Functional Characterization of Herbaceous Peony PTC52 Gene Under High Temperature Stress

High temperature stress severely compromises plant growth and productivity by triggering chlorophyll loss. Plant protochlorophyllide-dependent translocon component of 52 kDa (PTC52) has been proven to be involved in chlorophyll biosynthesis, yet its functional role in plant high-temperature stress response remains uncharacterized. In our study, PlPTC52 was isolated and characterized from herbaceous peony (Paeonia lactiflora Pall.), an economically important ornamental species susceptible to high temperature stress. The PlPTC52 gene comprised a 1647 bp coding sequence that translates into a 548-amino-acid protein. Subcellular localization confirmed its chloroplast localization, consistent with its putative role in chlorophyll biosynthesis. Functional analyses showed that silencing of PlPTC52 in P. lactiflora accelerated chlorophyll loss, increased reactive oxygen species accumulation, and impaired photosystem II efficiency and membrane integrity under high temperature stress. Conversely, overexpression of PlPTC52 in Nicotiana tabacum decelerated chlorophyll loss, decreased reactive oxygen species accumulation, and improved photosystem II efficiency and membrane integrity under high temperature stress. Collectively, this study provides the first functional evidence implicating PTC52 in plant responses to high temperature stress and identifies PlPTC52 as a potential genetic resource for enhancing thermotolerance in horticultural crops.