RESEARCH ARTICLE Understanding the sexual recruitment of one of the oldest and largest organisms on Earth, the seagrass Posidonia oceanica 1☯ 2☯ 1☯ Laura Guerrero-MeseguerID *, Carlos Sanz-LaÂzaro , Arnaldo MarõÂn 1 Departamento de EcologõÂa e HidrologõÂa. Facultad de BiologõÂa, Universidad de Murcia, Campus de Espinardo, Murcia, Spain, 2 Departamento de EcologõÂa, PabelloÂn 13, Universidad de Alicante, Alicante, Spain ☯ These authors contributed equally to this work. *
[email protected] a1111111111 Abstract a1111111111 a1111111111 The seagrass Posidonia oceanica is considered one of the oldest and largest living organ- a1111111111 isms on Earth. Notwithstanding, given the difficulty of monitoring its fruits and seeds in the a1111111111 field, the development of P. oceanica during its sexual recruitment is not completely under- stood. We studied the stages of development of P. oceanica seeds from their dispersion in the fruit interior to their settlement in sediment through histological, ultrastructural and meso- cosm experiments. P. oceanica sexual recruitment can be divided into three main stages OPEN ACCESS that focus on maximising photosynthesis and anchoring the seedlings to the sediment. In Citation: Guerrero-Meseguer L, Sanz-LaÂzaro C, the first stage (fruit dispersion), seeds perform photosynthesis while being transported MarõÂn A (2018) Understanding the sexual recruitment of one of the oldest and largest inside the fruit along the sea surface. In the second stage (seed adhesion), seeds develop organisms on Earth, the seagrass Posidonia adhesive microscopic hairs that cover the primary and secondary roots and favour seed oceanica. PLoS ONE 13(11): e0207345. https://doi. adhesion to the substrate. In the last stage (seedling anchorage), roots attach the seedlings org/10.1371/journal.pone.0207345 to the substrate by orienting them towards the direction of light to maximise photosynthesis.