Adhesive root hairs facilitate Posidonia oceanica seedling settlement on rocky substrates

• DOI: 10.7287/peerj.preprints.1149v1
• Publication Date: 2018-01-12T16:41:51Z
• Authors: Adriana Alagna; Tomás Vega Fernández; Giovanni D'Anna; Silvio Fici; Carlo Magliola; Fabio Badalamenti
• Keywords: Posidonia oceanica; Root hair

Posidonia oceanica , the dominant Mediterranean seagrass, has been historically described as a species typically growing on mobile substrates whose development requires precursor communities. During more than 10 years of direct observations, we noticed that P. seedlings were often firmly anchored to rocky reefs, even at exposed sites. Thus, analysed ultrastructural features seedling root systems identify specific traits may represent adaptations for early anchorage bottoms. Subapical sections adventitious roots obtained from 2-3 months old specimens collected in field and observed SEM revealing an extensive coverage adhesive hairs with maximum length 2400 µm. Hairs provided enlarged tips width 78.3 µm, which extended contact area between hair tip substrate. To test whether facilitate establishment substrates, manipulative experiment was performed. 360 reared 5 land-based culture facility under simulated natural hydrodynamic conditions suitable anchorage. Two main substrate investigated: firmness (i.e., sand vs. rock) complexity size interstitial spaces rocks). Anchorage strongly influenced by occurred only rocks through adhesion sticky hairs. Percentage high 89%. The minimum force required dislodge plantlets attached reached 23.8 N, would potentially allow many overcome winter storms field. ability retain increased their complexity. appropriate microsites settlement, seeds successfully retained available. Adhesive allowed fast strong consolidated when system not yet developed. This mechanism could favour plant recruitment respect ones, contrast traditional paradigms. Such adaptation leads hypothesize new microsite driven bottleneck survival linked features.