch grains gathered in spiranthosomes (Figure 4f) -spherical specialized amyloplasts found in Cranichideae and interpreted as a synapomorphy of the tribe [ See 5,17,40,41].…”

Traditional, Therapeutic Uses and Phytochemistry of Terrestrial European Orchids and Implications for Conservation

“…These two species in particular (and a few others as well, i.e., Goodyera repens (L.) R.Br., Orchis mascula ), being also present in the folk traditions and pharmacopoeia of other extra-EU countries, have therefore been studied by non-European working groups. Finally, starch [ 173 ], ash, sugar, sucrose [ 13 ], and glucomannan [ 38 , 84 ] were detected in orchid tubers.…”