Overexpression of HbMBF1a, encoding multiprotein bridging factor 1 from the halophyte Hordeum brevisubulatum, confers salinity tolerance and ABA insensitivity to transgenic Arabidopsis thaliana

Abstract

Key message HbMBF1a was isolated and characterized in H. brevisubulatum, and overexpressed HbMBF1a could enhance the salt tolerance and ABA insensitivity in Arabidopsis thaliana. The transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions. Abstract Salinity is an abiotic stress that considerably affects plant growth, yield, and distribution. Hordeum brevisubulatum is a halophyte that evolved to become highly tolerant to salinity. Multiprotein bridging factor 1 (MBF1) is a transcriptional coactivator and an important regulator of stress tolerance. In this study, we isolated and characterized HbMBF1a based on the transcriptome data of H. brevisubulatum grown under saline conditions. We overexpressed HbMBF1a in Arabidopsis thaliana and compared the phenotypes of the transgenic lines and the wild-type in response to stresses. The results indicated that HbMBF1a expression was induced by salt and ABA treatments during the middle and late stages. The overexpression of HbMBF1a in A. thaliana resulted in enhanced salt tolerance and ABA insensitivity. More specifically, the enhanced salt tolerance manifested as the increased seed germination and seedling growth and development. Similarly, under ABA treatments, the cotyledon greening rate and seedling root length were higher in the HbMBF1a-overexpressing lines, suggesting the transgenic plants were better adapted to high exogenous ABA levels. Furthermore, the transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions. Thus, HbMBF1a is a positive regulator of salt and ABA responses, and the corresponding gene may be useful for producing transgenic plants that are salt tolerant and/or ABA insensitive, with few adverse effects. This study involved a comprehensive analysis of HbMBF1a. The results may provide the basis and insight for the application of MBF1 family genes for developing stress-tolerant crops. Keywords HbMBF1a • STEM (short time-series expression miner) • Hordeum brevisubulatum • Transgenic Arabidopsis thaliana • Salt and ABA treatments Electronic supplementary material The online version of this article (

Complete chloroplast genome of Hordeum brevisubulatum: Genome organization, synonymous codon usage, phylogenetic relationships, and comparative structure analysis

“…Until now, research on H . brevisubulatum has focused mainly on its biological characteristics, salt tolerance mechanisms, and disease resistance [ 1 , 7 , 8 ]. The lack of genetic information on H .…”

“…Molecular breeding is based on genetic information and has helped developing many new cultivars with high yield, quality, and resistance to stress. Until now, research on H. brevisubulatum has focused mainly on its biological characteristics, salt tolerance mechanisms, and disease resistance [1,7,8]. The lack of genetic information on H. brevisubulatum slows the pace of cultivation of different varieties.…”

Halophytic Hordeum brevisubulatum HbHAK1 Facilitates Potassium Retention and Contributes to Salt Tolerance

“…To survive under saline conditions for plants, maintaining continuous K + acquisition at high external Na + content is crucial for K + /Na + homeostasis. The halophytic H. brevisubulatum could grow well under heavy saline-alkali land and be used as a saline-tolerant grass for soil improvement in North China [ 26 , 32 ], implying that the H. brevisubulatum plant may evolve some distinctive strategies for K + acquisition improvement under saline conditions. The hypothesis was supported by the salt-treated root transcriptome data which showed abundant genes related to potassium ion transport were upregulated [ 26 ].…”

Heterologous Expression of a Soybean Gene RR34 Conferred Improved Drought Resistance of Transgenic Arabidopsis

“…For evaluation of root elongation, seeds of WT and transgenic lines were germinated on MS medium and allowed to grow for 4 days. After that, the seedlings were transferred to MS plates, supplemented with different concentrations of ABA (0, 0.3, and 0.5 µM) and let grow vertically for 8 days prior to the measurement of root length [102]. Ten biological replicates were used for each genotype for determining of root growth capacity under ABA treatment.…”