External Glands of Nepenthes Traps: Structure and Potential Function

Area of Science:

• Plant Biology
• Plant Anatomy
• Plant Physiology

Background:

• Nepenthes L. (tropical pitcher plants) are carnivorous plants with specialized pitcher traps.
• The outer pitcher surface features nectaries and various trichomes, including glandular types.
• Glandular trichomes in Nepenthes have complex structures with potential transport functions.

Purpose of the Study:

• To investigate the structure of glandular trichomes in Nepenthes bicalcarata and Nepenthes albomarginata.
• To determine the distribution of homogalacturonans (HGs) and hemicelluloses within the trichome cell walls.
• To elucidate the potential role of these trichomes in solute and water transport.

Main Methods:

• Light and electron microscopy were used to analyze trichome structures.
• Immunohistochemistry techniques employed antibodies against specific cell wall components (pectic homogalacturonans and hemicelluloses).
• Antibodies included JIM5, LM19, CCRC-M38, JIM7, LM20, LM5 for HGs, and LM25, LM15, CCRC-M138, LM10 for hemicelluloses.

Main Results:

• The presence of endodermal and transfer cells suggests active solute transport by peltate trichomes.
• Pectic homogalacturonans and hydrophilic hemicelluloses were identified in the trichome cell walls.
• These cell wall components indicate transport of water or aqueous solutions through the trichomes.

Conclusions:

• The glandular trichomes of Nepenthes possess structural and compositional features supporting active transport.
• The identified cell wall polysaccharides facilitate the movement of water and solutes.
• These findings suggest that Nepenthes trichomes function as hydathodes or hydropotes, contributing to plant physiology.