Autophagy-deficient Arabidopsis mutant atg5, which shows ultraviolet-B sensitivity, cannot remove ultraviolet-B-induced fragmented mitochondria

Abstract

UV-B led to the inactivation and fragmentation of mitochondria, which are removed by mitophagy. Mitophagy might be one of the important repair mechanisms for UV-B-induced damage in Arabidopsis.

222 nm ultraviolet radiation C causes more severe damage to guard cells and epidermal cells of Arabidopsis plants than does 254 nm ultraviolet radiation

“…A transgenic Arabidopsis line in the Columbia background harboring mitochondrial matrix-targeted yellow fluorescent protein (MT-YFP) driven by Pro35S was used [ 15 ]. The transgenic Arabidopsis line MT-YFP-WT was grown vertically on ½-strength Murashige and Skoog (MS) medium agar plates in chambers at 23 °C under a 16 h light/8 h dark photoperiod provided by white fluorescent lamps (140 μmol m −2 s −1 ).…”

“…LSCM imaging was performed using a C-Apochromat LD63 × water-immersion objective (numerical aperture = 1.15; LSM800, Carl Zeiss, Oberkochen, Germany). Fluorescence images of YFP (excitation at 488 nm; emission at 500–550 nm) and chlorophyll autofluorescence (excitation at 640 nm; emission at 650–700 nm) were subsequently obtained [ 15 ].…”

“…Fixed image areas (212 × 212 × 40 μm each) were monitored by changing the focus during LSCM. The Z-stack images from LSCM were converted to three-dimensional pictures, and the number and volume of mitochondria were measured using Imaris microscopy analysis software (Bitplane, Zurich, Switzerland) [ 15 ]. To determine the number and volume of mitochondria, three plants at each timepoint were analyzed [ n = 3 (≥ 5 cells)].…”

“…To understand the effects of high doses of 222-UVC irradiation on plants, we investigated the growth inhibition and cell damage caused by 222-UVC exposure. We previously demonstrated that a high dose of UVB radiation disrupts mitochondrial function and causes mitochondrial fragmentation in the mesophyll cells of Arabidopsis leaves, and that the accumulation of mitochondria damaged by UVB radiation in the cells contributes to UVB-induced growth inhibition [ 15 ]. In this study, to understand the effects of 222-UVC irradiation on Arabidopsis plant, 222-UVC-induced growth inhibition and the mitochondrial dynamics in the epidermis and mesophyll cells of Arabidopsis were investigated, compared with that of 254-UVC-irradiated Arabidopsis .…”

How Lipids Contribute to Autophagosome Biogenesis, a Critical Process in Plant Responses to Stresses

“…The induction of autophagy in response to environmental or developmental cues is finely regulated by multiple mechanisms. Notably, several studies have shown that the expression of ATG genes is modified during plant development with an upregulation during senescence [ 92 ], and upon exposure to various autophagy-inducing stresses (including nitrogen and carbon deficiency [ 93 , 94 , 95 , 96 ], osmotic stresses [ 52 , 94 , 95 , 97 , 98 ], heat and cold stresses [ 53 , 94 , 95 , 98 , 99 ], light quality and intensity [ 97 , 100 ], hypoxia [ 85 ], biotic stress [ 93 ], and viruses infection [ 77 , 78 , 84 , 98 , 99 , 101 ]). Transcriptional regulation of autophagy involves WRKY, one of the largest family of TFs in plants [ 102 ], as silencing of WRKY33a and WRKY33b in tomato during heat stress was found to cause a decrease in ATG genes expression and a reduction in AP formation [ 103 ].…”