Phenotypic plasticity is essential for responding rapidly to environmental variations, which is important to increase the fitness of organism under global climate change. However, the genetic and evolutionary mechanism underlying the plasticity in the marine organism remains poorly understood.
Recently, the research team led by Prof. LI Li from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) confirmed that the cis- and trans-variations shape the diverged pattern of phenotypic plasticity in stearoyl-CoA desaturase (Scd) gene and its metabolic product oleic acid (C18:1) in two congeneric oysters. The divergent pattern regulates the fluidity of cell membranes for temperature adaptation.
The study was published in Molecular Biology and Evolution on Jan. 20.
Common garden culture and indoor temperature stress experiments showed a diverged temperature responding pattern in Scd gene expression and downstream metabolic product C18:1. Crassostrea gigas (C. gigas, relative low temperature adapted specie) showed higher constitutive expression and content, and Crassostrea angulata (C. angulata, relative high temperature adapted specie) showed higher upregulated magnitude. This is trade-offs between constitutive expression and plastic expression, which may be mediated by genetic assimilation, one of the important evolutionary modes of plasticity.
Genetic screening and functional experiments demonstrated that 16 single nucleotide polymorphisms (SNPs), located in the promoter regions (~2k) of Scd, showed different frequencies and formed a strong linkage disequilibrium block (LD Block). Among these SNPs, one interacts with the positive transcriptional factor Y Box Factor, and the different allele of the causative SNP can create/destroy the cis-regulatory motif, which mediates higher constitutive expression of Scd in C. gigas. And the different expression pattern (down-regulated in C. gigas and up-regulated in C. angulata) in positive trans-factor Sterol-regulatory element binding proteins (Srebp) under low temperature stress may mediate the higher upregulated magnitude of Scd in C. angulata.
"As a case study, this study reveals that cis- and trans-variations shape the divergence of phenotypic plasticity, which provides new insights into the evolution of plasticity in marine organism and its important role in the formation of adaptive traits and the prediction of the adaptation potential of marine organisms in facing future global climate change," said WANG Chaogang, first author of the study.
"Based on this study, our team is carrying out genetic improvement and designed breeding in C. gigas and C. angulata," added Prof. LI.
This work was supported by the National Key R & D Program of China, National Natural Science Foundation of China, Strategic Priority Research Program of the Chinese Academy of Sciences and Key Research and Development Program of Shandong, etc.
Schematic representation of Scd plastic expression pattern in C. gigas and C. angulata shaped by cis- and trans-variations.
Chaogang Wang, Ao Li, Rihao Cong, Haigang Qi, Wei Wang, Guofan Zhang, Li Li. (2023). Cis- and trans-variations of Stearoyl-CoA Desaturase Provide New Insights into the Mechanisms of Diverged Pattern of Phenotypic Plasticity for Temperature Adaptation in Two Congeneric Oyster Species. Molecular Biology and Evolution.
(Text by WANG Chaogang & LI Li)
Institute of Oceanology
(Editor: ZHANG Yiyi)