Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination
Seed germination is a complicated biological process that requires regulation through various enzymatic and non-enzymatic mechanisms. Although it has been recognized that reactive oxygen species (ROS) regulate radicle emergence and root elongation in a non-enzymatic manner during dicot seed germinat...
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MDPI AG
2017-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | http://www.mdpi.com/1422-0067/18/1/110 |
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| author | Wen-Yan Li Bing-Xian Chen Zhong-Jian Chen Yin-Tao Gao Zhuang Chen Jun Liu |
| author_facet | Wen-Yan Li Bing-Xian Chen Zhong-Jian Chen Yin-Tao Gao Zhuang Chen Jun Liu |
| author_sort | Wen-Yan Li |
| collection | DOAJ |
| description | Seed germination is a complicated biological process that requires regulation through various enzymatic and non-enzymatic mechanisms. Although it has been recognized that reactive oxygen species (ROS) regulate radicle emergence and root elongation in a non-enzymatic manner during dicot seed germination, the role of ROS in monocot seed germination remains unknown. NADPH oxidases (NOXs) are the major ROS producers in plants; however, whether and how NOXs regulate rice seed germination through ROS generation remains unclear. Here, we report that diphenyleneiodinium (DPI), a specific NOX inhibitor, potently inhibited embryo and seedling growth—especially that of the radicle and of root elongation—in a dose-dependent manner. Notably, the DPI-mediated inhibition of radicle and root growth could be eliminated by transferring seedlings from DPI to water. Furthermore, ROS production/accumulation during rice seed germination was quantified via histochemistry. Superoxide radicals (O2−), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) accumulated steadily in the coleorhiza, radicle and seedling root of germinating rice seeds. Expression profiles of the nine typical NOX genes were also investigated. According to quantitative PCR, OsNOX5, 7 and 9 were expressed relatively higher. When seeds were incubated in water, OsNOX5 expression progressively increased in the embryo from 12 to 48 h, whereas OsNOX7 and 9 expressions increased from 12 to 24 h and decreased thereafter. As expected, DPI inhibits the expression at predetermined time points for each of these genes. Taken together, these results suggest that ROS produced by NOXs are involved in radicle and root elongation during rice seed germination, and OsNOX5, 7 and 9 could play crucial roles in rice seed germination. These findings will facilitate further studies of the roles of ROS generated by NOXs during seed germination and seedling establishment and also provide valuable information for the regulation of NOX family gene expression in germinating seeds of monocot cereals. |
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| spelling | doaj.art-710f00eb973f493ab6def3adf5f66c7b2022-12-22T02:50:11ZengMDPI AGInternational Journal of Molecular Sciences1422-00672017-01-0118111010.3390/ijms18010110ijms18010110Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed GerminationWen-Yan Li0Bing-Xian Chen1Zhong-Jian Chen2Yin-Tao Gao3Zhuang Chen4Jun Liu5Argo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaArgo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaArgo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaArgo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaArgo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaArgo-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, ChinaSeed germination is a complicated biological process that requires regulation through various enzymatic and non-enzymatic mechanisms. Although it has been recognized that reactive oxygen species (ROS) regulate radicle emergence and root elongation in a non-enzymatic manner during dicot seed germination, the role of ROS in monocot seed germination remains unknown. NADPH oxidases (NOXs) are the major ROS producers in plants; however, whether and how NOXs regulate rice seed germination through ROS generation remains unclear. Here, we report that diphenyleneiodinium (DPI), a specific NOX inhibitor, potently inhibited embryo and seedling growth—especially that of the radicle and of root elongation—in a dose-dependent manner. Notably, the DPI-mediated inhibition of radicle and root growth could be eliminated by transferring seedlings from DPI to water. Furthermore, ROS production/accumulation during rice seed germination was quantified via histochemistry. Superoxide radicals (O2−), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) accumulated steadily in the coleorhiza, radicle and seedling root of germinating rice seeds. Expression profiles of the nine typical NOX genes were also investigated. According to quantitative PCR, OsNOX5, 7 and 9 were expressed relatively higher. When seeds were incubated in water, OsNOX5 expression progressively increased in the embryo from 12 to 48 h, whereas OsNOX7 and 9 expressions increased from 12 to 24 h and decreased thereafter. As expected, DPI inhibits the expression at predetermined time points for each of these genes. Taken together, these results suggest that ROS produced by NOXs are involved in radicle and root elongation during rice seed germination, and OsNOX5, 7 and 9 could play crucial roles in rice seed germination. These findings will facilitate further studies of the roles of ROS generated by NOXs during seed germination and seedling establishment and also provide valuable information for the regulation of NOX family gene expression in germinating seeds of monocot cereals.http://www.mdpi.com/1422-0067/18/1/110seed germinationNADPH oxidasesreactive oxygen species (ROS)Oryza sativaradicle and root elongationgene expression |
| spellingShingle | Wen-Yan Li Bing-Xian Chen Zhong-Jian Chen Yin-Tao Gao Zhuang Chen Jun Liu Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination International Journal of Molecular Sciences seed germination NADPH oxidases reactive oxygen species (ROS) Oryza sativa radicle and root elongation gene expression |
| title | Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination |
| title_full | Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination |
| title_fullStr | Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination |
| title_full_unstemmed | Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination |
| title_short | Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination |
| title_sort | reactive oxygen species generated by nadph oxidases promote radicle protrusion and root elongation during rice seed germination |
| topic | seed germination NADPH oxidases reactive oxygen species (ROS) Oryza sativa radicle and root elongation gene expression |
| url | http://www.mdpi.com/1422-0067/18/1/110 |
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