MONITORING PQ-POOL REDOX STATE BASED ON THE OJIP-TRANSIENT IN LEAVES OF
Sesbania virgata PLANTS UPON ORGANIC FERTILIZATION
MONTCHARLES DA SILVA PONTES1, ETENALDO FELIPE SANTIAGO1, MICHELE APARECIDA
DOS SANTOS NOBREGA1, JAQUELINE DA SILVA SANTOS1, YAOVI ABEL KISSI1, DANIELA
ESPANGUER GRACIANO2, ANDERSON RODRIGUES DE LIMA CAIRES3
1Plant Resources Study Group, Natural Resources Study Center, Universidade Estadual de Mato
Grosso do Sul, C.P. 351, Dourados, MS.
2Applied Optics Group, Laboratory of Biophotonics, Universidade Federal da Grande Dourados, C.P.
351, Dourados, MS.
3Optics and Photonics Group, Institute of Physics, Universidade Federal de Mato Grosso do Sul
Introduction: The plastoquinone (PQ) pool forms the utilitarian association between photosystems II
(PSIIs) and cytochrome b6/f-complexes in the photosynthetic electron transport. In addition, PQ-pool
redox state assumes an important role in the regulation of several photochemical processes and, can
be monitored by using chlorophyll fluorescence (OJIP-transient) [1]. OJIP-transient has proved to be a
convenient method to determine the PSII electron flow, as well as, photochemical energy dissipation
in PSII can be conveniently studied by the behavior of OJIP-transient [2]. We hypothesize that the
acclimation period after fertilization is relevant to planting check nutritional responses. Aim: Here, we
aimed to contribute to the current knowledge concerning the organic fertilization effects in PSII
electron flow regulation by examining Sesbania virgata plants by using chlorophyll fluorescence OJIPtransient technique. Material and methods: Leaflets OJIP-transient was measured using a portable
fluorometer FluorPen FP-100 PSI (Photon Systems Instruments). Data obtained by evaluating the
chlorophyll fluorescence transient was recorded from 0 ms to 1s. Was assessed from readings taken
between 8 and 10 a.m., for 1, 4, 15 and 20 days after nutritional acclimation, on mature leaflets fully
expanded of the 3rd node, whereby the instantaneous parameter were obtained. Results and
discussion: The parameters F20μs (initial fluorescence) and FJ (2ms) were used as potential indicators
of the redox state of the PQ-pool (Figure 1a-d), the relationship between FJ and the F20μs values is
shown. The relationship between the two parameters was linear and, the F20 ls-value would be
affected by connectivity during acclimation period after fertilization. Time course of OJIP-transient is
shown (Figure 1e-d) this suggests a photochemical adjustment in dark-adapted leaves of Sesbania
virgata plants. These observations suggest that the adjustment represents the reduction of the PSII
acceptor side (reduction of QA and QB) are affected in the same way by changes in the PQ-pool redox
state [1]. Conclusions: The studied plant species exhibit adjustments during nutritional acclimation
period probed by OJIP-transient.
Figure 1: The F20μs-values plotted as a function of FJ and OJIP-transient of Sesbania
virgata plants upon organic fertilization.
References
[1] S. Z. Tòth, G. Schansker, R. J. Strasser, Photosynth. Res 93 (2007) 193–203.
[2] E. F. Santiago, T. C. Larentis, V. M. Barbosa, A. R. L. Caires, G. A. Moraes, Y. R. Súarez, J.
Fluoresc 25 (2015) 49–57.
Key-words: Electron transport; OJIP-transient; photosynthesis; plastoquinone pool.
Acknowledgment: FUNDECT/MS, UEMS.
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