
TY  - JOUR
A1  - Lu, Congming 
A1  - Lu, Qingtao 
A1  - Zhang, Jianhua 
A1  - Zhang, Qide 
A1  - Kuang, Tingyun 
T1  - Xanthophyll cycle, light energy dissipation and photosystem II down-regulation in senescent leaves of wheat plants grown in the field
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2001
VL  - 28
IS  - 10
SP  - 1023
EP  - 1030
KW  - chlorophyll fluorescence; leaf senescence; photosystem II; photosynthesis; thermal energy dissipation; xanthophyll cycle.
UR  - https://doi.org/10.1071/PP01109 
N2  - Photosynthesis, the xanthophyll cycle, light energy dissipation and down-regulation of photosystem II (PSII) in senescent leaves of wheat plants grown in the field were investigated. With the progress of senescence, maximal efficiency of PSII photochemistry decreased only slightly early in the morning but substantially at midday. Actual PSII efficiency, photochemical quenching, efficiency of excitation capture by open PSII centres, and the I&#8211;P phase of fluorescence induction curves decreased significantly and such decreases were much more evident at midday than in the morning. At the same time, non-photochemical quenching, thermal dissipation and de-epoxidation status of the xanthophyll cycle increased, with much greater increases at midday than in the morning. These results suggest that the xanthophyll cycle played a role in photoprotection of PSII in senescent leaves by dissipating excess excitation energy. Taking into account the substantial decrease in photosynthetic capacity in senescent leaves, our data seem to support the view that the decrease in actual PSII efficiency in senescent leaves may represent a mechanism to down-regulate photosynthetic electron transport to match the decreased CO2 assimilation capacity and avoid photodamage of PSII from excess excitation energy. 
ER  -

