TY - JOUR
T1 - Thylakoid dismantling of damaged unfunctional chloroplasts modulates the Cab and RbcS gene expression in wheat leaves
AU - La Rocca, Nicoletta
AU - Barbato, Roberto
AU - Bonora, Angelo
AU - Dalla Valle, Luisa
AU - De Faveri, Stefania
AU - Rascio, Nicoletta
N1 - Funding Information:
This research was supported by grants from M.U.R.S.T.
PY - 2004/2/20
Y1 - 2004/2/20
N2 - 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.
AB - 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.
KW - Bleaching herbicides
KW - Chloroplast photooxidation
KW - Lhcb gene expression
KW - Plastid factor
KW - RbcS gene expression
KW - Triticum aestivum L.
UR - http://www.scopus.com/inward/record.url?scp=1142311528&partnerID=8YFLogxK
U2 - 10.1016/j.jphotobiol.2003.12.001
DO - 10.1016/j.jphotobiol.2003.12.001
M3 - Article
SN - 1011-1344
VL - 73
SP - 159
EP - 166
JO - Journal of Photochemistry and Photobiology B: Biology
JF - Journal of Photochemistry and Photobiology B: Biology
IS - 3
ER -