Exploring silica accumulation in bamboo leaves: A study on phytolith morphology and epidermal patterning in the tropical giant bamboo Dendrocalamus copelandii.

Background And Aims: Bamboo is a grass in the Poaceae family with various applications. Bamboo leaves can accumulate high silica. However, silica deposition in bamboo has received limited study. Therefore, this research investigated silica accumulation in Dendrocalamus copelandii leaves. The study includes the localisation of silica through phytolith morphology, examination of the distribution patterns of phytoliths in epidermal tissues, analysis of silica accumulation within specialised silica cells (short cells), and analysis of silicon concentration across various leaf developmental stages.

Methods: We employed imaging techniques, including Differential interference contrast and Scanning electron microscope incorporated with an energy-dispersive X-ray spectrometer, to investigate silica accumulation in bamboo leaves. We also analysed silicon concentration using Inductively coupled plasma-optical emission spectroscopy.

Key Results: Leaves of D. copelandii exhibited 11 phytolith morphotypes, such as BILOBATE, POLYLOBATE, SADDLE, ACUTE, ACUTE BULBOSUS, MICROHAIR, STOMATA, BULLIFORM FLABELLATE, ELONGATE SINUATE, ELONGATE ENTIRE and TRACHEARY. Most of these phytoliths were found in short cells (BILOBATE, POLYLOBATE and SADDLE) of epidermal tissues. The short cells were arranged transversely along the leaf length. BILOBATE was found in both the abaxial and adaxial epidermis, while SADDLE was found only in the abaxial epidermis. Silica accumulation in the short cells of unexpanded leaves begins at the leaf apex, spreads to the middle and base positions, and accumulates first in the abaxial before the adaxial epidermis. Moreover, bamboo leaves accumulate more silicon concentration as they age.

Conclusions: Phytolith morphotypes and silica accumulation in epidermal short cells are key factors in understanding silica deposition. Leaf age and climate significantly impact silicon concentration in bamboo leaves. Our findings are informative for archaeological studies and for plant taxonomical classification. The results are also applicable for biotechnological applications.