The Transcription Factor ABI4 Is Required for the Ascorbic Acid–Dependent Regulation of Growth and Regulation of Jasmonate-Dependent Defense Signaling Pathways inArabidopsis   

Abstract

Cellular redox homeostasis is a hub for signal integration. Interactions between redox metabolism and the ABSCISIC ACID-INSENSITIVE-4 (ABI4) transcription factor were characterized in the Arabidopsis thaliana vitamin c defective1 (vtc1) and vtc2 mutants, which are defective in ascorbic acid synthesis and show a slow growth phenotype together with enhanced abscisic acid (ABA) levels relative to the wild type (Columbia-0). The 75% decrease in the leaf ascorbate pool in the vtc2 mutants was not sufficient to adversely affect GA metabolism. The transcriptome signatures of the abi4, vtc1, and vtc2 mutants showed significant overlap, with a large number of transcription factors or signaling components similarly repressed or induced. Moreover, lincomycin-dependent changes in LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN 1.1 expression were comparable in these mutants, suggesting overlapping participation in chloroplast to nucleus signaling. The slow growth phenotype of vtc2 was absent in the abi4 vtc2 double mutant, as was the sugar-insensitive phenotype of the abi4 mutant. Octadecanoid derivative-responsive AP2/ERF-domain transcription factor 47 (ORA47) and AP3 (an ABI5 binding factor) transcripts were enhanced in vtc2 but repressed in abi4 vtc2, suggesting that ABI4 and ascorbate modulate growth and defense gene expression through jasmonate signaling. We conclude that low ascorbate triggers ABA-and jasmonate-dependent signaling pathways that together regulate growth through ABI4. Moreover, cellular redox homeostasis exerts a strong influence on sugar-dependent growth regulation.

The rice transcription factor OsWRKY47 is a positive regulator of the response to water deficit stress

“…Similar phenotypes, i.e. increased biomass (Kerchev et al 2011), were seen in both abi4 and water stressed P SARK ::IPT rice plants.…”

Influence of plastids on light signalling and development

“…ABSCISIC ACID INSENSI-TIVE4 (ABI4) acts downstream of GUN1 and helps to downregulate the expression of Lhcb1.2 by binding CCAC, which overlaps the G box in the Lhcb1.2 promoter [18]. The plastid regulation of PhANGs appears to require additional transcription factors and promoter elements because ABI4 did not contribute to the plastid regulation of Lhcb1.1 or RbcS [3,58] and CCAC did not contribute to the plastid regulation of an Lhcb gene from Nicotiana plumbaginifolia when chloroplast biogenesis was blocked with a norflurazon treatment [46]. GOLDEN2-LIKE 1 (GLK1) and PHD-type transcription factor with transmembrane domains (PTM) also contribute to this signalling [3] (see electronic supplementary material, figure S1).…”

Mitochondrial Energy and Redox Signaling in Plants

“…Inhibition of respiration at the level of complex III, IV, or V leads to a strong decrease in total cellular ascorbate content in plants (25,138,248). The effects of ascorbate on gene expression are well documented in Arabidopsis (94,95,163). A strong overlap of transcriptome signatures was reported between mutants of ABI4, VTC1 and VTC2 (94).…”

“…The effects of ascorbate on gene expression are well documented in Arabidopsis (94,95,163). A strong overlap of transcriptome signatures was reported between mutants of ABI4, VTC1 and VTC2 (94). The abi4 mutant is deficient in a TF that regulates sugar sensitivity of plants as well as mitochondrial and plastidial RTG signaling (64), whereas the vtc mutants are deficient in total cellular ascorbate.…”