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ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture

In Arabidopsis, the actin gene family comprises eight expressed and two non-expressed ACTIN (ACT) genes. Of the eight expressed isoforms, ACT2, ACT7, and ACT8 are differentially expressed in vegetative tissues and may perform specific roles in development. Using tobacco mesophyll protoplasts, we pre...

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Autores principales: Sheahan, Michael B., Collings, David A., Rose, Ray J., McCurdy, David W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076399/
https://www.ncbi.nlm.nih.gov/pubmed/32050601
http://dx.doi.org/10.3390/plants9020225
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author Sheahan, Michael B.
Collings, David A.
Rose, Ray J.
McCurdy, David W.
author_facet Sheahan, Michael B.
Collings, David A.
Rose, Ray J.
McCurdy, David W.
author_sort Sheahan, Michael B.
collection PubMed
description In Arabidopsis, the actin gene family comprises eight expressed and two non-expressed ACTIN (ACT) genes. Of the eight expressed isoforms, ACT2, ACT7, and ACT8 are differentially expressed in vegetative tissues and may perform specific roles in development. Using tobacco mesophyll protoplasts, we previously demonstrated that actin-dependent clustering of chloroplasts around the nucleus prior to cell division ensures unbiased chloroplast inheritance. Here, we report that actin-dependent chloroplast clustering in Arabidopsis mesophyll protoplasts is defective in act7 mutants, but not act2-1 or act8-2. ACT7 expression was upregulated during protoplast culture whereas ACT2 and ACT8 expression did not substantially change. In act2-1, ACT7 expression increased in response to loss of ACT2, whereas in act7-1, neither ACT2 nor ACT8 expression changed appreciably in response to the absence of ACT7. Semi-quantitative immunoblotting revealed increased actin concentrations during culture, although total actin in act7-1 was only two-thirds that of wild-type or act2-1 after 96 h culture. Over-expression of ACT2 and ACT8 under control of ACT7 regulatory sequences restored normal levels of chloroplast clustering. These results are consistent with a requirement for ACT7 in actin-dependent chloroplast clustering due to reduced levels of actin protein and gene induction in act7 mutants, rather than strong functional specialization of the ACT7 isoform.
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spelling pubmed-70763992020-03-24 ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture Sheahan, Michael B. Collings, David A. Rose, Ray J. McCurdy, David W. Plants (Basel) Article In Arabidopsis, the actin gene family comprises eight expressed and two non-expressed ACTIN (ACT) genes. Of the eight expressed isoforms, ACT2, ACT7, and ACT8 are differentially expressed in vegetative tissues and may perform specific roles in development. Using tobacco mesophyll protoplasts, we previously demonstrated that actin-dependent clustering of chloroplasts around the nucleus prior to cell division ensures unbiased chloroplast inheritance. Here, we report that actin-dependent chloroplast clustering in Arabidopsis mesophyll protoplasts is defective in act7 mutants, but not act2-1 or act8-2. ACT7 expression was upregulated during protoplast culture whereas ACT2 and ACT8 expression did not substantially change. In act2-1, ACT7 expression increased in response to loss of ACT2, whereas in act7-1, neither ACT2 nor ACT8 expression changed appreciably in response to the absence of ACT7. Semi-quantitative immunoblotting revealed increased actin concentrations during culture, although total actin in act7-1 was only two-thirds that of wild-type or act2-1 after 96 h culture. Over-expression of ACT2 and ACT8 under control of ACT7 regulatory sequences restored normal levels of chloroplast clustering. These results are consistent with a requirement for ACT7 in actin-dependent chloroplast clustering due to reduced levels of actin protein and gene induction in act7 mutants, rather than strong functional specialization of the ACT7 isoform. MDPI 2020-02-10 /pmc/articles/PMC7076399/ /pubmed/32050601 http://dx.doi.org/10.3390/plants9020225 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sheahan, Michael B.
Collings, David A.
Rose, Ray J.
McCurdy, David W.
ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title_full ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title_fullStr ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title_full_unstemmed ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title_short ACTIN7 Is Required for Perinuclear Clustering of Chloroplasts during Arabidopsis Protoplast Culture
title_sort actin7 is required for perinuclear clustering of chloroplasts during arabidopsis protoplast culture
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076399/
https://www.ncbi.nlm.nih.gov/pubmed/32050601
http://dx.doi.org/10.3390/plants9020225
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AT mccurdydavidw actin7isrequiredforperinuclearclusteringofchloroplastsduringarabidopsisprotoplastculture