Abstract
Abscisic acid (ABA) has been implicated in plant adaptation to various environmental stresses in addition to the regulation of seed dormancy and leaf senescence. ABI3 is a B3 domain-containing family protein and functions in the ABA signaling pathway during seed development. To date, the ABI3 orthologous have not been studied in Brassica napus. The aim of this study is to investigate the function of BnABI3 in plant development and stress response. Here, we identified an Arabidopsis line (gs1) from a population of mutagenized seeds and showed that GS1 is a new allele of AtABI3. When the Arabidopsis gs1 mutant was transformed with the BnABI3 gene, the transformed plants produced seeds that turned yellow and acquired desiccation tolerance. Moreover, BnABI3 regulates seed coat development and mucilage secretion by directly targeting the AtMUM1 and AtGATL5 genes. In addition, we showed that BnABI3 expression rescued gs1 freezing-induced green seed coloration by targeting AtSGR1/2 in transgenic Arabidopsis. BnABI3 is also involved in lateral root development and conferred a novel interaction between ABA and auxin signaling in roots. The potential role of ABI3 protein in endoplasmic reticulum homoeostasis was also tested. Altogether, our results indicated that BnABI3 mediates both plant development and the stress response.
Highlights
The Abscisic acid (ABA) hormone participates in seed lipid and storage protein synthesis, seed desiccation tolerance and dormancy promotion as well as the inhibition of transition from embryonic to germinative growth (Rohde et al, 2000b)
In addition to the ability to germinate on 2 M uniconazole, the gs1 mutant was segregated by the production of dark green shriveled seeds in the M3 generation, which could not be germinated after desiccation (Figure 1A)
We screened a new allele of the Arabidopsis ABSCISIC ACID INSENSITIVE3 (ABI3) gene, gs1, which allowed plants to germinate on 2 M uniconazole and caused them to produce green seeds
Summary
The ABA hormone participates in seed lipid and storage protein synthesis, seed desiccation tolerance and dormancy promotion as well as the inhibition of transition from embryonic to germinative growth (Rohde et al, 2000b). ABA signaling at these development stages is associated with the expression of several major regulatory genes involved in seed maturation. The ABI3 transcription factors have important roles in the control of ABA-responsive genes in seed, especially those genes important for dormancy inception, desiccation tolerance and reserve deposition (Giraudat et al, 1992; Nambara et al, 1995; Rohde et al, 2000a; Shiota and Kamada, 2000; Zhang et al, 2005; Khandelwal et al, 2010; Finkelstein, 2013; Nakashima and Yamaguchi-Shinozaki, 2013)
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