Activity levels and expression of antioxidant enzymes in the ascorbate-glutathione cycle in artificially aged rice seed.
Reactive oxygen species are the main contributors to seed deterioration. In order to study scavenging systems for reactive oxygen species in aged seed, we performed analyses using western blotting, real-time quantitative reverse-transcription polymerase chain reaction, high-performance liquid chromatography, and antioxidant enzyme activity analyses in artificially aged rice seeds (Oryza sativa L. cv. wanhua no.11). Aging seeds by storing them at 50 °C for 1, 9, or 17 months increased the superoxide radical and hydrogen peroxide levels and reduced the germination percentage from 99% to 92%, 55%, and 2%, respectively. The activity levels of superoxide dismutase (SOD), glutathione reductase (GR), and dehydroascorbate reductase (DHAR) did not change in aged seeds. In contrast, the activity levels of catalase (CAT), ascorbate peroxidase (APX), and monodehydroascorbate reductase (MDHAR) were significantly decreased in aged seeds, as were the expression of catalase and cytosolic ascorbate peroxidase protein. Transcript accumulation analysis showed that specific expression patterns were complex for each of the antioxidant enzyme types in the rice embryos. Overall, the expression of most genes was down-regulated, along with their protein expression. In addition, the reduction in the amount of ascorbate and glutathione was associated with the reduction in scavenging enzymes activity in aged rice embryos. Our data suggest that the depression of the antioxidant system, especially the reduction in the expression of CAT1, APX1 and MDHAR1, may be responsible for the accumulation of reactive oxygen species in artificially aged seed embryos, leading to a loss of seed vigor.
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Guangkun
G
Yin
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Xia
X
Xin
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Chao
C
Song
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Xiaoling
X
Chen
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Jinmei
J
Zhang
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Shuhua
S
Wu
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Ruifang
R
Li
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Xu
X
Liu
National Genebank, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: luxinxiong@caas.cn.
Xinxiong
X
Lu
D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism; D012275:Oryza / Q000201:enzymology* / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D010940:Plant Proteins; D010088:Oxidoreductases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; C020666:glutathione dehydrogenase (ascorbate); D005978:Glutathione; D001205:Ascorbic Acid
Artificial aging; Ascorbate–glutathione cycle; Rice seed