PHYTOALEXIN DEFICIENT4 affects reactive oxygen species metabolism, cell wall and wood properties in hybrid aspen (Populus tremulaL.×tremuloides)

• Published in: Plant, cell and environment cell and environment, 2015-07, Vol.38 (7), p.1275
• Main Authors: Lesak, IRENEUSZ, SZECHYASKA-HEBDA, MAGDALENA, Fedak, HALINA, Sidoruk, NATALIA, DBROWSKA-BRONK, JOANNA, Witoa, DAMIAN, Rusaczonek, ANNA, Antczak, ANDRZEJ, Drodek, MICHA, Karpiaska, BARBARA, Karpiaski, STANISAW
• Format: Article
• Language: English
• Subjects: Hydrogen peroxide; Leaves; Manganese; Mortality; Photochemicals; Woody plants
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.12388

The PHYTOALEXIN DEFICIENT4 (PAD4) gene in Arabidopsis thaliana (AtPAD4) is involved in the regulation of plant - pathogen interactions. The role of PAD4 in woody plants is not known; therefore, we characterized its function in hybrid aspen and its role in reactive oxygen species (ROS)-dependent signalling and wood development. Three independent transgenic lines with different suppression levels of poplar PAD expression were generated. All these lines displayed deregulated ROS metabolism, which was manifested by an increased H2O2 level in the leaves and shoots, and higher activities of manganese superoxide dismutase (MnSOD) and catalase (CAT) in the leaves in comparison to the wild-type plants. However, no changes in non-photochemical quenching (NPQ) between the transgenic lines and wild type were observed in the leaves. Moreover, changes in the ROS metabolism in the pad4 transgenic lines positively correlated with wood formation. A higher rate of cell division, decreased tracheid average size and numbers, and increased cell wall thickness were observed. The results presented here suggest that the Populus tremula×tremuloidesPAD gene might be involved in the regulation of cellular ROS homeostasis and in the cell division - cell death balance that is associated with wood development. The PHYTOALEXIN DEFICIENT 4 (PAD4) gene is well-known positive regulator of the cell death in Arabidopsis and its function is important in control of integrated abiotic and biotic stress responses. But its function in woody plants is not known. Therefore, we selected transgenic hybrid aspen with reduced or suppressed PAD4 poplar ortholog expression. Our field study demonstrated that the P. tremula x tremuloidesPAD gene might be a negative regulator of the cell death and is involved in the regulation of the cellular ROS signalling homeostasis, wood development and cell wall properties.