Autophagy Contributes to Leaf Starch Degradation

Wang, Yan; Yu, Bingjie; Zhao, Jinping; Guo, Jian-Wei; Liu, Ying; Han, Shaojie; Huang, Lei; Du, Yumei; Hong, Yiguo; Tang, Dingzhong; Liu, Yule

doi:10.1105/tpc.112.108993

Cited by 225 publications

(223 citation statements)

References 100 publications

(133 reference statements)

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“…However, whether the increase in autophagosome frequency reflects a direct role for ESCRT in the formation/maturation of autophagosomes or autophagy induction remained controversial. The chmp1 mutant shares many phenotypic defects with atg mutants, including reduced degradation of some plastid proteins, aberrant plastid division, and a hyperaccumulation of starch Wang et al, 2013). These phenomena, together with the presence of arrested phagophores and the reduced autophagy-mediated degradation of the plastid marker RECA-GFP, clearly point to a direct role for CHMP1 in plastid autophagy.…”

Section: A Mechanistic Connection Between Escrt Proteins and Autophagymentioning

confidence: 96%

The Endosomal Protein CHARGED MULTIVESICULAR BODY PROTEIN1 Regulates the Autophagic Turnover of Plastids in Arabidopsis

et al. 2015

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Endosomal Sorting Complex Required for Transport (ESCRT)-III proteins mediate membrane remodeling and the release of endosomal intraluminal vesicles into multivesicular bodies. Here, we show that the ESCRT-III subunit paralogs CHARGED MULTIVESICULAR BODY PROTEIN1 (CHMP1A) and CHMP1B are required for autophagic degradation of plastid proteins in Arabidopsis thaliana. Similar to autophagy mutants, chmp1a chmp1b (chmp1) plants hyperaccumulated plastid components, including proteins involved in plastid division. The autophagy machinery directed the release of bodies containing plastid material into the cytoplasm, whereas CHMP1A and B were required for delivery of these bodies to the vacuole. Autophagy was upregulated in chmp1 as indicated by an increase in vacuolar green fluorescent protein (GFP) cleavage from the autophagic reporter GFP-ATG8. However, autophagic degradation of the stromal cargo RECA-GFP was drastically reduced in the chmp1 plants upon starvation, suggesting that CHMP1 mediates the efficient delivery of autophagic plastid cargo to the vacuole. Consistent with the compromised degradation of plastid proteins, chmp1 plastids show severe morphological defects and aberrant division. We propose that CHMP1 plays a direct role in the autophagic turnover of plastid constituents.

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Section: A Mechanistic Connection Between Escrt Proteins and Autophagymentioning

confidence: 96%

The Endosomal Protein CHARGED MULTIVESICULAR BODY PROTEIN1 Regulates the Autophagic Turnover of Plastids in Arabidopsis

et al. 2015

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“…Nicotiana benthamiana plants were grown and transformed by infiltration of leaves with Agrobacterium tumefaciens by the protocol of Wang et al (2013). Hypoxia treatment of N. benthamiana leaf sections was performed essentially as described previously (Weber et al, 2008;Sorenson and Bailey-Serres, 2014).…”

Section: Plant Growth Conditions and Stress Treatment Protocolsmentioning

confidence: 99%

Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress

et al. 2015

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During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38: YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses.

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“…These two proteins defined a newly identified stressinduced compartment that moves along the ER network and is subsequently transported to the vacuole . Because autophagy-dependent degradation of plastid components was previously suggested (Ishida et al, 2008;Wang et al, 2013), we were interested in examining whether ATG8-INTERACTING PROTEIN1 (ATI1) might be involved in such a process. In this article, we show that in response to carbon (C) starvation stress that leads to senescence, ATI1 is associated with bodies located on the surface of plastids as well as inside their stroma.…”

Section: Introductionmentioning

confidence: 99%

ArabidopsisATG8-INTERACTING PROTEIN1 Is Involved in Autophagy-Dependent Vesicular Trafficking of Plastid Proteins to the Vacuole

et al. 2014

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Selective autophagy has been extensively studied in various organisms, but knowledge regarding its functions in plants, particularly in organelle turnover, is limited. We have recently discovered ATG8-INTERACTING PROTEIN1 (ATI1) from Arabidopsis thaliana and showed that following carbon starvation it is localized on endoplasmic reticulum (ER)-associated bodies that are subsequently transported to the vacuole. Here, we show that following carbon starvation ATI1 is also located on bodies associating with plastids, which are distinct from the ER ATI bodies and are detected mainly in senescing cells that exhibit plastid degradation. Additionally, these plastid-localized bodies contain a stroma protein marker as cargo and were observed budding and detaching from plastids. ATI1 interacts with plastid-localized proteins and was further shown to be required for the turnover of one of them, as a representative. ATI1 on the plastid bodies also interacts with ATG8f, which apparently leads to the targeting of the plastid bodies to the vacuole by a process that requires functional autophagy. Finally, we show that ATI1 is involved in Arabidopsis salt stress tolerance. Taken together, our results implicate ATI1 in autophagic plastid-to-vacuole trafficking through its ability to interact with both plastid proteins and ATG8 of the core autophagy machinery.

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Autophagy Contributes to Leaf Starch Degradation

Cited by 225 publications

References 100 publications

The Endosomal Protein CHARGED MULTIVESICULAR BODY PROTEIN1 Regulates the Autophagic Turnover of Plastids in Arabidopsis

The Endosomal Protein CHARGED MULTIVESICULAR BODY PROTEIN1 Regulates the Autophagic Turnover of Plastids in Arabidopsis

Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress

ArabidopsisATG8-INTERACTING PROTEIN1 Is Involved in Autophagy-Dependent Vesicular Trafficking of Plastid Proteins to the Vacuole

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