The homeodomain (PHD) protein, PdbPHD3, confers salt tolerance by regulating squamosa promoter binding protein PdbSBP3 in Populus davidiana × P. bolleana

• Published in: Plant physiology and biochemistry Vol. 216; p. 109128
• Main Authors: Cao, Yanting, Guo, Huiyan, Liu, Zhujun, Wang, Chao, Wang, Yucheng
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.11.2024
• Subjects: ChIP-seq; Gene expression; Homeodomain (PHD) protein; Populus davidiana × P. bolleana; Salt stress; Squamosa promoter binding (SBP) protein; ChIP-seq; Homeodomain (PHD) protein; Salt stress; Gene expression; Populus davidiana × P. bolleana; Squamosa promoter binding (SBP) protein
• ISSN: 0981-9428; 1873-2690; 1873-2690
• DOI: 10.1016/j.plaphy.2024.109128

Plant homeodomain (PHD) proteins are a family of zinc finger transcription factors that play roles in abiotic stress tolerance. However, their mechanisms in conferring salt tolerance are largely unknown. In this study, we characterized a PHD gene, PdbPHD3, from Populus davidiana × P. bolleana (Shanxin poplar) in response to salt stress. PdbPHD3 is a nuclear protein that is strongly induced by salt and abscisic acid (ABA) treatments. Overexpression of PdbPHD3 conferred salt tolerance, while silencing of PdbPHD3 increased sensitivity to salt. PdbPHD3 could enhance the activities of superoxide dismutase and peroxidase to reduce the abundance of reactive oxygen species, and enhance the osmotic potential by increasing the proline content. Chromatin immunoprecipitation sequencing (ChIP-seq) revealed that PdbPHD3 could bind to various DNA motifs, including the G-box (“CACGTG”), PALBOXAPC (“GGACGG”), and POLLEN1LELAT52 (“TTTCTT”). ChIP-seq combined with RNA sequencing identified a transcription factor gene, squamosa promoter binding protein 3 (PdbSBP3), which is directly regulated by PdbPHD3. Overexpression and silencing of PdbSBP3 improved and decreased salt tolerance, respectively. PdbSBP3 could also regulate all the physiological changes associated with salt tolerance, similar to PdbPHD3. These results suggest that PdbPHD3 confers salt tolerance by regulating PdbSBP3 to reduce ROS accumulation and increase proline content. Therefore, the regulatory axis of PdbPHD3 and PdbSBP3 confers salt tolerance in Shanxin poplar. •PdbPHD3 binds to G-box motif to induce the expression of PdbSBP3.•PdbSBP3 confers salt tolerance by reducing ROS accumulation and enhancing proline contents.•Salt stress induces PdbPHD3, and PdbPHD3 activates PdbSBP3 to confers salt tolerance.•PdbPHD3-PdbSBP3 regulatory pathway responding to salt is revealed in Shanxin poplar.