BPM Proteins Modulate Heat Stress Response in Seedlings.

Plant responses to heat stress include complex transcriptional networks and protein regulations in which BTB/POZ-MATH (BPM) proteins participate as a part of ubiquitin-mediated protein degradation. contains six genes involved in responses to environmental changes, including heat. Seedlings overexpressing (), seedlings with downregulation of , , , and () and wild type were exposed to 37 °C for 6 h. Treatment caused stronger decline of photosynthesis in than in and wild type, although all seedlings recovered after 24 h at 24 °C. The activity of the antioxidant enzymes catalase, guaiacol peroxidase, and ascorbate peroxidase remained unchanged in , but increased in and wild type. Heat stress induced HSP70 and HSP90 in all seedlings but expression remained notably higher in after recovery. and expression increased in all seedlings immediately after stress, with the strongest induction in . In and wild type, expression was induced immediately after exposure, while , , , and were upregulated in wild type after recovery. In seedlings, expression decreased and expression increased immediately after treatment at 37 °C for 6 h. The results suggest that BPM proteins modulate heat stress response by influencing photosynthesis, activation of antioxidant enzymes, accumulation of HSPs, and expression of heat-responsive genes, thus contributing to the different physiological strategies observed in . lines with altered expression of genes.