VA MYCORRHIZAE IN STRAND VEGETATION OF HAWAII: EVIDENCE FOR LONG-DISTANCE CODISPERSAL OF PLANTS AND FUNGI

Area of Science:

• Ecology
• Mycology
• Botany

Background:

• Vesicular-arbuscular mycorrhizal fungi (VAMF) are crucial symbionts for plant survival, especially in nutrient-limited ecosystems.
• The coastal strand environment of the Hawaiian Islands presents unique challenges for plant life due to nutrient scarcity and salinity.

Purpose of the Study:

• To investigate the presence and distribution of VAMF in the coastal strand ecosystem of the Hawaiian Islands.
• To determine the relationship between VAMF colonization and plant species origin (endemic, indigenous, alien).
• To explore the potential for codispersal of VAMF and vascular plants as a mechanism for maintaining mycorrhizal symbiosis.

Main Methods:

• Surveying VAMF presence in beach sand, driftline debris, and roots of 31 vascular plant species.
• Assessing VAMF colonization intensity in relation to plant species origin.
• Conducting pot-culture studies using plant roots as inocula for VAMF.

Main Results:

• VAMF were found in 23 of 31 examined plant species and associated with native rhizomes.
• Mycorrhizal colonization was most frequent and intense in endemic plants, followed by indigenous, and then alien species.
• Plant roots, even those exposed to seawater, served as effective inocula for VAMF in pot cultures.

Conclusions:

• A close association exists between VAMF propagules and vegetative plant fragments, suggesting codispersal.
• Codispersal of VAMF and plants likely ensures the maintenance of this vital symbiosis in nutrient-deficient coastal habitats.
• This mechanism helps explain the high prevalence of mycotrophy among tropical Pacific strand plant species.