Study of Arabidopsis lines with identical mutation in PGR5 gene but with different growth phenotypes

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05769
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38010:Plant nutrition and soil science-related
• Research Institution: Kobe University
• Principal Investigator: Wada Shinya 神戸大学, 農学研究科, 助教 (80637942)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 光合成 / 電子伝達 / シロイヌナズナ / 循環的電子伝達 / 光ストレス

Outline of Final Research Achievements

The Arabidopsis mutant, pgr5-1, has been used in many studies, mainly for the analysis of cyclic electron transport in photosynthesis. We newly identified pgr5 mutant line, pgr5hope1, by our original selection. Although pgr5hope1 had the same point mutations as pgr5-1, it exhibited a different growth phenotype and photosynthetic ability than pgr5-1. In this study, we revealed the genetic factors responsible for the differences between these two pgr5-deficient mutants and analyzed how the differences in photosynthetic ability occur.
We revealed that the phenotypic difference between these mutants was caused by a mutation (designated ptp1) present in the pgr5-1. The ptp1 mutation had no effect on photosynthetic ability in the wild-type background, but increased PSI susceptibility to oxidative damage in the absence of pgr5. As a result, it was indicated that the decreased CO2 fixation rate observed in pgr5-1 was due to the oxidative damage of PSI enhanced by the ptp1 mutation.

Free Research Field

植物栄養学

Academic Significance and Societal Importance of the Research Achievements

これまで、主に光合成循環的電子伝達の解析材料としてシロイヌナズナPGR5欠損体pgr5-1株は世界中で利用されてきた。しかし観察されてきた一部のデータ、特に光合成CO2固定速度の変化はptp1変異による影響が強く、単純なPGR5欠損の影響ではないことが明らかとなった。この結果は、PGR5を基盤とした既存の循環的電子伝達の分子モデルやその役割に関し、議論の余地があることを示したものとなった。また、ptp1変異は植物にとって致命的となる光化学系Iの酸化障害を助長するものであることが明らかとなり、PSIの保護や回復など未だ知られていない分子機構の解明につながる知見となることが期待される。