Sessile Trichomes Play Major Roles in Prey Digestion and Absorption, While Stalked Trichomes Function in Prey Predation in Byblis guehoi

Abstract

Carnivorous plants in the genus Byblis obtain nutrients by secreting viscous glue drops and enzymes that trap and digest small organisms. Here, we used B. guehoi to test the long-held theory that different trichomes play different roles in carnivorous plants. In the leaves of B. guehoi, we observed a 1:2.5:14 ratio of long-stalked, short-stalked, and sessile trichomes. We demonstrated that the stalked trichomes play major roles in the production of glue droplets, while the sessile trichomes secrete digestive enzymes, namely proteases and phosphatases. In addition to absorbing digested small molecules via channels/transporters, several carnivorous plants employ a more efficient system: endocytosis of large protein molecules. By feeding B. guehoi fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) to monitor protein transport, we found that sessile trichomes exhibited more endocytosis than long- and short-stalked trichomes. The uptaken FITC-BSA was delivered to the neighboring short epidermal cells in the same row as the sessile trichomes, then to the underlying mesophyll cells; however, no signals were detected in the parallel rows of long epidermis cells. The FITC control could be taken up by sessile trichomes but not transported out. Our study shows that B. guehoi has developed a well-organized system to maximize its food supply, consisting of stalked trichomes for prey predation and sessile trichomes for prey digestion. Moreover, the finding that sessile trichomes transfer large, endocytosed protein molecules to the underlying mesophyll, and putatively to the vascular tissues, but not laterally to the terminally differentiated epidermis, indicates that the nutrient transport system has evolved to maximize efficiency.

Is the co-option of jasmonate signalling for botanical carnivory a universal trait for all carnivorous plants?

“…Due to their rarity, two genera of carnivorous plants within Lamiales with an independent origin of carnivory, Byblis and Philcoxia , remain also a totally unexplored group of carnivorous plants in regard to digestive physiology. It was suggested that Byblis resembles Roridula and relies on digestive mutualisms ( Ellis and Midgley 1996 ), but Li et al . (2023) recently documented protease activity in Byblis guehoi , which makes Byblis an interesting object for further investigation.…”

Do Cuticular Gaps Make It Possible to Study the Composition of the Cell Walls in the Glands of Drosophyllum lusitanicum?

“…Cuticle discontinuities in carnivorous plant glands are easily detected using vital dyes, e.g., an aqueous solution of neutral red or methylene blue [24,31,36,37,40]. Moreover, these cuticle discontinuities in carnivorous plant glands allow intact cells to be penetrated by dyes such as DiOC 6 and styryl dye FM4-64, thereby making it possible to visualize the organelles and membranes, as was shown by Płachno et al [41], Lichtscheidl et al [44], and Li et al [45]. Thus, these cuticle discontinuities make the cells of the carnivorous plant glands an excellent research model.…”