摘要:

Abstract—Synthesis* of the enzyme lipoxygenase (LOG)† in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by phytochrome (Pfr) through a threshold (all‐or‐none) mechanism. The data of the present paper confirm the previous assumption (Oelze‐Karow and Mohr, 1973) that the primary reaction of Pfr(Pfr+ X → PfrX ⇄ PfrX‘) is the site of the highly cooperative threshold reaction. Suppression of LOG synthesis depends on the presence of PfrX’. However, PfrX‘ is only stable above the threshold level of Pfr. If the level of Pfris below the threshold, PfrX is stable, and no suppression of LOG synthesis occurs. As long as the level of Pfrremains below the threshold, no destruction of Pfrtakes place. Destruction of Pfroccurs only as long as [Pfr]†is above the threshold level. Thus the simplest formulation of the actual threshold reaction in the LOG response is PfrX⇄frX’ state at [Pfr] below threshold no Pfrdestruction LOG synthesis suppressed state at [Pfr] above threshold Pfrdestruction(1kdLOG synthesis unimpaired The reversible threshold reaction is thus an integral part of the “primary reaction” of Pfroccurring at the “matrix” specific for the LOG response. The data and conclusions on the LOG response are consistent with an “open phytochrome‐receptor model” recently advanced by E. Schäfer (1975). The data are not consistent with the concept that a rapid dark reversion (Pfr→Pr) exists in dicotyledonous seedlings and that the degree of Pfrdark reversion strongly depends on the initial photostationary state,

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1976.tb06772.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1976.tb06773.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1976.tb06774.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1976.tb06775.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1976.tb06776.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY