Heterogeneous behavior of PSII in soybean (Glycine max) leaves with identical PSII photochemistry efficiency under different high temperature treatments.
The purpose of this study is to demonstrate the heterogeneous behavior of PSII in soybean (Glycine max) leaves and identical maximum PSII photochemistry efficiency (F(V)/F(M)) under different high temperature treatments. We observed that, with an identical decrease in F(V)/F(M) in soybean leaves caused by different high temperature treatments, chlorophyll a fluorescence differed significantly, indicating different behaviors in the photosynthetic apparatus. The quantitative analysis showed that, with an identical F(V)/F(M), leaves treated at 48 degrees C showed a higher W(K), an indicator of damage to the oxygen-evolving complex along with a lower O(2) evolution rate compared with leaves treated at 45 degrees C. This demonstrated that the donor side of PSII was damaged more severely at 48 degrees C than at 45 degrees C despite the same decrease in F(V)/F(M) in the two heat-treated leaves. The ratios of Q(A)- and Q(B)-reducing PSII reaction centers to total PSII reaction centers were both lower in leaves treated at 48 degrees C than in leaves treated at 45 degrees C with an identical F(V)/F(M), indicating that the acceptor side of PSII was also more damaged by heat treatment at 48 degrees C than at 45 degrees C. However, when damage to the donor side of PSII was similar in leaves treated at two different temperatures, the acceptor side of PSII was damaged less severely at 48 degrees C, which accounted for higher electron transport rate at the acceptor side of PSII in leaves treated at 48 degrees C than in leaves treated at 45 degrees C.
Li
Pengmin
P
State Key Lab of Crop Biology; College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China.
Cheng
Lailiang
L
Gao
Huiyuan
H
Jiang
Chuangdao
C
Peng
Tao
T
D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005453:Fluorescence; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism*; D013025:Glycine max / Q000378:metabolism / Q000502:physiology*; D013696:Temperature
D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll; D000077194:Chlorophyll A