Phosphate sensing in higher plants

Abel, Steffen; Ticconi, Carla A.; Delatorre, Carla Andréa

doi:10.1034/j.1399-3054.2002.1150101.x

Cited by 302 publications

(251 citation statements)

References 53 publications

(100 reference statements)

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“…34 and 35). Pi limitation reduces primary root growth by attenuating cell division and promoting lateral root density and length, root architecture changes that are considered to facilitate Pi acquisition (3,34). These results indicate that AtSIZ1 is a negative regulator of Pi starvation-dependent signaling that controls root architecture and anthocyanin accumulation.…”

Section: Discussionmentioning

confidence: 68%

The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses

Miura

Rus

Sharkhuu

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

556

629

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Plants sense phosphate (Pi) deficiency and initiate signaling that controls adaptive responses necessary for Pi acquisition. Herein, evidence establishes that AtSIZ1 is a plant small ubiquitin-like modifier (SUMO) E3 ligase and is a focal controller of Pi starvation-dependent responses. T-DNA insertional mutated alleles of AtSIZ1 (At5g60410) cause Arabidopsis to exhibit exaggerated prototypical Pi starvation responses, including cessation of primary root growth, extensive lateral root and root hair development, increase in root/shoot mass ratio, and greater anthocyanin accumulation, even though intracellular Pi levels in siz1 plants were similar to wild type. AtSIZ1 has SUMO E3 ligase activity in vitro, and immunoblot analysis revealed that the protein sumoylation profile is impaired in siz1 plants. AtSIZ1-GFP was localized to nuclear foci. Steadystate transcript abundances of Pi starvation-responsive genes AtPT2, AtPS2, and AtPS3 were moderate but clearly greater in siz1 seedlings than in wild type, where Pi is sufficient. Pi starvation induced the expression of these genes to the same extent in siz1 and wild-type seedlings. However, two other Pi starvation-responsive genes, AtIPS1 and AtRNS1, are induced more slowly in siz1 seedlings by Pi limitation. PHR1, a MYB transcriptional activator of AtIPS1 and AtRNS1, is an AtSIZ1 sumoylation target. These results indicate that AtSIZ1 is a SUMO E3 ligase and that sumoylation is a control mechanism that acts both negatively and positively on different Pi deficiency responses

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Section: Discussionmentioning

confidence: 68%

The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses

Miura

Rus

Sharkhuu

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

556

629

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“…Expression of class II RNases, including RNS2, is normally high in most tissues (3, 8, 30, 31); however, these class II RNases are induced by senescence and phosphate starvation in plants (6,30). It was proposed that these enzymes, along with several class I RNase T2 enzymes that are also induced by starvation, are part of a phosphate-scavenging system that rescues plants under nutritional stress (9). It is possible that a ribophagylike mechanism also participates in this scavenging system.…”

Section: Discussionmentioning

confidence: 99%

“…RNS2 expression is increased even further during senescence and during inorganic phosphate (Pi) starvation (6,8). Thus, it was hypothesized that RNS2 is part of a phosphate scavenging system that rescues plants that are under nutritional stress (9). However, because RNS2 and other class II RNase T2 proteins accumulate to high levels even under optimal growth conditions, this rescue function is unlikely to be the main role of these enzymes.…”

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confidence: 99%

RNS2, a conserved member of the RNase T2 family, is necessary for ribosomal RNA decay in plants

Hillwig

Contento

Meyer

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

136

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RNase T2 enzymes are conserved in most eukaryotic genomes, and expression patterns and phylogenetic analyses suggest that they may carry out an important housekeeping role. However, the nature of this role has been elusive. Here we show that RNS2, an intracellular RNase T2 from Arabidopsis thaliana, is essential for normal ribosomal RNA recycling. This enzyme is the main endoribonuclease activity in plant cells and localizes to the endoplasmic reticulum (ER), ER-derived structures, and vacuoles. Mutants lacking RNS2 activity accumulate RNA intracellularly, and rRNA in these mutants has a longer half-life. Normal rRNA turnover seems essential to maintain cell homeostasis because rns2 mutants display constitutive autophagy. We propose that RNS2 is part of a process that degrades rRNA to recycle its components. This process appears to be conserved in all eukaryotes. ribophagy R ibonucleases (RNases) belonging to the RNase T2 family are acidic endonucleases without base specificity that are either extracellular or targeted to the secretory pathway (1). This family is conserved in the genome of almost all eukaryotic organisms so far analyzed, suggesting that it performs an important function that has been maintained throughout evolution (2, 3). Phylogenetic analyses have identified three subclasses present in plant genomes (3, 4). Class I proteins are highly diversified and show evidence of gene sorting, and their expression is commonly tissue-specific and/or regulated by biotic and abiotic stress (3). Class III includes mostly members of the S-RNases, enzymes involved in the process of gametophytic self-incompatibility in three plant families (5). Finally, class II includes proteins that are highly conserved in all plant genomes and are normally expressed at high levels in most plant tissues (3). On the basis of their conservation and gene expression characteristics, we proposed that class II RNases may have a housekeeping role in plant cells (3). Similar gene expression and phylogenetic studies in animals led us to the hypothesis that metazoan RNase T2 enzymes also have a housekeeping role and may be equivalent to class II enzymes from plants (2).RNS2, one of five RNase T2 genes in the Arabidopsis genome, encodes the only class II protein in this model organism (3,4). This RNase is present in all tissues at high levels (6, 7) and is localized in an intracellular compartment. RNS2 expression is increased even further during senescence and during inorganic phosphate (Pi) starvation (6, 8). Thus, it was hypothesized that RNS2 is part of a phosphate scavenging system that rescues plants that are under nutritional stress (9). However, because RNS2 and other class II RNase T2 proteins accumulate to high levels even under optimal growth conditions, this rescue function is unlikely to be the main role of these enzymes. Moreover, in vertebrates, in which RNase T2 enzymes are absolutely conserved (2), the mechanisms that control the response to phosphate starvation seem to be specific to the intestine and kidney (10), wherea...

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“…In response to low P availability in the soil, plants have developed several adaptive strategies to increase P acquisition, including enhanced expression of P transport genes, exudation of P-solubilizing substances, such as organic acids and phosphatases, and alterations in postembryonic root development (for review, see Raghothama, 1999;Ló pez-Bucio et al, 2000;Abel et al, 2002;Ló pez-Bucio et al, 2003;Vance et al, 2003).…”

mentioning

confidence: 99%

An Auxin Transport Independent Pathway Is Involved in Phosphate Stress-Induced Root Architectural Alterations in Arabidopsis. Identification of BIG as a Mediator of Auxin in Pericycle Cell Activation

et al. 2005

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Arabidopsis (Arabidopsis thaliana) plants display a number of root developmental responses to low phosphate availability, including primary root growth inhibition, greater formation of lateral roots, and increased root hair elongation. To gain insight into the regulatory mechanisms by which phosphorus (P) availability alters postembryonic root development, we performed a mutant screen to identify genetic determinants involved in the response to P deprivation. Three low phosphate-resistant root lines (lpr1-1 to lpr1-3) were isolated because of their reduced lateral root formation in low P conditions. Genetic and molecular analyses revealed that all lpr1 mutants were allelic to BIG, which is required for normal auxin transport in Arabidopsis. Detailed characterization of lateral root primordia (LRP) development in wild-type and lpr1 mutants revealed that BIG is required for pericycle cell activation to form LRP in both high (1 mM) and low (1 mM) P conditions, but not for the low P-induced alterations in primary root growth, lateral root emergence, and root hair elongation. Exogenously supplied auxin restored normal lateral root formation in lpr1 mutants in the two P treatments. Treatment of wild-type Arabidopsis seedlings with brefeldin A, a fungal metabolite that blocks auxin transport, phenocopies the root developmental alterations observed in lpr1 mutants in both high and low P conditions, suggesting that BIG participates in vesicular targeting of auxin transporters. Taken together, our results show that auxin transport and BIG function have fundamental roles in pericycle cell activation to form LRP and promote root hair elongation. The mechanism that activates root system architectural alterations in response to P deprivation, however, seems to be independent of auxin transport and BIG.

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Phosphate sensing in higher plants

Cited by 302 publications

References 53 publications

The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses

The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses

RNS2, a conserved member of the RNase T2 family, is necessary for ribosomal RNA decay in plants

An Auxin Transport Independent Pathway Is Involved in Phosphate Stress-Induced Root Architectural Alterations in Arabidopsis. Identification of BIG as a Mediator of Auxin in Pericycle Cell Activation

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