Genome-wide sequencing identifies a thermal-tolerance related synonymous mutation in the mussel, Mytilisepta virgata

Abstract

The roles of synonymous mutations for adapting to stressful thermal environments are of fundamental biological and ecological interests but poorly understood. To study whether synonymous mutations influence thermal adaptation at specific microhabitats, a genome-wide genotype-phenotype association analysis is carried out in the black mussels Mytilisepta virgata. A synonymous mutation of Ubiquitin-specific Peptidase 15 (MvUSP15) is significantly associated with the physiological upper thermal limit. The individuals carrying GG genotype (the G-type) at the mutant locus possess significantly lower heat tolerance compared to the individuals carrying GA and AA genotypes (the A-type). When heated to sublethal temperature, the G-type exhibit higher inter-individual variations in MvUSP15 expression, especially for the mussels on the sun-exposed microhabitats. Taken together, a synonymous mutation in MvUSP15 can affect the gene expression profile and interact with microhabitat heterogeneity to influence thermal resistance. This integrative study sheds light on the ecological importance of adaptive synonymous mutations as an underappreciated genetic buffer against heat stress and emphasizes the importance of integrative studies at a microhabitat scale for evaluating and predicting the impacts of climate change.

Allele Sails: launching traits and fates into wild populations with DNA sequence modifiers

“…However, small variations such as point mutations or small indels at one or a modest number of loci can have a large effect. As examples, point mutations have been found that contribute to plant disease resistance 3 , animal heat tolerance 1,2 , and honeybee sensitivity to Varroa mites 4,5 . As another point of reference, as of 2019, half of the pathogenic variants in the human ClinVar database were point-mutations, and almost 90% of clinically relevant insertions and deletions were less than 30bp 54 .…”

“…These possibilities are suggested by the growing number of contexts in which one or a modest number of alleles of large effect can produce significant phenotypic benefits for a population. Examples include a single locus that can confer heat resistance in mussels 1 and cattle 2 , fungi resistance in certain plants 3 , or varroa mite resistance in bees 4,5 . There are also collections of loci that have been suggested to contribute to coral resistance to heat 6,7 , bird resistance to malaria 1,8 , or frog resistance to chytrid fungi 9 .…”

“…Examples include a single locus that can confer heat resistance in mussels 1 and cattle 2 , fungi resistance in certain plants 3 , or varroa mite resistance in bees 4,5 . There are also collections of loci that have been suggested to contribute to coral resistance to heat 6,7 , bird resistance to malaria 1,8 , or frog resistance to chytrid fungi 9 . Allele modifications can also be used to reduce harm, for example by limiting the ability of insects to vector disease 10,11 , or reducing the toxicity (poison production) of an invasive species such as cane toads.…”

“…Examples include a single locus that can confer heat resistance in mussels 1 and cattle 2 , fungi resistance in certain plants 3 , or varroa mite resistance in bees 4,5 . There are also collections of loci that have been suggested to contribute to coral resistance to heat 6,7 , bird resistance to malaria 1,8 , or frog resistance to chytrid fungi 9 .…”