Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>

In the marine red alga <i>Pyropia yezoensis</i>, filamentous phases of the life cycle, e.g., the conchocelis (sporophyte) and conchosporangium (conchosporophyte), proliferate by tip growth. In this study, we investigated the possible involvement of phosphoinositide turnover and actin pol...

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Main Authors: Ryunosuke Irie, Koji Mikami
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/14/2194
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author Ryunosuke Irie
Koji Mikami
author_facet Ryunosuke Irie
Koji Mikami
author_sort Ryunosuke Irie
collection DOAJ
description In the marine red alga <i>Pyropia yezoensis</i>, filamentous phases of the life cycle, e.g., the conchocelis (sporophyte) and conchosporangium (conchosporophyte), proliferate by tip growth. In this study, we investigated the possible involvement of phosphoinositide turnover and actin polymerization in the spontaneous initiation and tip growth of new branches in isolated single-celled conchocelis cells using pharmacological treatments. Treatment with LY294002 and U73122, specific inhibitors of phosphoinositide-phosphate 3-kinase and phospholipase C, respectively, reduced side-branch formation and inhibited the elongation of branches. In addition, two inhibitors of the actin cytoskeleton, cytochalasin B (CCB) and latrunculin B (LAT-B), had similar effects on tip growth. However, CCB did not alter the branching rate of single-celled conchocelis, whereas LAT-B did. As CCB and LAT-B affect actin polymerization through different mechanisms, this result suggests differences in the contributions of actin polymerization to branch initiation versus tip growth. These findings demonstrate the critical and diverse functional roles played by phosphoinositide turnover and actin polymerization in the regulation of the initiation and maintenance of tip growth in the conchocelis phase of <i>P. yezoensis</i>.
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spelling doaj-art-6abbfd21fe3b4bf9a6ce494bd7eccb0c2025-08-20T03:08:06ZengMDPI AGPlants2223-77472025-07-011414219410.3390/plants14142194Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>Ryunosuke Irie0Koji Mikami1Fisheries Promotion Division, Agriculture, Forestry and Fisheries Department, Oita Prefectural Government, 3-1-1 Otemachi, Oita 870-8501, JapanDepartment of Integrative Studies of Plant and Animal Production, School of Food Industrial Sciences, Miyagi University, 2-2-1 Hatatate, Taihaku-ku, Sendai 982-0215, JapanIn the marine red alga <i>Pyropia yezoensis</i>, filamentous phases of the life cycle, e.g., the conchocelis (sporophyte) and conchosporangium (conchosporophyte), proliferate by tip growth. In this study, we investigated the possible involvement of phosphoinositide turnover and actin polymerization in the spontaneous initiation and tip growth of new branches in isolated single-celled conchocelis cells using pharmacological treatments. Treatment with LY294002 and U73122, specific inhibitors of phosphoinositide-phosphate 3-kinase and phospholipase C, respectively, reduced side-branch formation and inhibited the elongation of branches. In addition, two inhibitors of the actin cytoskeleton, cytochalasin B (CCB) and latrunculin B (LAT-B), had similar effects on tip growth. However, CCB did not alter the branching rate of single-celled conchocelis, whereas LAT-B did. As CCB and LAT-B affect actin polymerization through different mechanisms, this result suggests differences in the contributions of actin polymerization to branch initiation versus tip growth. These findings demonstrate the critical and diverse functional roles played by phosphoinositide turnover and actin polymerization in the regulation of the initiation and maintenance of tip growth in the conchocelis phase of <i>P. yezoensis</i>.https://www.mdpi.com/2223-7747/14/14/2194tip growthbranch formationstem cellactin polymerizationphosphoinositide-phosphate 3-kinasephospholipase C
spellingShingle Ryunosuke Irie
Koji Mikami
Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
Plants
tip growth
branch formation
stem cell
actin polymerization
phosphoinositide-phosphate 3-kinase
phospholipase C
title Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
title_full Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
title_fullStr Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
title_full_unstemmed Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
title_short Phosphoinositide Signaling and Actin Polymerization Are Critical for Tip Growth in the Marine Red Alga <i>Pyropia yezoensis</i>
title_sort phosphoinositide signaling and actin polymerization are critical for tip growth in the marine red alga i pyropia yezoensis i
topic tip growth
branch formation
stem cell
actin polymerization
phosphoinositide-phosphate 3-kinase
phospholipase C
url https://www.mdpi.com/2223-7747/14/14/2194
work_keys_str_mv AT ryunosukeirie phosphoinositidesignalingandactinpolymerizationarecriticalfortipgrowthinthemarineredalgaipyropiayezoensisi
AT kojimikami phosphoinositidesignalingandactinpolymerizationarecriticalfortipgrowthinthemarineredalgaipyropiayezoensisi