Genome-wide expression analysis reveals contrasting regulation of phosphate starvation response (PSR) in root and shoot of Arabidopsis and its association with biotic stress

Abstract Owing to the low mobility and solubility of phosphate (Pi), it is often found in deficient conditions in soil. To cope with deficiency, the rapid use of Pi fertilizer is endangering the limited source of phosphorus minerals. To address the issue, a deeper understanding of phosphate starvation response (PSR) in plants is warranted. We investigated the Arabidopsis transcriptome under deficient phosphate condition (P0), using a novel exon ST array Affymetrix chip to understand the global molecular mechanism(s) of PSR. The Pi deficiency creates a nutrient ion imbalance and expression of genes associated with maintenance of redox state, and Ca2+ signaling is upregulated, initiating the cascade of signaling, leading to a genome-wide adaptive response in root. Most of the transcription factors belonging to WRKY family were observed to be upregulated in root, suggesting a tissue-specific activator role. The AP2-EREBP family genes appear to act as a repressor in root. In contrast, the redox, Ca2+ signaling, and receptor kinase genes show modulated expression in shoot. The MYBs, bZIPs, and AP2-EREBPs family of transcription factors are upregulated and linked to secondary metabolite production in shoot. The Mapman analysis revealed the significant visibility of the genes under the biotic stress category in both root and shoot. Many unknown category genes upregulated by > 5-fold show their association with defense response to biotic stress. Therefore, a significant linkage of biotic stress response to the Pi starvation response is observed in root and shoot. Hence, this study offers a critical updated insight into PSR to increase Pi use efficiency in plants.