A tuber mustard AP2/ERF transcription factor gene, BjABR1, functioning in abscisic acid and abiotic stress responses, and evolutionary trajectory of the ABR1 homologous genes in Brassica species

Abstract

The AP2/ERF superfamily of transcription factors is one of the largest transcription factor families in plants and plays an important role in plant development processes and stress responses. In this study, BjABR1, an AP2/ERF superfamily gene, from tuber mustard (Brassica juncea var. tumida Tsen et Lee), sharing high amino acid sequence similarity with the AtABR1 (Arabidopsis thaliana AP2-like abscisic acid repressor 1) gene, were performed functional research, and the ABR1 homologous genes in Brassica species were identified and performed phylogenetic analysis. The promoter sequence of BjABR1 contained many phytohormone- and stress-related cis-elements; ABA (abscisic acid) and abiotic stresses can induce BjABR1 expression in tuber mustard; overexpression of BjABR1 in Arabidopsis can alleviate plant sensitivity to ABA and salt and osmotic stresses, and the alleviation may be due to changes in stress/ABA-induced gene expression. These results indicated that BjABR1 functions in ABA and abiotic stress responses. By BLAST searches against the genome database of five Brassica species (three diploids, B. rapa, B. nigra, and B. oleracea, and two allotetraploid, B. juncea and B. napus) using the protein sequence of AtABR1, 3, 3, 3, 6, and 5 ABR1 homologous genes in B. nigra, B. rapa, B. oleracea, B. juncea, and B. napus were identified, respectively, and they shared high sequence similarity. By sequence analysis, annotation mistakes of the protein-coding regions of two ABR1 homologous genes, GSBRNA2T00134741001 and BjuB007684, were found and corrected. Then, the evolution analysis of these ABR1 homologous genes showed that the ancestor of the three diploid species had three ABR1 homologous genes and each diploid inherited all the three genes from their ancestor; then, allotetraploid B. juncea inherited all the six genes from B. rapa and B. nigra with no gene lost, while allotetraploid B. napus inherited all the three genes from B. oleracea and two genes from B. rapa with one gene lost, indicating that ABR1 homologous genes possessed greater hereditary conservation in Brassica species. The ABR1 homologous genes between B. rapa and B. oleracea shared much higher sequence similarity compared to that of B. nigra in diploid species, indicating that ABR1 homologous genes in B. nigra had experienced more rapid evolution, and B. rapa and B. oleracea may share closer relationship compared to B. nigra. Moreover, the spatial and temporal expression analysis of six ABR1 homologous genes of tuber mustard showed that they possessed different expression models. These results imply that ABR1 homologous genes are important to Brassica plants, and they may possess similar function in ABA and abiotic stress responses but play a role in different tissues and growing stages of plant. This study will provide the foundation to the functional research of ABR1 homologous genes in the Brassica species and help to reveal and understand the evolution mechanisms of Brassica species.

An Overview of Hazardous Impacts of Soil Salinity in Crops, Tolerance Mechanisms, and Amelioration through Selenium Supplementation

“…A variety of adaptive mechanisms at the molecular level are involved in overcoming the harmful effects of salinity-induced oxidative stress. Some of the most important are the up and downregulation of gene transcripts [29,95,96], changes of chemical composition and the rigidness of plant's cell wall [97]. It was reported that the expression of antioxidant defense genes is stimulated in Zea mays L. shoots [98], while Rodríguez-Kessler found that two genes, Zmodc and Zmspds2A, are responsible for salinity tolerance in maize roots through the accumulation of polyamine and spermidine [99].…”

Genome-wide identification and expression analysis of AP2/ERF transcription factors in sugarcane (Saccharum spontaneum L.)

“…The AP2/EREBP (APETALA2/ethylene response element-binding protein) superfamily comprises a large class of transcription factors in plants. Multiple studies have demonstrated that AP2/ERF transcription factors in plants are essential for stresses responses, and their expression is regulated by plant hormones [5,6]. In response to stresses in plants, AP2/ERF transcription factors' expression is regulated to coordinate growth under stresses [7].…”

Genome-wide analysis of AP2/ERF Transcription Factors in sugarcane Saccharum spontaneum L. Reveals Functional Divergence During Drought, Salt Stress and Plant Hormones Treatment

“…The AP2/EREBP (APETALA2/ethylene response elementbinding protein) superfamily comprises a large class of transcription factors in plants. Multiple studies have demonstrated that AP2/ERF transcription factors in plants are important for stress responses, and their expression is regulated by plant hormones [5][6][7]. In response to stress in plants, expression of AP2/ERF transcription factors is regulated to coordinate growth under stress conditions [8].…”