Stromule extension along microtubules coordinated with actin-mediated anchoring guides perinuclear chloroplast movement during innate immunity

• Published in: eLife Vol. 7
• Main Authors: Kumar, Amutha Sampath, Park, Eunsook, Nedo, Alexander, Alqarni, Ali, Ren, Li, Hoban, Kyle, Modla, Shannon, McDonald, John H, Kambhamettu, Chandra, Dinesh-Kumar, Savithramma P, Caplan, Jeffrey Lewis
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 17.01.2018; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Actin; Actins - metabolism; Analysis; Cell Biology; Chloroplasts; Chloroplasts - metabolism; cytoskeleton; Epidermal Cells - metabolism; Filaments; Immune response; Immunity, Innate; Innate immunity; Medical research; Microtubules; Microtubules - metabolism; Morphology; Motility; Movement; Muscle proteins; Nicotiana; Nicotiana benthamiana; Nuclei; organelle movement; Parks; Photosynthesis; Plant biochemistry; Plant Biology; Plant Epidermis - cytology; Plant Epidermis - immunology; plant innate immunity; Proteins; Scientists; Soil sciences; Statistical analysis; stromules; Transmission electron microscopy; Viral proteins; United States > US; California; organelle movement; Nicotiana benthamiana; cell biology; cytoskeleton; plant innate immunity; chloroplasts; plant biology; stromules
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.23625

Dynamic tubular extensions from chloroplasts called stromules have recently been shown to connect with nuclei and function during innate immunity. We demonstrate that stromules extend along microtubules (MTs) and MT organization directly affects stromule dynamics since stabilization of MTs chemically or genetically increases stromule numbers and length. Although actin filaments (AFs) are not required for stromule extension, they provide anchor points for stromules. Interestingly, there is a strong correlation between the direction of stromules from chloroplasts and the direction of chloroplast movement. Stromule-directed chloroplast movement was observed in steady-state conditions without immune induction, suggesting it is a general function of stromules in epidermal cells. Our results show that MTs and AFs may facilitate perinuclear clustering of chloroplasts during an innate immune response. We propose a model in which stromules extend along MTs and connect to AF anchor points surrounding nuclei, facilitating stromule-directed movement of chloroplasts to nuclei during innate immunity.