SIZ1 Regulation of Phosphate Starvation-Induced Root Architecture Remodeling Involves the Control of Auxin Accumulation      

Abstract

Phosphate (Pi) limitation causes plants to modulate the architecture of their root systems to facilitate the acquisition of Pi. Previously, we reported that the Arabidopsis (Arabidopsis thaliana) SUMO E3 ligase SIZ1 regulates root architecture remodeling in response to Pi limitation; namely, the siz1 mutations cause the inhibition of primary root (PR) elongation and the promotion of lateral root (LR) formation. Here, we present evidence that SIZ1 is involved in the negative regulation of auxin patterning to modulate root system architecture in response to Pi starvation. The siz1 mutations caused greater PR growth inhibition and LR development of seedlings in response to Pi limitation. Similar root phenotypes occurred if Pi-deficient wild-type seedlings were supplemented with auxin. N-1-Naphthylphthalamic acid, an inhibitor of auxin efflux activity, reduced the Pi starvationinduced LR root formation of siz1 seedlings to a level equivalent to that seen in the wild type. Monitoring of the auxinresponsive reporter DR5::uidA indicated that auxin accumulates in PR tips at early stages of the Pi starvation response. Subsequently, DR5::uidA expression was observed in the LR primordia, which was associated with LR elongation. The timesequential patterning of DR5::uidA expression occurred earlier in the roots of siz1 as compared with the wild type. In addition, microarray analysis revealed that several other auxin-responsive genes, including genes involved in cell wall loosening and biosynthesis, were up-regulated in siz1 relative to wild-type seedlings in response to Pi starvation. Together, these results suggest that SIZ1 negatively regulates Pi starvation-induced root architecture remodeling through the control of auxin patterning.

Defining the SUMO System in Maize: SUMOylation Is Up-Regulated during Endosperm Development and Rapidly Induced by Stress

“…7; Supplemental Fig. S15), consistent with the importance of SUMOylation to floral timing, reproductive tissue development, and embryogenesis (Miura et al, 2011).…”

Biotechnology of nutrient uptake and assimilation in plants

“…Interestingly, in null mutants of the AtSIZ1 (a positive regulator of PHR1 activity by sumoylation) gene, a root phenotype similar to that described for PHR2-overexpressing plants was associated with changes in auxin accumulation (Miura et al, 2011). Although SIZ1 and PHR1 are components of the same signaling pathway that regulate many responses to Pi deficiency, these molecular controllers might play opposite roles on root development (Miura et al, 2011).…”

SlICE1 encoding a MYC-type transcription factor controls cold tolerance in tomato, Solanum lycopersicum

“…PCR products were detected by ermal Cycler Dice Real Time System (Takara Bio Inc., Kyoto, Japan). Relative di erences in expression were calculated as described previously (Miura et al 2011b;Miura et al 2011c). Brie y, relative transcript abundance was calculated using the comparative C T method (User Bulletin 2 for ABI PRISM 7700 sequence detection systems).…”