Transcripts of MYB-like genes respond to phosphorous and nitrogen deprivation in Arabidopsis

Abstract

In Arabidopsis thaliana (L.) Heynh., AtPhr2 and AtNsr1 encode proteins with MYB-like and alpha-helical domains. They resemble CrPsr1, a nuclear-localized MYB protein that is critical for acclimation to phosphorous (P) starvation in the alga Chlamydomonas reinhardtii. Reverse transcription-polymerase chain reaction analysis of the first unique exons indicated that AtPhr2 mRNA increased as early as 6 h after P deprivation (-P), whereas nitrogen deprivation (-N) had no effect. The AtNsr1 mRNA level increased exclusively under -N, an increase first noted by 2 days in -N. In spite of P- and N-specific effects on expression of AtPhr2 and AtNsr1 there appeared to be P-N cross-talk at the whole-plant level. Total non-secreted acid phosphatase activity increased under both -P and -N within 2 days of deprivation. Further, the pho2-1/pho2-1 mutant, reported to be a phosphate accumulator, showed no increase in AtPhr2 mRNA in response to -P and a 70% reduction in the response of AtNsr1 mRNA to -N. Consistent with this pattern, there was no increase in acid phosphatase activity in pho2-1/pho2-1 plants deprived of P or N. However, when deprived of P, pho2-1/pho2-1 plants accumulated much higher levels of nitrate. T-DNA disruption of AtNsr1 resulted in altered expression of at least one nitrate transporter (AtNRT2.5). Further evidence of cross-talk between N and P responses was altered expression of N-responsive genes in pho2-1/pho2-1.

Phosphorus Stress in Common Bean: Root Transcript and Metabolic Responses

“…The induction of Arabidopsis MYB TF genes in response to different biotic stresses (Chen et al, 2002) and to P starvation (Mü ller et al, 2007) has been shown previously. It has been demonstrated that the Arabidopsis PHR1 and PHR2 genes, which resemble the PSR1 gene from Chlamydomonas reinhardtii and belong to the TF MYB superfamily, are crucial for P starvation signaling Todd et al, 2004). Our BLAST analysis revealed that the deduced translated amino acid sequence of MYB TF TC2883, induced 2-fold in 2P roots (Table III), showed 59% amino acid identity to PHR1 (BLASTX E value 5 4.1E…”

Similarities and Differences in the Acquisition of Fe and P by Dicot Plants

“…Other physiological responses are the increased synthesis and release of organic acids, the up-regulation of ribonucleases, the accumulation of starch and anthocyanins, and the remobilization of internal phosphate [37][38][39]. The regulation of the physiological responses to P deficiency is not fully understood but in Arabidopsis thaliana L. it has been demonstrated that AtPHR1 and AtPHR2 ("Phosphate Starvation Response" 1 and 2, respectively), which encode transcription factors of the MYB family are crucial for signaling P deficiency [40][41][42][43][44]. Among the morphological responses to P deficiency are an increase in the root/shoot ratio [45,46] and changes in the root system architecture that is able to absorb more phosphate, by reducing the growth of the primary root and promoting the appearance of secondary roots with a large amount of root hairs [45,47,48].…”

Genome-Wide Analysis of the Arabidopsis Leaf Transcriptome Reveals Interaction of Phosphate and Sugar Metabolism

“…These are the MYB family proteins, PSR1 from Chlamydomonas reinhardtii (Wykoff et al, 1999;Moseley et al, 2006) and PHR1 from Arabidopsis (Rubio et al, 2001). Two more related transcription factors appear to be associated with nutrient stress responses (Todd et al, 2004), and these factors belong to a family of 15 genes with homology to PHR1. In this study, none of the genes in this family, including PHR1, responded to P starvation.…”