Analysis of Arabidopsisglucose insensitive growthMutants Reveals the Involvement of the Plastidial Copper Transporter PAA1 in Glucose-Induced Intracellular Signaling    

Abstract

Sugars play important roles in many aspects of plant growth and development, acting as both energy sources and signaling molecules. With the successful use of genetic approaches, the molecular components involved in sugar signaling have been identified and their regulatory roles in the pathways have been elucidated. Here, we describe novel mutants of Arabidopsis (Arabidopsis thaliana), named glucose insensitive growth (gig), identified by their insensitivity to high-glucose (Glc)-induced growth inhibition. The gig mutant displayed retarded growth under normal growth conditions and also showed alterations in the expression of Glc-responsive genes under high-Glc conditions. Our molecular identification reveals that GIG encodes the plastidial copper (Cu) transporter PAA1 (for P 1B -type ATPase 1). Interestingly, double mutant analysis indicated that in high Glc, gig is epistatic to both hexokinase1 (hxk1) and aba insensitive4 (abi4), major regulators in sugar and retrograde signaling. Under high-Glc conditions, the addition of Cu had no effect on the recovery of gig/paa1 to the wild type, whereas exogenous Cu feeding could suppress its phenotype under normal growth conditions. The expression of GIG/PAA1 was also altered by mutations in the nuclear factors HXK1, ABI3, and ABI4 in high Glc. Furthermore, a transient expression assay revealed the interaction between ABI4 and the GIG/PAA1 promoter, suggesting that ABI4 actively regulates the transcription of GIG/PAA1, likely binding to the CCAC/ACGT core element of the GIG/PAA1 promoter. Our findings indicate that the plastidial Cu transporter PAA1, which is essential for plastid function and/or activity, plays an important role in bidirectional communication between the plastid and the nucleus in high Glc.

Priming of Brachiaria Seeds With Different Sugar Sources and Concentrations

“…Corroborating the results of this study, Lee et al (2012) found no inhibition of root growth for Arabidopsis mutants when in the presence of 6% glucose. However, at 1% glucose, the results suggested a reduction in the cell division of the root meristem, which results in a delay in root growth.…”

“…Sugars play an important role as energy supply during seed germination (MARCOS-FILHO, 2015) and in plant growth and development as both energy sources and signaling molecules (LEE et al, 2012). While studying the germination of Arabidopsis sp.…”

ABI4 and its role in chloroplast retrograde communication

“…The developmental arrest in response to sugars only occurs during early developmental stages, similar to some of the retrograde chloroplast signaling responses (Dekkers et al, 2008). Sugars and ABA have been proposed to act as important signals during early development by directly controlling germination, photo-autotrophic development, the expression of photosynthetic genes (Baier and Dietz, 2005; Katagiri et al, 2005; Cottage et al, 2010; Lee et al, 2012) and even the initiation of plastid retrograde signaling (Koussevitzky et al, 2007). ABI4 also plays an important role in other plant functions including nitrogen signaling, lipid mobilization in the embryo, root growth, lateral root inhibition, and pathogen resistance (Signora et al, 2001; Jakab et al, 2005; Penfield et al, 2006; Kaliff et al, 2007; Shkolnik-Inbar and Bar-Zvi, 2010; Kerchev et al, 2011; Cui et al, 2012).…”

“…In in vitro and transient assays, ABI4 has been shown to bind to the CE1-like element CACCG, which is present in the promoters of its putative target genes in A. thaliana (Finkelstein et al, 1998; Niu et al, 2002; Sakuma et al, 2002; Acevedo-Hernandez et al, 2005; Koussevitzky et al, 2007; Bossi et al, 2009; Giraud et al, 2009; Yang et al, 2011; Lee et al, 2012) and maize (Hu et al, 2012). Binding to this sequence results in the activation or repression of target genes, including ABI4 itself (Acevedo-Hernandez et al, 2005; Rook et al, 2006b; Bossi et al, 2009).…”

Early generation of nitric oxide contributes to copper tolerance through reducing oxidative stress and cell death in hulless barley roots

“…Plants have evolved different strategies to counteract Cu toxicity, including the regulation of Cu exclusion, chelation, sequestration, and storage in the tissue (Burkhead et al 2009;Lee et al 2012;Benatti et al 2014;Shin et al 2012). Cu toxicity in plants is associated with the generation of large quantities of ROS (İşeri et al 2011;Xu et al 2011;Thounaojam et al 2012).…”