The site of photoinhibition in leaves of Cucumis sativus L. at low temperatures is photosystem I, not photosystem II

Ichiro Terashima, Sachiko Funayama, Kintake Sonoike*

*この研究の対応する著者

研究成果: Article査読

233 被引用数 (Scopus)

抄録

Maximum quantum yields (QY) of photosynthetic electron flows through PSI and PSII were separately assessed in thylakoid membranes isolated from leaves of Cucumis sativus L. (cucumber) that had been chilled in various ways. The QY(PSI) in the thylakoids prepared from the leaves treated at 4° C in moderate light at 220 μmol quanta·m-2·s-1 (400-700 nm) for 5 h, was about 20-30% of that in the thylakoids prepared from untreated leaves, while QY(PSII) decreased, at most, by 20% in response to the same treatment. The decrease in QY(PSI) was observed only when the leaves were chilled at temperatures below 10° C, while such a marked temperature dependency was not observed for the decrease in QY(PSII). In the chilling treatment at 4° C for 5 h, the quantum flux density that was required to induce 50% loss of QY (PSI) was ca. 50 umol quanta·m-2·s-1. When the chilling treatment at 4° C in the light was conducted in an atmosphere of N2, photoinhibition of PSI was largely suppressed, while the damage to PSII was somewhat enhanced. The ferricyanide-oxidised minus ascorbate-reduced difference spectra and the light-induced absorbance changes at 700 nm obtained with the thylakoid suspension, indicated the loss of P700 to extents that corresponded to the decreases in QY(PSI). Accordingly, the decreases in QY(PSI) can largely be attributed to destruction of the PSI reaction centre itself. These results clearly show that, at least in cucumber, a typical chillingsensitive plant, PSI is much more susceptible to aerobic photoinhibition than PSII.

本文言語English
ページ(範囲)300-306
ページ数7
ジャーナルPlanta
193
2
DOI
出版ステータスPublished - 1994 3月 1
外部発表はい

ASJC Scopus subject areas

  • 遺伝学
  • 植物科学

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