TY - JOUR
T1 - Photosystem II photochemistry and its sensitivity to heat stress in maize plants as affected by nitrogen deficiency
AU - Lu, Cong Ming
AU - Zhang, Jian Hua
N1 - Funding Information:
We are grateful to Hong Kong Baptist University (FRG grant) and the Croucher Foundation for their financial support to this study.
PY - 2000/7
Y1 - 2000/7
N2 - Effects of nitrogen deficiency on photosystem II photochemistry and its sensitivity of heat stress (25-44 °C) were investigated in maize plants (Zea mays L.) grown under natural illumination. Maize plants were fertilized with 15 mmol/L nitrate (high N, control) versus 0.5 mmol/L nitrate (low N, N deficiency). Compared with the high-N plants, the low-N plants had lower values in the apparent quantum yield of photosynthesis and light-saturated CO2 assimilation capacity expressed either on a basis of leaf area or chlorophyll. In the light-adapted state, the low-N plants showed substantial decreases in the quantum yield of PSII electron transport (Φ(PSII), 28 %), the efficiency of excitation energy capture by open PSII reaction centers (F(v)'/F(m)', 12 %) and the photochemical quenching coefficient (q(p), 19 %), as well as a significant increase in the non-photochemical quenching coefficient (q(N), 84 %). In the dark-adapted state, the low-N plants showed a small but a significant decrease (4 %) in the maximal efficiency of PSII photochemistry (F(v)/F(m)). These results suggest that N deficiency induced no substantial damage to PSII apparatus and the changes in PSII photochemistry in the light-adapted state can be seen as a regulatory response to down-regulate the quantum yield of PSII electron transport (Φ(PSII)) that would match with the decreased CO2 assimilation rate under N deficiency conditions. When exposed to high temperatures, a greater decrease in Φ)PSII), F(v)'/F(m)' and q(p), as well as a larger increase in q(N) and the proportion of the Q(B)-non-reducing PSII reaction centers were observed in the low-N plants than in the high-N plants, indicating that the responses of PSII to heat stress was significantly affected by N status, with N deficiency increasing the sensitivity of PSII to heat stress. These results suggest that nitrogen nutrition plays an important role in the protective adaptation of PSII to heat stress.
AB - Effects of nitrogen deficiency on photosystem II photochemistry and its sensitivity of heat stress (25-44 °C) were investigated in maize plants (Zea mays L.) grown under natural illumination. Maize plants were fertilized with 15 mmol/L nitrate (high N, control) versus 0.5 mmol/L nitrate (low N, N deficiency). Compared with the high-N plants, the low-N plants had lower values in the apparent quantum yield of photosynthesis and light-saturated CO2 assimilation capacity expressed either on a basis of leaf area or chlorophyll. In the light-adapted state, the low-N plants showed substantial decreases in the quantum yield of PSII electron transport (Φ(PSII), 28 %), the efficiency of excitation energy capture by open PSII reaction centers (F(v)'/F(m)', 12 %) and the photochemical quenching coefficient (q(p), 19 %), as well as a significant increase in the non-photochemical quenching coefficient (q(N), 84 %). In the dark-adapted state, the low-N plants showed a small but a significant decrease (4 %) in the maximal efficiency of PSII photochemistry (F(v)/F(m)). These results suggest that N deficiency induced no substantial damage to PSII apparatus and the changes in PSII photochemistry in the light-adapted state can be seen as a regulatory response to down-regulate the quantum yield of PSII electron transport (Φ(PSII)) that would match with the decreased CO2 assimilation rate under N deficiency conditions. When exposed to high temperatures, a greater decrease in Φ)PSII), F(v)'/F(m)' and q(p), as well as a larger increase in q(N) and the proportion of the Q(B)-non-reducing PSII reaction centers were observed in the low-N plants than in the high-N plants, indicating that the responses of PSII to heat stress was significantly affected by N status, with N deficiency increasing the sensitivity of PSII to heat stress. These results suggest that nitrogen nutrition plays an important role in the protective adaptation of PSII to heat stress.
KW - Heat stress
KW - Maize (Zea mays L.)
KW - Nitrogen deficiency
KW - Photoinhibition
KW - Photosystem II
UR - http://www.scopus.com/inward/record.url?scp=0033865394&partnerID=8YFLogxK
U2 - 10.1016/S0176-1617(00)80145-5
DO - 10.1016/S0176-1617(00)80145-5
M3 - Journal article
AN - SCOPUS:0033865394
SN - 0176-1617
VL - 157
SP - 124
EP - 130
JO - Journal of Plant Physiology
JF - Journal of Plant Physiology
IS - 1
ER -