Stromules: Recent Insights into a Long Neglected Feature of Plastid Morphology and Function

Hanson, Maureen R.; Sattarzadeh, Amirali

doi:10.1104/pp.110.170852

Cited by 87 publications

(83 citation statements)

References 43 publications

(65 reference statements)

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“…2007a; Holzinger et al . 2007a; Sage & Sage 2009; Lütz 2010; Hanson & Sattarzadeh 2011; Lütz et al . 2012).…”

Section: Discussionunclassified

“…The extensions were termed ‘stromules’ and defined as stroma‐filled tubular extensions that appear to be less than 0.8 μ m in diameter (Köhler & Hanson 2000). The function of stromules is still under discussion, especially regarding the exchange of metabolites and proteins (Hanson & Sattarzadeh 2011, 2013; Schattat et al . 2012, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Chloroplast protrusions in leaves of Ranunculus glacialis L. respond significantly to different ambient conditions, but are not related to temperature stress

Moser

Holzinger

Buchner

2015

Plant Cell & Environment

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The occurrence of chloroplast protrusions (CPs) in leaves of R anunculus glacialis L. in response to different environmental conditions was assessed. CPs occur highly dynamically. They do not contain thylakoids and their physiological function is still largely unknown. Controlled in situ sampling showed that CP formation follows a pronounced diurnal rhythm. Between 2 and 27 °C the relative proportion of chloroplasts with CPs (rCP) showed a significant positive correlation to leaf temperature (TL; 0.793, P < 0.01), while irradiation intensity had a minor effect on rCP. In situ shading and controlled laboratory experiments confirmed the significant influence of TL. Under moderate irradiation intensity, an increase of TL up to 25 °C significantly promoted CP formation, while a further increase to 37 °C led to a decrease. Furthermore, rCP values were lower in darkness and under high irradiation intensity. Gas treatment at 2000 ppm /2% led to a significant decrease of rCP, suggesting a possible involvement of photorespiration in CP formation. Our findings demonstrate that in R . glacialis, CPs are neither a rare phenomenon nor a result of heat or light stress; on the contrary, they seem to be most abundant under moderate temperature and non‐stress irradiation conditions.

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“…2007a; Holzinger et al . 2007a; Sage & Sage 2009; Lütz 2010; Hanson & Sattarzadeh 2011; Lütz et al . 2012).…”

Section: Discussionunclassified

Section: Introductionmentioning

confidence: 99%

Chloroplast protrusions in leaves of Ranunculus glacialis L. respond significantly to different ambient conditions, but are not related to temperature stress

Moser

Holzinger

Buchner

2015

Plant Cell & Environment

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“…With the finding that signals originating within the chloroplast can trigger stromule formation, we then explored whether stromule formation is dependent on cytosolic structures (e.g., the cytoskeleton), as has been suggested previously (10,15), or if chloroplasts can make stromules on their own. Previous studies have argued that stromule formation is guided and supported by the cytoskeleton and endoplasmic reticulum, but whether stromule formation requires these external factors is unknown (10,30). To address this question, we extracted chloroplasts from leaves of N. benthamiana, A. thaliana, and Spinacia oleracea using well-established methods for isolating functional, undamaged chloroplasts (31).…”

Section: Nadph-dependent Thioredoxin Reductase C Regulates Chloroplastmentioning

confidence: 99%

“…Visualizing stromules by transmission electron microscopy is challenging, because stromule membranes are not easily distinguished from other membranes in thin sections required for conventional electron microscopy. We used 3D structured illumination microscopy (3D-SIM) to obtain the highest-resolution images of wild-type stromules to date (10,33), and present some representative examples in Fig. 4 and Movie S3.…”

Section: Nadph-dependent Thioredoxin Reductase C Regulates Chloroplastmentioning

confidence: 99%

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Chloroplasts extend stromules independently and in response to internal redox signals

Brunkard

Runkel

Zambryski

2015

Proc. Natl. Acad. Sci. U.S.A.

146

145

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A fundamental mystery of plant cell biology is the occurrence of "stromules," stroma-filled tubular extensions from plastids (such as chloroplasts) that are universally observed in plants but whose functions are, in effect, completely unknown. One prevalent hypothesis is that stromules exchange signals or metabolites between plastids and other subcellular compartments, and that stromules are induced during stress. Until now, no signaling mechanisms originating within the plastid have been identified that regulate stromule activity, a critical missing link in this hypothesis. Using confocal and superresolution 3D microscopy, we have shown that stromules form in response to light-sensitive redox signals within the chloroplast. Stromule frequency increased during the day or after treatment with chemicals that produce reactive oxygen species specifically in the chloroplast. Silencing expression of the chloroplast NADPH-dependent thioredoxin reductase, a central hub in chloroplast redox signaling pathways, increased chloroplast stromule frequency, whereas silencing expression of nuclear genes related to plastid genome expression and tetrapyrrole biosynthesis had no impact on stromules. Leucoplasts, which are not photosynthetic, also made more stromules in the daytime. Leucoplasts did not respond to the same redox signaling pathway but instead increased stromule formation when exposed to sucrose, a major product of photosynthesis, although sucrose has no impact on chloroplast stromule frequency. Thus, different types of plastids make stromules in response to distinct signals. Finally, isolated chloroplasts could make stromules independently after extraction from the cytoplasm, suggesting that chloroplast-associated factors are sufficient to generate stromules. These discoveries demonstrate that chloroplasts are remarkably autonomous organelles that alter their stromule frequency in reaction to internal signal transduction pathways.chloroplasts | stromules | redox signaling | light signaling | leucoplasts

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When One Genome Is Not Enough: Organellar Heteroplasmy in Plants

Ramsey

Mandel

2019

Annual Plant Reviews Online

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Heteroplasmy occurs when copies of an organellar genome (plastid or mitochondrial) differ from one another either within a cell or among cells within an individual. This phenomenon was first discovered in plastids over 100 years ago, though ‘heteroplasmy’ was not formally defined until decades later. Mitochondrial and plastid heteroplasmy have since been discovered in diverse taxa, including numerous plants, particularly those with the gynodioecious breeding system. Though heteroplasmy can arise through mutations in organellar genomes, biparental inheritance of organelles often generates heteroplasmy. This article is intended to summarise the cytoploid nature of organellar genomes and different aspects of mitochondrial and plastid heteroplasmy, from its discovery, to the development of detection methods. We will also discuss the effects of heteroplasmy on individuals, populations, and species, with regard to fitness, cytonuclear interactions, and genome evolution. Finally, we highlight a few research questions which we consider in need of further investigation to understand the prevalence and effects of heteroplasmy in natural settings.

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Stromules: Recent Insights into a Long Neglected Feature of Plastid Morphology and Function

Cited by 87 publications

References 43 publications

Chloroplast protrusions in leaves of Ranunculus glacialis L. respond significantly to different ambient conditions, but are not related to temperature stress

Chloroplast protrusions in leaves of Ranunculus glacialis L. respond significantly to different ambient conditions, but are not related to temperature stress

Chloroplasts extend stromules independently and in response to internal redox signals

When One Genome Is Not Enough: Organellar Heteroplasmy in Plants

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