Interplay of SLIM1 and miR395 in the regulation of sulfate assimilation in Arabidopsis

The Plant Journal (Impact Factor: 6.58). 04/2011; 66(5):863 - 876. DOI: 10.1111/j.1365-313X.2011.04547.x

ABSTRACT MicroRNAs play a key role in the control of plant development and response to adverse environmental conditions. For example, microRNA395 (miR395), which targets three out of four isoforms of ATP sulfurylase, the first enzyme of sulfate assimilation, as well as a low-affinity sulfate transporter, SULTR2;1, is strongly induced by sulfate deficiency. However, other components of sulfate assimilation are induced by sulfate starvation, so that the role of miR395 is counterintuitive. Here, we describe the regulation of miR395 and its targets by sulfate starvation. We show that miR395 is important for the increased translocation of sulfate to the shoots during sulfate starvation. MiR395 together with the SULFUR LIMITATION 1 transcription factor maintain optimal levels of ATP sulfurylase transcripts to enable increased flux through the sulfate assimilation pathway in sulfate-deficient plants. Reduced expression of ATP sulfurylase (ATPS) alone affects both sulfate translocation and flux, but SULTR2;1 is important for the full rate of sulfate translocation to the shoots. Thus, miR395 is an integral part of the regulatory circuit controlling plant sulfate assimilation with a complex mechanism of action.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: MicroRNA395 (miR395) is a conserved miRNA that targets a low-affinity sulfate transporter (AST68) and three ATP sulfurylases (APS1, APS3 and APS4) in higher plants. In this study, At2g28780 was confirmed as another target of miR395 in Arabidopsis. Interestingly, several dicots contained genes homologous to At2g28780 and a cognate miR395 complementary site but possess a gradient of mismatches at the target site. It is well-established that miR395 is induced during S deprivation in Arabidopsis; however, the signaling pathways that mediate this regulation are unknown. Several findings in the present study demonstrate that redox signaling plays an important role in induction of miR395 during S deprivation. These include the following results: (1) GSH supplementation suppressed miR395 induction in S-deprived plants; (2) miR395 is induced in Arabidopsis seedlings exposed to Arsenate or Cu(2+) , which induces oxidative stress; (3), S deprivation induced oxidative stress, and (4) compromised induction of miR395 during S deprivation in cad2 mutants (deficient in GSH biosynthesis) that is defective in glutaredoxin-dependent redox signaling and ntra/ntrb (defective in thioredoxin reductases a and b) double mutants that are defective in thioredoxin-dependent redox signaling. Collectively, these findings strongly support the involvement of redox signaling in inducing the expression of miR395 during S deprivation in Arabidopsis. This article is protected by copyright. All rights reserved.
    The Plant Journal 10/2013; · 6.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nitrate (NO3 (-) ) is a key signal molecule in plant metabolism and development, besides its role as a nutrient. It is known that Arabidopsis ANR1 is a major component in the NO3 (-) -signaling pathway triggering lateral root growth and miR444 which is specific to monocots targets four genes homologous to ANR1 in rice. Here, we show that miR444a plays multiple roles in the rice NO3 (-) -signaling pathway not only in root development, but also involving in nitrate accumulation and even in Pi starvation responses. miR444a overexpression resulted in reduced rice lateral root elongation, but promotion of rice primary and adventitious root growth, in a nitrate-dependent manner. In addition, overexpression of miR444a improved nitrate accumulation and expression of nitrate transporter genes under high nitrate concentration condition, but reduced the remobilization of nitrate from old leaves to young leaves thus affecting the plant adaptability to nitrogen limitation. Intriguingly, we found that Pi starvation strongly induced miR444 accumulation in rice roots and overexpression of miR444a altered Pi starvation-induced root architecture and enhanced Pi accumulation and expression of three Pi transporter genes. We further provided evidence that miR444a was involved in the interaction between the NO3 (-) - and Pi -signaling pathways in rice. Taken together, our observations demonstrate that miR444a plays multiple roles in the rice NO3 (-) -signaling pathway in nitrate-dependent root growth, nitrate accumulation and phosphate starvation responses. This article is protected by copyright. All rights reserved.
    The Plant Journal 01/2014; · 6.58 Impact Factor
  • Source


Available from
May 22, 2014