Identification of a Novel Mutation Exacerbated the PSI Photoinhibition in <i>pgr5</i>/<i>pgrl1</i> Mutants; Caution for Overestimation of the Phenotypes in Arabidopsis <i>pgr5-1</i> Mutant
PSI photoinhibition is usually avoided through P700 oxidation. Without this protective mechanism, excess light represents a potentially lethal threat to plants. PGR5 is suggested to be a major component of cyclic electron transport around PSI and is important for P700 oxidation in angiosperms. The k...
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| Main Authors: | , , |
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| Format: | article |
| Language: | EN |
| Published: |
MDPI AG
2021
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| Subjects: | |
| Online Access: | https://doaj.org/article/71ec2f81f50742fc99214440ab9e88d2 |
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| Summary: | PSI photoinhibition is usually avoided through P700 oxidation. Without this protective mechanism, excess light represents a potentially lethal threat to plants. PGR5 is suggested to be a major component of cyclic electron transport around PSI and is important for P700 oxidation in angiosperms. The known Arabidopsis PGR5 deficient mutant, <i>pgr5-1</i>, is incapable of P700 oxidation regulation and has been used in numerous photosynthetic studies. However, here it was revealed that <i>pgr5-1</i> was a double mutant with exaggerated PSI photoinhibition. <i>pgr5-1</i> significantly reduced growth compared to the newly isolated PGR5 deficient mutant, <i>pgr5<sup>hope1</sup></i>. The introduction of PGR5 into <i>pgr5-1</i> restored P700 oxidation regulation, but remained a pale-green phenotype, indicating that <i>pgr5-1</i> had additional mutations. Both <i>pgr5-1</i> and <i>pgr5<sup>hope1</sup></i> tended to cause PSI photoinhibition by excess light, but <i>pgr5-1</i> exhibited an enhanced reduction in PSI activity. Introducing AT2G17240, a candidate gene for the second mutation into <i>pgr5-1</i> restored the pale-green phenotype and partially restored PSI activity. Furthermore, a deficient mutant of PGRL1 complexing with PGR5 significantly reduced PSI activity in the double-deficient mutant with AT2G17240. From these results, we concluded that AT2G17240, named PSI photoprotection 1 (PTP1), played a role in PSI photoprotection, especially in PGR5/PGRL1 deficient mutants. |
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