Genome-Wide Identification and Characterization of Chinese Cabbage S1fa Transcription Factors and Their Roles in Response to Salt Stress

Abstract

The S1fa transcription factor is part of a small family involved in plant growth and development and abiotic stress tolerance. However, the roles of the S1fa genes in abiotic stress tolerance in Chinese cabbage are still unclear. In this study, four S1fa genes in the Chinese cabbage genome were identified and characterized for abiotic stress tolerance. Tissue-specific expression analysis suggested that three of these four S1fa genes were expressed in all tissues of Chinese cabbage, while Bra006994 was only expressed in the silique. Under Hg and Cd stresses, the S1fa genes were significantly expressed but were downregulated under NaCl stresses. The Bra034084 and Bra029784 overexpressing yeast cells exhibited high sensitivity to NaCl stresses, which led to slower growth compared with the wild type yeast cells (EV) under 1 M NaCl stress. In addition, the growth curve of the Bra034084 and Bra029784 overexpressing cells shows that the optical density was reduced significantly under salt stresses. The activities of the antioxidant enzymes, SOD, POD and CAT, were decreased, and the MDA, H2O2 and O2− contents were increased under salt stresses. The expression levels of cell wall biosynthesis genes Ccw14p, Cha1p, Cwp2p, Sed1p, Rlm1p, Rom2p, Mkk1p, Hsp12p, Mkk2p, Sdp1p and YLR194c were significantly enhanced, while Bck1p, and Ptc1p were downregulated under salt stresses. These results suggest that the Bra034084 and Bra029784 genes regulate cell wall biosynthesis and the defense regulatory system under salt stresses. These findings provide a fundamental basis for the further investigation of crop genetic modification to improve crop production and abiotic stress tolerance in Chinese cabbage.

BrCYP71A15 Negatively Regulates Hg Stress Tolerance by Modulating Cell Wall Biosynthesis in Yeast

“…Thus, the Hg content might be increased in yeast cells, and the expression of cell wall biosynthesis genes might be activated. These findings are in line with previous studies, which reported that salt stress reduces the antioxidant enzymatic activities, enhances the ROS and MDA contents in S1fa cells and regulates the transcript level of genes involved in cell wall integrity [ 4 ]. In summary, it can be concluded that the BrCYP71A15 gene exhibits high sensitivity to Hg stress and increases Hg accumulation, which may play a key role in cell wall biosynthesis under Hg stress.…”

“…Protein Kinase C (PKC1) is regulated by BCK1p, MKK1p, SLT2p and ROM2p, which plays a fundamental role in cell wall biosynthesis, maintenance and cell integrity [ 23 , 31 ]. These findings are supported by a previous study, which reported that S1Fa OE cells regulate cell wall biosynthesis genes under salt stress in yeast [ 4 ]. Hence, it can be concluded that the BrCYP71A15 gene interacts with cell wall biosynthesis genes, and thus, Hg sensitivity is enhanced, and the accumulation of the Hg content is increased in yeast cells.…”

“…Chinese cabbage belongs to the Cruciferae family that originated in China [ 1 ], which has become one of the essential economic vegetable crops and is widely cultivated around the globe [ 2 , 3 ]. Over the past two decades, heavy metals have been considered a severe environmental threat to all living organisms, such as plants, animals and humans [ 4 ]. Global population has shown an intensive increment due to industrialization, during which excessive amounts of heavy metal pollutions such as mercury (Hg), cadmium (Cd), chromium (Cr), aluminum (Al), arsenic (As) and lead (Pb) have been produced [ 5 , 6 ].…”

“…Among these heavy metals, Hg is highly toxic even under low concentrations [ 6 ]. In plants, there are no specific channels to absorb and transport Hg from the root to the shoot [ 4 , 7 ]. The excessive accumulation of Hg causes physiological and biochemical disorders and decreases plant productivity [ 8 , 9 , 10 ].…”

“…The overproduction of ROS can influence the activities of essential enzymes such as GSH, SOD, POD, CAT, APX and GR [ 12 ]. The GR enzyme is highly sensitive to Hg stress and significantly reduced in alfalfa roots [ 4 , 11 , 13 , 14 ]. Hg stress damages root activities, interrupts water and nutrient absorption and reduces uptake capacity from the root to the shoot [ 11 ].…”