Apple autophagy-related protein MdATG3s afford tolerance to multiple abiotic stresses.
The efficient degradation system of autophagy in plant cells has important roles in removing and recycling intracellular components during normal development or under environmental stresses. Formation of autophagosomes requires the conjugation of ubiquitin-like protein ATG8 to phosphatidylethanolamine (PE). We isolated two ubiquitin-conjugating enzyme E2-like ATG3 homologues from Malus domestica - MdATG3a and MdATG3b - that are crucial for ATG8-PE conjugation. Both share a conserved N-terminal, as well as the catalytic and C-terminal domains of ATG3 with HPC and FLKF motifs. Each promoter was isolated from genomic DNA and contained several cis-acting elements that are involved in responses to environmental stresses or hormones. In addition to having the same cellular localization in the nucleus and cytoplasm, MdATG3a and MdATG3b showed similar expression patterns toward leaf senescence, nitrogen starvation, drought, salinity, and oxidative stress at the transcriptional level. Ectopic expression of either in Arabidopsis conferred tolerance to osmotic or salinity stress and also improved growth performance under nitrogen- or carbon-starvation. Callus lines of 'Orin' apple that over-expressed MdATG3b also displayed better growth performance when nutrient supplies were limited. These overall results demonstrate that, as important autophagy genes, overexpression of MdATG3s can afford tolerance to multiple abiotic stresses at the cellular and whole-plant level.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
Ping
P
Wang
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
Xun
X
Sun
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
Xin
X
Jia
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China. Electronic address: fwm64@sina.com.
Fengwang
F
Ma
D000222:Adaptation, Physiological / Q000235:genetics*; D017360:Arabidopsis; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family / Q000235:genetics / Q000378:metabolism; D000071183:Autophagy-Related Proteins / Q000235:genetics* / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D017343:Genes, Plant; D027845:Malus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D013312:Stress, Physiological / Q000235:genetics*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics* / Q000378:metabolism
D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D010940:Plant Proteins; D002244:Carbon; D044763:Ubiquitin-Conjugating Enzymes; D009584:Nitrogen
ATG3; Abiotic stress; Apple; Arabidopsis; Autophagy; Overexpression