title: Entire Photodamaged Chloroplasts Are Transported to the Central Vacuole by Autophagy.
abstract: Turnover of dysfunctional organelles is vital to maintain homeostasis in eukaryotic cells. As photosynthetic organelles, plant chloroplasts can suffer sunlight-induced damage. However, the process for turnover of entire damaged chloroplasts remains unclear. Here, we demonstrate that autophagy is responsible for the elimination of sunlight-damaged, collapsed chloroplasts inArabidopsis thalianaWe found that vacuolar transport of entire chloroplasts, termed chlorophagy, was induced by UV-B damage to the chloroplast apparatus. This transport did not occur in autophagy-defectiveatgmutants, which exhibited UV-B-sensitive phenotypes and accumulated collapsed chloroplasts. Use of a fluorescent protein marker of the autophagosomal membrane allowed us to image autophagosome-mediated transport of entire chloroplasts to the central vacuole. In contrast to sugar starvation, which preferentially induced distinct type of chloroplast-targeted autophagy that transports a part of stroma via the Rubisco-containing body (RCB) pathway, photooxidative damage induced chlorophagy without prior activation of RCB production. We further showed that chlorophagy is induced by chloroplast damage caused by either artificial visible light or natural sunlight. Thus, this report establishes that an autophagic process eliminates entire chloroplasts in response to light-induced damage.
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 980-8578 Sendai, Japan m-izumi@ige.tohoku.ac.jp.|Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 980-8577 Sendai, Japan.|Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 332-0012 Saitama, Japan.
authors.forename: Masanori
authors.identifier: 0000-0001-5222-9163
authors.initials: M
authors.lastname: Izumi
authors.affiliation: Department of Applied Plant Sciences, Graduate School of Agricultural Sciences, Tohoku University, 981-8555 Sendai, Japan.
authors.forename: Hiroyuki
authors.identifier: 0000-0002-8682-4566
authors.initials: H
authors.lastname: Ishida
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 980-8577 Sendai, Japan.
authors.forename: Sakuya
authors.identifier: 0000-0002-8218-6894
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, 980-8577 Sendai, Japan.
authors.forename: Jun
authors.identifier: 0000-0002-3798-8257
authors.initials: J
authors.lastname: Hidema
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects / Q000648:ultrastructure; D001343:Autophagy; D001692:Biological Transport; D002468:Cell Physiological Phenomena; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects; D013312:Stress, Physiological; D014466:Ultraviolet Rays; D014617:Vacuoles / Q000378:metabolism*