Heterologous expression of EsABA1 enhances salt tolerance with increased accumulation of endogenous ABA in transgenic tobacco

Abstract

Salt stress can trigger several physiological responses in plants such as increased accumulation of ABA and antioxidant enzyme activities, which have been closely associated with the tolerance of plants to salt stress. In the present study a novel zeaxanthin epoxidase gene, designated EsABA1, was isolated from Eutrema salsugineum. EsABA1 contained a full-length open reading frame (ORF) of 2001 bp, encoding 666 amino acids. Transcription of EsABA1 rapidly accumulated after exposure to various abiotic stresses, suggesting that the EsABA1 gene was involved in multiple stress responses and tolerance. To further investigate the roles of EsABA1 under salt-stress conditions, transgenic tobacco lines that ectopically overexpressed EsABA1 were obtained. These transgenic lines exhibited more tolerance to salt stress than wild-type (WT) plants, and overexpression of EsABA1 increased the contents of ABA and proline as compared to WT plants under salt-stress conditions. Moreover, the expression levels of stress responsive genes and activities of antioxidant enzymes were much higher in the EsABA1-overexpressing lines than in WT plants. Therefore, our findings indicated that the elevated expression of EsABA1 enhanced the tolerance of transgenic tobacco plants to high salinity stress.

A homolog of Class IV HD-Zip transcription factors, EsHdzip1, confers drought resistance in tobacco via enhanced the capacity of water conserving and absorbing

“…High level of ABA accumulation is positively associated with the ability of plant tolerance to abiotic stress (Jiang and Zhang 2001;Yu et al 2008;Lu et al 2013;Sun et al 2014). Some recent studies have reported that overexpression of key genes involved in the ABA biosynthesis can significantly increase resistance to various abiotic stresses with enhanced activities of antioxidant enzymes and the expression levels of stressrelated genes (Lu et al 2013;Sun et al 2014). In our experiments, the expression of some stress-related gene including NtP5CS, NtERD10C, and NtLEA5 was visibly higher in the transgenic lines than WT plants after drought stress treatments.…”

“…For in vivo localization of two major types of reactive oxygen species (ROS) including H 2 O 2 and O 2 -, the H 2 O 2 and O 2 -in leaves from untreated and drought-stressed plants was examined as described by Sun et al (2014). Furthermore, the H 2 O 2 content was determined as described by Liu and Pang (2010) and the O 2 -content was analyzed using the method described by Mukherjee and Choudhuri (1983).…”

Rhizobacterial Strain Bacillus megaterium BOFC15 Induces Cellular Polyamine Changes that Improve Plant Growth and Drought Resistance

“…In vivo localization of ROS (O 2 − and H 2 O 2 ) in leaves from the control and inoculated plants was detected according to the method reported by Sun et al [ 53 ]. Moreover, the content of O 2 − and H 2 O 2 was quantified as recently by Liu and Pang [ 54 ].…”

Overexpression of EsMcsu1 from the halophytic plant Eutrema salsugineum promotes abscisic acid biosynthesis and increases drought resistance in alfalfa (Medicago sativa L.)

“…The expression levels of key genes that encode ABA biosynthetic enzymes are increased by various abiotic stressors, such as drought, cold, and high salinity (Barrero et al, 2006;Park et al, 2008;Sun et al, 2014;Xian et al, 2014). ABA biosynthetic pathways have been clearly identified in plants, and mainly involve the following three steps (Seo and Koshiba, 2002): 1) zeaxanthin epoxidase (ZEP) catalyzes the conversion of zeaxanthin to all-trans-violaxanthin, and through a series of structural modifications the violaxanthin is converted to 9-cis-epoxycarotenoid; 2) 9-cis-epoxycarotenoid dioxygenase (NCED) catalyzes the cleavage of 9-cis-violaxanthin and 9-cis-neoxanthin to generate xanthoxin, which is then converted to abscisic aldehyde (AA) by shortchain dehydrogenase/reductase; 3) AA is oxidized to ABA by AA oxidase (AAO), and molybdenum cofactor (MoCo) sulfurase (MCSU) catalyzes the production of the sulfurylated form of MoCo, which is required for AAO activity.…”

“…The overexpression of ABA biosynthetic genes, such as ZEP, NCED, and AAO, promotes ABA biosynthesis and increases drought resistance in many plant species, such as Arabidopsis, tobacco, and tomato (Yue et al, 2012;Sun et al, 2014;Xian et al, 2014). Therefore, screening key genes involved in ABA biosynthesis increases abiotic stress tolerance in crop plants.…”