AtbZIP62 Acts as a Transcription Repressor to Positively Regulate ABA Responses in Arabidopsis

The Role of Abscisic Acid (ABA) Machinery in Stress Response

Increasing global temperatures, in tandem with predicted increases in future frequencies of drought and flooding episodes, represent a threat to agricultural productivity [...].

AtAUEs, a Small Family of ABA Up-Regulated EAR Motif-Containing Proteins Regulate ABA Responses in Arabidopsis

The abscisic acid (ABA) signaling pathway is crucial for regulating downstream ABA-responsive genes, which influence plant responses to ABA and abiotic stresses. However, many ABA-responsive genes remain poorly characterized. This study reports on the identification and characterization of ABA up-regulated EAR motif-containing proteins (AtAUEs), a novel family of EAR motif-containing proteins in Arabidopsis thaliana. From a previous transcriptome dataset, AtAUEs were identified as a family of unknown-function ABA-response genes with only five members, and the up-regulation of AtAUEs by ABA was further confirmed by quantitative RT-PCR (qRT PCR). All AtAUEs contain at least one LxLxL EAR motif and can repress reporter gene expression in Arabidopsis protoplasts. We generated CRISPR/Cas9 gene-edited ataue1, ataue2 and ataue3 single, ataue1 ataue2 (ataue12) double, and ataue1 ataue2 ataue3 (ataue123) triple mutants, as well as transgenic plants overexpressing AtAUE1, and examined their ABA sensitivity. We found that the single and double mutants displayed wild-type responses to ABA treatment, while the ataue123 triple mutants showed increased sensitivity in seed germination and cotyledon greening assays but decreased sensitivity to ABA treatment in root elongation assays. Conversely, the 35S:AtAUE1 showed decreased sensitivity in seed germination and cotyledon greening assays but increased sensitivity to ABA treatment in root elongation assays. The qRT PCR results show that the expression level of ABI5 was increased in the ataue123 mutants and decreased in the 35S:AtAUE1 plants. These findings suggest that AtAUEs function redundantly to regulate ABA responses in Arabidopsis, likely by modulating the expression of key regulatory genes in ABA-signaling pathway.

Understanding AP2/ERF Transcription Factor Responses and Tolerance to Various Abiotic Stresses in Plants: A Comprehensive Review

Abiotic stress is an adverse environmental factor that severely affects plant growth and development, and plants have developed complex regulatory mechanisms to adapt to these unfavourable conditions through long-term evolution. In recent years, many transcription factor families of genes have been identified to regulate the ability of plants to respond to abiotic stresses. Among them, the AP2/ERF (APETALA2/ethylene responsive factor) family is a large class of plant-specific proteins that regulate plant response to abiotic stresses and can also play a role in regulating plant growth and development. This paper reviews the structural features and classification of AP2/ERF transcription factors that are involved in transcriptional regulation, reciprocal proteins, downstream genes, and hormone-dependent signalling and hormone-independent signalling pathways in response to abiotic stress. The AP2/ERF transcription factors can synergise with hormone signalling to form cross-regulatory networks in response to and tolerance of abiotic stresses. Many of the AP2/ERF transcription factors activate the expression of abiotic stress-responsive genes that are dependent or independent of abscisic acid and ethylene in response to abscisic acid and ethylene. In addition, the AP2/ERF transcription factors are involved in gibberellin, auxin, brassinosteroid, and cytokinin-mediated abiotic stress responses. The study of AP2/ERF transcription factors and interacting proteins, as well as the identification of their downstream target genes, can provide us with a more comprehensive understanding of the mechanism of plant action in response to abiotic stress, which can improve plants' ability to tolerate abiotic stress and provide a more theoretical basis for increasing plant yield under abiotic stress.

Genome-Wide Identification of GATA Family Genes in Phoebe bournei and Their Transcriptional Analysis under Abiotic Stresses

GATA transcription factors are crucial proteins in regulating transcription and are characterized by a type-IV zinc finger DNA-binding domain. They play a significant role in the growth and development of plants. While the GATA family gene has been identified in several plant species, it has not yet been reported in Phoebe bournei. In this study, 22 GATA family genes were identified from the P. bournei genome, and their physicochemical properties, chromosomal distribution, subcellular localization, phylogenetic tree, conserved motif, gene structure, cis-regulatory elements in promoters, and expression in plant tissues were analyzed. Phylogenetic analysis showed that the PbGATAs were clearly divided into four subfamilies. They are unequally distributed across 11 out of 12 chromosomes, except chromosome 9. Promoter cis-elements are mostly involved in environmental stress and hormonal regulation. Further studies showed that PbGATA11 was localized to chloroplasts and expressed in five tissues, including the root bark, root xylem, stem bark, stem xylem, and leaf, which means that PbGATA11 may have a potential role in the regulation of chlorophyll synthesis. Finally, the expression profiles of four representative genes, PbGATA5, PbGATA12, PbGATA16, and PbGATA22, under drought, salinity, and temperature stress, were detected by qRT-PCR. The results showed that PbGATA5, PbGATA22, and PbGATA16 were significantly expressed under drought stress. PbGATA12 and PbGATA22 were significantly expressed after 8 h of low-temperature stress at 10 °C. This study concludes that the growth and development of the PbGATA family gene in P. bournei in coping with adversity stress are crucial. This study provides new ideas for studying the evolution of GATAs, provides useful information for future functional analysis of PbGATA genes, and helps better understand the abiotic stress response of P. bournei.