ABSTRACT
In plantae, basic leucine zipper (bZIP) transcription factors (TFs) are widespread and regulate a variety of biological processes under abiotic stress. However, it has not been extensively studied in Rosaceae, and the functional effects of bZIP on Eriobotrya japonica under salt stress are still unknown. Therefore, in this study, the bZIP TF family of 12 species of Rosaceae was analyzed by bioinformatics method, and the expression profile and quantitative real-time polymerase chain reaction of E. japonica under salt stress were analyzed. The results showed that a total of 869 bZIP TFs were identified in 12 species of Rosaceae and divided into nine subfamilies. Differences in promoter cis-elements between subfamilies vary depending on their role. Species belonging to the same subfamily have a similar number of chromosomes and the number of genes contained on each chromosome. Gene duplication analysis has found segmental duplication to be a prime force in the evolution of Rosaceae species. In addition, nine EjbZIPs were significantly different, including seven up-regulated and two down-regulated in E. japonica under salt stress. Especially, EjbZIP13 was involved in the expression of SA-responsive proteins by binding to the NPR1 gene. EjbZIP27, EjbZIP30, and EjbZIP38 were highly expressed in E. japonica under salt stress, thus improving the salt tolerance capacity of the plants. These results can provide a theoretical basis for exploring the characteristics and functions of the bZIP TF family in more species and breeding salt-tolerant E. japonica varieties. It also provides a reference for resolving the response mechanism of bZIP TF in 12 Rosaceae species under salt stress.
ABSTRACT
BACKGROUND: Plant-specific TIFY proteins are widely found in terrestrial plants and play important roles in plant adversity responses. Although the genome of loquat at the chromosome level has been published, studies on the TIFY family in loquat are lacking. Therefore, the EjTIFY gene family was bioinformatically analyzed by constructing a phylogenetic tree, chromosomal localization, gene structure, and adversity expression profiling in this study. RESULTS: Twenty-six EjTIFY genes were identified and categorized into four subfamilies (ZML, JAZ, PPD, and TIFY) based on their structural domains. Twenty-four EjTIFY genes were irregularly distributed on 11 of the 17 chromosomes, and the remaining two genes were distributed in fragments. We identified 15 covariate TIFY gene pairs in the loquat genome, 13 of which were involved in large-scale interchromosomal segmental duplication events, and two of which were involved in tandem duplication events. Many abiotic stress cis-elements were widely present in the promoter region. Analysis of the Ka/Ks ratio showed that the paralogous homologs of the EjTIFY family were mainly subjected to purifying selection. Analysis of the RNA-seq data revealed that a total of five differentially expressed genes (DEGs) were expressed in the shoots under gibberellin treatment, whereas only one gene was significantly differentially expressed in the leaves; under both low-temperature and high-temperature stresses, there were significantly differentially expressed genes, and the EjJAZ15 gene was significantly upregulated under both low- and high-temperature stress. RNA-seq and qRT-PCR expression analysis under salt stress conditions revealed that EjJAZ2, EjJAZ4, and EjJAZ9 responded to salt stress in loquat plants, which promoted resistance to salt stress through the JA pathway. The response model of the TIFY genes in the jasmonic acid pathway under salt stress in loquat was systematically summarized. CONCLUSIONS: These results provide a theoretical basis for exploring the characteristics and functions of additional EjTIFY genes in the future. This study also provides a theoretical basis for further research on breeding for salt stress resistance in loquat. RT-qPCR analysis revealed that the expression of one of the three EjTIFY genes increased and the expression of two decreased under salt stress conditions, suggesting that EjTIFY exhibited different expression patterns under salt stress conditions.
