Saji Shoko, Bathula Srinivas, Kubo Akihiro, Tamaoki Masanori, Aono Mitsuko, Sano Tomoharu, Tobe Kazuo, Timm Stefan, Bauwe Hermann, Nakajima Nobuyoshi, Saji Hikaru
Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, Japan.
Department of Biotechnology, School of Herbal Studies and Naturo Sciences, Dravidian University, Kuppam, Andhra Pradesh, India.
Plant Cell Physiol. 2017 May 1;58(5):914-924. doi: 10.1093/pcp/pcx027.
An ozone-sensitive mutant was isolated from T-DNA-tagged lines of Arabidopsis thaliana. The T-DNA was inserted at a locus on chromosome 3, where two genes encoding glycolate oxidases, GOX1 and GOX2, peroxisomal enzymes involved in photorespiration, reside contiguously. The amounts of the mutant's foliar transcripts for these genes were reduced, and glycolate oxidase activity was approximately 60% of that of the wild-type plants. No difference in growth and appearance was observed between the mutant and the wild-type plants under normal conditions with ambient air under a light intensity of 100 µmol photons m-2 s-1. However, signs of severe damage, such as chlorosis and ion leakage from the tissue, rapidly appeared in mutant leaves in response to ozone treatment at a concentration of 0.2 µl l-1 under a higher light intensity of 350 µmol photons m-2 s-1 that caused no such symptoms in the wild-type plant. The mutant also exhibited sensitivity to sulfur dioxide and long-term high-intensity light. Arabidopsis mutants with deficiencies in other photorespiratory enzymes such as glutamate:glyoxylate aminotransferase and hydroxypyruvate reductase also exhibited ozone sensitivities. Therefore, photorespiration appears to be involved in protection against photooxidative stress caused by ozone and other abiotic factors under high-intensity light.
从拟南芥的T-DNA标签系中分离出一个对臭氧敏感的突变体。T-DNA插入到3号染色体上的一个位点，在该位点上，两个编码乙醇酸氧化酶（GOX1和GOX2）的基因相邻存在，乙醇酸氧化酶是参与光呼吸的过氧化物酶体酶。该突变体中这些基因的叶片转录本数量减少，乙醇酸氧化酶活性约为野生型植株的60%。在100 μmol光子 m-2 s-1的光照强度下，正常环境空气中，突变体和野生型植株在生长和外观上没有差异。然而，在350 μmol光子 m-2 s-1的较高光照强度下，对突变体叶片进行0.2 μl l-1浓度的臭氧处理时，会迅速出现严重损伤的迹象，如组织黄化和离子泄漏，而野生型植株则不会出现这些症状。该突变体对二氧化硫和长期高强度光照也表现出敏感性。其他光呼吸酶（如谷氨酸：乙醛酸氨基转移酶和羟基丙酮酸还原酶）缺乏的拟南芥突变体也表现出对臭氧的敏感性。因此，在高强度光照下，光呼吸似乎参与了对由臭氧和其他非生物因素引起的光氧化胁迫的保护作用。
