TY - JOUR

T1 - Chlorophyll fluorescence imaging analysis for elucidating the mechanism of photosystem II acclimation to cadmium exposure in the hyperaccumulating plant Noccaea caerulescens

AU - Bayçu, Gülriz

AU - Moustaka, Julietta

AU - Gevrek, Nurbir

AU - Moustakas, Michael

PY - 2018/12/18

Y1 - 2018/12/18

N2 - We provide new data on the mechanism of Noccaea caerulescens acclimation to Cd exposure by elucidating the process of photosystem II (PSII) acclimation by chlorophyll fluorescence imaging analysis. Seeds from the metallophyte N. caerulescens were grown in hydroponic culture for 12 weeks before exposure to 40 and 120 μM Cd for 3 and 4 days. At the beginning of exposure to 40 μM Cd, we observed a spatial leaf heterogeneity of decreased PSII photochemistry, that later recovered completely. This acclimation was achieved possibly through the reduced plastoquinone (PQ) pool signaling. Exposure to 120 μM Cd under the growth light did not affect PSII photochemistry, while under high light due to a photoprotective mechanism (regulated heat dissipation for protection) that down-regulated PSII quantum yield, the quantum yield of non-regulated energy loss in PSII (Φ NO ) decreased even more than control values. Thus, N. caerulescens plants exposed to 120 μM Cd for 4 days exhibited lower reactive oxygen species (ROS) production as singlet oxygen ( 1 O 2 ). The response of N. caerulescens to Cd exposure fits the 'Threshold for Tolerance Model', with a lag time of 4 d and a threshold concentration of 40 μM Cd required for the induction of the acclimation mechanism.

AB - We provide new data on the mechanism of Noccaea caerulescens acclimation to Cd exposure by elucidating the process of photosystem II (PSII) acclimation by chlorophyll fluorescence imaging analysis. Seeds from the metallophyte N. caerulescens were grown in hydroponic culture for 12 weeks before exposure to 40 and 120 μM Cd for 3 and 4 days. At the beginning of exposure to 40 μM Cd, we observed a spatial leaf heterogeneity of decreased PSII photochemistry, that later recovered completely. This acclimation was achieved possibly through the reduced plastoquinone (PQ) pool signaling. Exposure to 120 μM Cd under the growth light did not affect PSII photochemistry, while under high light due to a photoprotective mechanism (regulated heat dissipation for protection) that down-regulated PSII quantum yield, the quantum yield of non-regulated energy loss in PSII (Φ NO ) decreased even more than control values. Thus, N. caerulescens plants exposed to 120 μM Cd for 4 days exhibited lower reactive oxygen species (ROS) production as singlet oxygen ( 1 O 2 ). The response of N. caerulescens to Cd exposure fits the 'Threshold for Tolerance Model', with a lag time of 4 d and a threshold concentration of 40 μM Cd required for the induction of the acclimation mechanism.

KW - Cd toxicity

KW - Detoxification mechanism

KW - Photochemical quenching

KW - Photoprotective mechanism

KW - Photosynthetic heterogeneity

KW - Phytoremediation

KW - Plastoquinone pool

KW - Redox state

KW - Spatiotemporal variation

UR - http://www.scopus.com/inward/record.url?scp=85058680729&partnerID=8YFLogxK

U2 - 10.3390/ma11122580

DO - 10.3390/ma11122580

M3 - Journal article

C2 - 30567339

AN - SCOPUS:85058680729

VL - 11

SP - 1

EP - 14

JO - Materials Transactions

JF - Materials Transactions

SN - 1345-9678

IS - 12

M1 - 2580

ER -