Thylakoid dismantling of damaged unfunctional chloroplasts modulates the Cab and RbcS gene expression in wheat leaves

Nicoletta La Rocca, Roberto Barbato, Angelo Bonora, Luisa Dalla Valle, Stefania De Faveri, Nicoletta Rascio

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

Thylakoid membrane dismantling and Lhcb and RbcS nuclear gene expression have been analysed in leaves of wheat plants grown in high fluence rate light and deprived of photoprotective carotenoids by treatments with the two bleaching herbicides, either norflurazon or amitrole. The Lhcb transcript was not detectable in cells of norflurazon-supplied leaves, having chloroplasts totally devoid of both inner membranes and pigments. In contrast, a substantial amount of Lhcb mRNA could be found in cells of amitrole-treated leaves, whose severely damaged organelles still contained few strikingly altered and photosynthetically unfunctional thylakoids, as well as chlorophyll traces. A possible relationship between chlorophyll synthesis and Lhcb expression, with the transcript level depending on the rate of pigment production in photodamaged chloroplasts is discussed. Also the RbcS expression was linked to the chloroplast membrane photodamage. However, a detectable level of transcript was still produced in norflurazon-treated cells, despite complete thylakoid demolition. Thus, the wheat cell behaviour had to be placed between that of species, such as maize, in which the RbcS expression is broken off in these conditions, and that of species, such as pea, in which it is slightly lowered. Interestingly, the dramatically photodamaged chloroplasts still maintained the ability to synthesize proteins and this allowed SSU and LSU Rubisco subunits to be found in the organelles of both norflurazon- and amitrole-treated plants.

Lingua originaleInglese
pagine (da-a)159-166
Numero di pagine8
RivistaJournal of Photochemistry and Photobiology B: Biology
Volume73
Numero di pubblicazione3
DOI
Stato di pubblicazionePubblicato - 20 feb 2004

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