Peroxisomal APX knockdown triggers antioxidant mechanisms favourable for coping with high photorespiratory H2O2 induced by CAT deficiency in rice
Rachel HV Sousa, Fabricio EL Carvalho, Carol W Ribeiro, Gisele Passaia, Juliana R Cunha, Yugo Lima-Melo, Márcia Margis-Pinheiro, Joaquim AG Silveira
https://urn.fi/URN:NBN:fi-fe2021042717382
Tiivistelmä
The physiological role of peroxisomal ascorbate
peroxidases (pAPX) is unknown; therefore, we utilized pAPX4 knockdown rice and
catalase (CAT) inhibition to assess its role in CAT compensation under high
photorespiration. pAPX4 knockdown induced co-suppression in the expression of pAPX3.
The rice mutants exhibited metabolic changes such as lower CAT and glycolate
oxidase (GO) activities and reduced glyoxylate content; however, APX activity
was not altered. CAT inhibition triggered different changes in the expression
of CAT, APX and glutathione peroxidase (GPX) isoforms between non-transformed
(NT) and silenced plants. These responses were associated with alterations in
APX, GPX and GO activities, suggesting redox homeostasis differences. The
glutathione oxidation-reduction states were modulated differently in mutants,
and the ascorbate redox state was greatly affected in both genotypes. The pAPX
suffered less oxidative stress and photosystem II (PSII) damage and displayed
higher photosynthesis than the NT plants. The improved acclimation exhibited by
the pAPX plants was indicated by lower H2O2 accumulation, which was associated with
lower GO activity and glyoxylate content. The suppression of both pAPXs and/or
its downstream metabolic and molecular effects may trigger favourable
antioxidant and compensatory mechanisms to cope with CAT deficiency. This physiological
acclimation may involve signalling by peroxisomal H2O2, which minimized the
photorespiration.
Kokoelmat
- Rinnakkaistallenteet [19207]