TY - JOUR
T1 - Characterization of photosynthetic pigment composition, photosystem II photochemistry and thermal energy dissipation during leaf senescence of wheat plants grown in the field
AU - Lu, Congming
AU - Lu, Qingtao
AU - Zhang, Jianhua
AU - Kuang, Tingyun
N1 - Funding Information:
This work was supported by the Program of 100 Distinguished Young Scientists of the Chinese Academy of Sciences, the State Key Basic Research and Development Plan of China (No. G1998010100), the Innovative Foundation of the Laboratory of Photosynthesis Research, Institute of Botany, Chinese Academy of Sciences (CL), as well as the Hong Kong Baptist University (FRG grant) (CL, JZ).
PY - 2001
Y1 - 2001
N2 - Photosynthetic pigment composition and photosystem II (PSII) photochemistry were characterized during the flag leaf senescence of wheat plants grown in the field. During leaf senescence, neoxanthin and β-carotene decreased concomitantly with chlorophyll, whereas lutein and xanthophyll cycle pigments were less affected, leading to increases in lutein/chlorophyll and xanthophyll cycle pigments/chlorophyll ratios. The chlorophyll a/b ratio also increased. With the progression of senescence, the maximal efficiency of PSII photochemistry decreased only slightly in the early morning (low light conditions), but substantially at midday (high light conditions). Actual PSII efficiency, photochemical quenching and the efficiency of excitation capture by open PSII centres decreased significantly both early in the morning and at midday and such decreases were much greater at midday than in the early morning. At the same time, non-photochemical quenching, zeaxanthin and antheraxanthin contents at the expense of violaxanthin increased both early in the morning and at midday, with a greater increase at midday. The results in the present study suggest that a down-regulation of PSII occurred in senescent leaves and that the xanthophyll cycle plays a role in the protection of PSII from photoinhibitory damage in senescent leaves by dissipating excess excitation energy, particularly when exposed to high light.
AB - Photosynthetic pigment composition and photosystem II (PSII) photochemistry were characterized during the flag leaf senescence of wheat plants grown in the field. During leaf senescence, neoxanthin and β-carotene decreased concomitantly with chlorophyll, whereas lutein and xanthophyll cycle pigments were less affected, leading to increases in lutein/chlorophyll and xanthophyll cycle pigments/chlorophyll ratios. The chlorophyll a/b ratio also increased. With the progression of senescence, the maximal efficiency of PSII photochemistry decreased only slightly in the early morning (low light conditions), but substantially at midday (high light conditions). Actual PSII efficiency, photochemical quenching and the efficiency of excitation capture by open PSII centres decreased significantly both early in the morning and at midday and such decreases were much greater at midday than in the early morning. At the same time, non-photochemical quenching, zeaxanthin and antheraxanthin contents at the expense of violaxanthin increased both early in the morning and at midday, with a greater increase at midday. The results in the present study suggest that a down-regulation of PSII occurred in senescent leaves and that the xanthophyll cycle plays a role in the protection of PSII from photoinhibitory damage in senescent leaves by dissipating excess excitation energy, particularly when exposed to high light.
KW - Chlorophyll fluorescence
KW - Photosystem II photochemistry
KW - Pigment composition
KW - Wheat (Triticum aestivum L.)
KW - Xanthophyll cycle
UR - http://www.scopus.com/inward/record.url?scp=0034845212&partnerID=8YFLogxK
U2 - 10.1093/jexbot/52.362.1805
DO - 10.1093/jexbot/52.362.1805
M3 - Journal article
C2 - 11520868
AN - SCOPUS:0034845212
SN - 0022-0957
VL - 52
SP - 1805
EP - 1810
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
IS - 362
ER -