Analysis and Characterization of the GABA Transaminase and Succinate Semialdehyde Dehydrogenase Genes in the Microalga Isochrysis zhanjiangensis in Response to Abiotic Stresses

• Published in: Journal of Ocean University of China Vol. 23; no. 3; pp. 775 - 785
• Main Authors: Tian, Jiaojiao, Zhang, Lin, Lu, Xinyue, Ye, Lingzhi, Wu, Yuanyuan, Chen, Deshui, Cao, Jiayi, Jiang, Jiaxin, Xu, Jilin, Yan, Xiaojun
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01-06-2024; Springer Nature B.V
• Subjects: 4-Aminobutyrate transaminase; Algae; Aquatic microorganisms; Bioaccumulation; Biosynthesis; Degradation; Dehydrogenase; Dehydrogenases; Earth and Environmental Science; Earth Sciences; Environmental stress; Genes; Heat stress; Heat tolerance; Isochrysis; Meteorology; Microalgae; Nucleotide sequence; Oceanography; PCR; Phytoplankton; Polymerase chain reaction; Salinity; Salinity effects; Salinity tolerance; Sodium chloride; Survival; Temperature preferences; Transaminase; Transaminases; Transcription; Tricarboxylic acid cycle; Yeast; Yeasts; γ-Aminobutyric acid; GABA; heterologous expression; transcription; abiotic stress
• ISSN: 1672-5182; 1993-5021; 1672-5174
• DOI: 10.1007/s11802-024-5743-5

Gamma-aminobutyric acid (GABA), widely existing in different organisms, is rapidly accumulated in plants in response to environmental stresses. The main biosynthesis and degradation pathways of GABA constitute the GABA shunt, which is tied to the tricarboxylic acid (TCA) cycle. GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH) are two essential enzymes for the GABA degradation pathway. While there are abundant studies on GABA shunt in higher plants at the physiological and genetic levels, research on its role in microalgae remains limited. This study aimed at exploring the function of
GABA-T
and
SSADH
genes in
Isochrysis zhanjiangensis
, an important diet microalga, under different stresses. We cloned two
GABA-T
genes,
IzGABA-T1
and
IzGABA-T2
, and one
SSADH
gene
IzSSADH
from
Isochrysis zhanjiangensis
and conducted heterologous expression experiments. The results showed that the overexpression of
IzGABA-T1
or
IzGABA-T2
enhanced the survival rates of yeast transformants under heat or NaCl stress, while the overexpression of
IzSSADH
improved yeast tolerance to NaCl stress but had no obvious effect on heat stress. Additionally, the results of quantitative real-time polymerase chain reaction (qPCR) showed that
IzGABA-T1
transcription increased in the HT (salinity 25, 35°C) and LS (salinity 15, 25°C) groups. At 24 h, the
IzGABA-T2
transcriptions increased in the HT, LS, and HS (salinity 35, 25°C) groups, but their transcription levels decreased in all groups at 48 h.
IzSSADH
transcription increased in the LS group. These results suggest that
IzGABA-T1, IzGABA-T2
, and
IzSSADH
are associated with temperature and salinity stresses and possess a certain preference for different stresses.