Light-harvesting chlorophyll a/b-binding proteins, positively involved in abscisic acid signalling, require a transcription repressor, WRKY40, to balance their function

Abstract

The light-harvesting chlorophyll a/b-binding (LHCB) proteins are the apoproteins of the light-harvesting complex of photosystem II. In the present study, we observed that downregulation of any of the six LHCB genes resulted in abscisic acid (ABA)-insensitive phenotypes in seed germination and post-germination growth, demonstrating that LHCB proteins are positively involved in these developmental processes in response to ABA. ABA was required for full expression of different LHCB members and physiologically high levels of ABA enhanced LHCB expression. The LHCB members were shown to be targets of an ABA-responsive WRKY-domain transcription factor, WRKY40, which represses LHCB expression to balance the positive function of the LHCBs in ABA signalling. These findings revealed that ABA is an inducer that fine-tunes LHCB expression at least partly through repressing the WRKY40 transcription repressor in stressful conditions in co-operation with light, which allows plants to adapt to environmental challenges.

Genome-Wide Identification and Characterization of Light Harvesting Chlorophyll a/b Binding Protein Genes in Barley (Hordeum vulgare L.)

“…There were also several studies showed that members of LHCB family play an important role in plant adaptation to environmental stresses [10,27,28]. Previous studies also showed that some LHCB members of Arabidopsis were positively involved in ABA dependent processes, such as stomatal movement, response to drought [10] and seed germination [11]. This study found that there were one to five ABREs in the promoter regions of 16 HvLHCs which indicated that expression of them may be responsive to ABA.…”

“…Except for their roles as antenna proteins, some members of this gene family have also been proved to be involved in development of plants. For instance, six LHCB members of Arabidopsis (Lhcb1.1, Lhcb 2.2, Lhcb 3, Lhcb 4.4, Lhcb 5 and Lhcb 6) were positively involved in ABA signaling in stomatal movement and response to drought [10], and also in seed germination and postgermination growth in response to ABA [11]. Down-regulation of Lhcb1 by microRNA in Arabidopsis slowed down the growth as compared to wide type, and leaves of these transgenic lines were slightly smaller and paler [9].…”

Light-specific transcriptional regulation of the accumulation of carotenoids and phenolic compounds in rice leaves

“…ABA is normally required in high level for the full expression of different LHCB proteins and then ABA-responsive WRKYdomain TF which represses LHCB expression acts to balance the positive function of the LHCBs. 15 Therefore, in blue light treatment, ABA could act as an inducer to fine-tune LHCB expression in rice leaves and high level of carotenoids supports in activating photosynthesis and photoprotection. Higher biosynthesis of GA in both blue and red light treatment agrees with our identification of a number of GA response elements associated with MYB TF which are involved in the regulation of the biosynthesis of a-and b-carotene, and lutein.…”

Identification of Winter-Responsive Proteins in Bread Wheat Using Proteomics Analysis and Virus-Induced Gene Silencing (VIGS)

“…The light-harvesting chlorophyll a/b-binding (LHCB) proteins are the apoproteins of the light-harvesting complex of photosystem II (56). Chlorophyll a/b-binding-like protein genes were up-regulated in higher plants that were exposed to Ϫ12°C-freeze stress (57); after a 3-day exposure to Ϫ5°C-simulated spring freeze stress, chlorophyll a/b-binding-like protein genes were up-regulated in wheat (41), implying that they play a protective role in cold-stress tolerance.…”