Functional analysis of and under low-phosphate stress in maize.

UNLABELLED

The PHOSPHATE STARVATION RESPONSE REGULATOR (PHR) plays a crucial regulatory role in plants during the process of responding to phosphate starvation. In this study, we combined reverse genetics and biotechnology to investigate the function of and , including proteins containing the Myb_DNA_banding and Myb_CC-LHEQLE structural domains, in maize seedlings. Phylogenetic analysis revealed that and have high homology with and , and share the characteristic features of nuclear localisation and transcriptional self-activation. Real-time quantitative PCR analysis showed that low phosphate (Pi) stress significantly induced the expression of and in maize seedling stage, and candidate gene association analysis further revealed the close association of these two genes with root traits under Pi stress conditions. Transgenic plants overexpressing and in show a significant increase in lateral root number, fresh weight and total phosphorus accumulation under low-Pi stress. Besides, CHIP-PCR experiments identified target genes involved in hormone regulation, metal ion transport and homeostasis, phosphatase encoding, and photosynthesis, providing new insights into the biological functions of and . Furthermore, our study showed that ZmPHR1 interacts with six SPX domain-only proteins (ZmSPXs) in maize, while ZmPHR2 interacts with five of these proteins. and expression was repressed in low Pi conditions, but was up-regulated in knockout material, according to our study of transgenic seedlings overexpressing in maize. We identified downstream target genes involved in the phosphorus signaling pathway, which are mainly involved in plant-pathogen interactions, ascorbic acid and arabinose metabolism, and ABC transporter proteins, by RNA-seq analysis of transgenic seedlings grown under low Pi stress for 7 days. Collectively, these results provide important clues to elucidate the role and functional significance of and under low Pi stress and also provide insights into understand the molecular mechanism of phosphorus homeostasis in maize.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11032-024-01508-2.