New Phytologist
Abstract
In self-incompatible Petunia species, the pistil S-RNase acts as cytotoxin to inhibit self-pollination but is polyubiquitinated by the pollen-specific nonself S-locus F-box (SLF) proteins and subsequently degraded by the ubiquitin-proteasome system (UPS), allowing cross-pollination. However, it remains unclear how S-RNase is restricted by the UPS.
Using biochemical analyses, we first show that Petunia hybrida S3-RNase is largely ubiquitinated by K48-linked polyubiquitin chains at three regions, R I, R II and R III. R I is ubiquitinated in unpollinated, self-pollinated and cross-pollinated pistils, indicating its occurrence before PhS3-RNase uptake into pollen tubes, whereas R II and R III are exclusively ubiquitinated in cross-pollinated pistils.
Transgenic analyses showed that removal of R II ubiquitination resulted in significantly reduced seed sets from cross-pollination and that of R I and R III to a lesser extent, indicating their increased cytotoxicity. Consistent with this, the mutated R II of PhS3-RNase resulted in a marked reduction of its degradation, whereas that of R I and R III resulted in less reduction.
Taken together, we demonstrate that PhS3-RNase R II functions as a major ubiquitination region for its destruction and R I and R III as minor ones, revealing that its cytotoxicity is primarily restricted by a stepwise UPS mechanism for cross-pollination in P. hybrida.
| 论文编号: | DOI:10.1111/nph.17438 |
| 论文题目: | Primary Restriction of S-RNase Cytotoxicity by A Stepwise Ubiquitination and Degradation Pathway in Petunia Hybrida |
| 英文论文题目: | Primary Restriction of S-RNase Cytotoxicity by A Stepwise Ubiquitination and Degradation Pathway in Petunia Hybrida |
| 第一作者: | Hong Zhao, Yanzhai Song, Junhui Li, Yue Zhang, Huaqiu Huang, Qun Li, Yu’e Zhang and Yongbiao Xue |
| 英文第一作者: | Hong Zhao, Yanzhai Song, Junhui Li, Yue Zhang, Huaqiu Huang, Qun Li, Yu’e Zhang and Yongbiao Xue |
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| 发表年度: | 2021-06-01 |
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| 摘要: | In self-incompatible Petunia species, the pistil S-RNase acts as cytotoxin to inhibit self-pollination but is polyubiquitinated by the pollen-specific nonself S-locus F-box (SLF) proteins and subsequently degraded by the ubiquitin-proteasome system (UPS), allowing cross-pollination. However, it remains unclear how S-RNase is restricted by the UPS. Using biochemical analyses, we first show that Petunia hybrida S3-RNase is largely ubiquitinated by K48-linked polyubiquitin chains at three regions, R I, R II and R III. R I is ubiquitinated in unpollinated, self-pollinated and cross-pollinated pistils, indicating its occurrence before PhS3-RNase uptake into pollen tubes, whereas R II and R III are exclusively ubiquitinated in cross-pollinated pistils. Transgenic analyses showed that removal of R II ubiquitination resulted in significantly reduced seed sets from cross-pollination and that of R I and R III to a lesser extent, indicating their increased cytotoxicity. Consistent with this, the mutated R II of PhS3-RNase resulted in a marked reduction of its degradation, whereas that of R I and R III resulted in less reduction. Taken together, we demonstrate that PhS3-RNase R II functions as a major ubiquitination region for its destruction and R I and R III as minor ones, revealing that its cytotoxicity is primarily restricted by a stepwise UPS mechanism for cross-pollination in P. hybrida. |
| 英文摘要: | In self-incompatible Petunia species, the pistil S-RNase acts as cytotoxin to inhibit self-pollination but is polyubiquitinated by the pollen-specific nonself S-locus F-box (SLF) proteins and subsequently degraded by the ubiquitin-proteasome system (UPS), allowing cross-pollination. However, it remains unclear how S-RNase is restricted by the UPS. Using biochemical analyses, we first show that Petunia hybrida S3-RNase is largely ubiquitinated by K48-linked polyubiquitin chains at three regions, R I, R II and R III. R I is ubiquitinated in unpollinated, self-pollinated and cross-pollinated pistils, indicating its occurrence before PhS3-RNase uptake into pollen tubes, whereas R II and R III are exclusively ubiquitinated in cross-pollinated pistils. Transgenic analyses showed that removal of R II ubiquitination resulted in significantly reduced seed sets from cross-pollination and that of R I and R III to a lesser extent, indicating their increased cytotoxicity. Consistent with this, the mutated R II of PhS3-RNase resulted in a marked reduction of its degradation, whereas that of R I and R III resulted in less reduction. Taken together, we demonstrate that PhS3-RNase R II functions as a major ubiquitination region for its destruction and R I and R III as minor ones, revealing that its cytotoxicity is primarily restricted by a stepwise UPS mechanism for cross-pollination in P. hybrida. |
| 刊物名称: | New Phytologist |
| 英文刊物名称: | New Phytologist |
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| 其它备注: | Hong Zhao, Yanzhai Song, Junhui Li, Yue Zhang, Huaqiu Huang, Qun Li, Yu’e Zhang and Yongbiao Xue. Primary Restriction of S-RNase Cytotoxicity by A Stepwise Ubiquitination and Degradation Pathway in Petunia Hybrida. New Phytologist. DOI:10.1111/nph.17438. |
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