Arabidopsis gun4 mutant have greater light energy transfer efficiency in photosystem II despite low chlorophyll content

• Published in: Theoretical and experimental plant physiology Vol. 26; no. 3-4; pp. 177 - 187
• Main Authors: Daloso, Danilo de Menezes, Antunes, Werner Camargos, Santana, Téssio A., Pinheiro, Daniela Pereira, Ribas, Rogério Ferreira, Sachetto-Martins, Gilberto, Loureiro, Marcelo Ehlers
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-12-2014
• Subjects: Biomedical and Life Sciences; Life Sciences; Light energy transfer; Photosystem II; Light harvesting complex II; Light stress
• ISSN: 2197-0025; 2197-0025
• DOI: 10.1007/s40626-014-0025-z

Arabidopsis
gun4
mutant is defected in retrograde signaling and is characterized by reduced levels of chlorophyll. However, the impact of this mutation on plant photosynthetic performance remains unclear. We carried out a physiological characterization of
gun4
in order to investigate the role of GUN4 for plant photosynthetic performance under light stress. The
gun4
plants showed reduced minimal fluorescence in dark-adapted leaves and quantum yield of unregulated energy dissipation of photosystem II (PSII) under non-light-stress condition. The effective quantum yield of the PSII (Φ
PSII
) and photochemical quenching (qL) were higher in
gun4
plants. Higher values of Φ
PSII
were also observed in
gun4
under different light intensities. However, the rate of net carbon assimilation and stomatal conductance were lower in
gun4
. No differences were detected between the genotypes in the total absorption of
14
CO
2
as well as in the percentage of
14
C flux to basic amino acids, sugars, starch, and cell wall. After light stress, the potential quantum yield of PSII decreased only in wild type and the non-photochemical quenching was higher in
gun4
. Taken together, the results suggest that
gun4
transfers more efficiently the excess of light energy absorbed despite a reduction in chlorophyll and carotenoids content and has greater capacity to dissipate the excess of energy absorbed.