Deciphering the population structure and genetic basis of growth traits from whole-genome resequencing of the leopard coral grouper(Plectropomus leopardus)

The leopard coral grouper(Plectropomus leopardus)is a species of significant economic importance.Although artificial cultivation of P.leopardus has thrived in recent decades,the advancement of selective breeding has been hindered by the lack of comprehensive population genomic data.In this study,we identified over 8.73 million single nucleotide polymorphisms(SNPs)through whole-genome resequencing of 326 individuals spanning six distinct groups.Furthermore,we categorized 226 individuals with high-coverage sequencing depth(≥14×)into eight clusters based on their genetic profiles and phylogenetic relationships.Notably,four of these clusters exhibited pronounced genetic differentiation compared with the other populations.To identify potentially advantageous loci for P.leopardus,we examined genomic regions exhibiting selective sweeps by analyzing the nucleotide diversity(θπ)and fixation index(FST)in these four clusters.Using these high-coverage resequencing data,we successfully constructed the first haplotype reference panel specific to P.leopardus.This achievement holds promise for enabling high-quality,cost-effectiveimputationmethods.Additionally,we combined low-coverage sequencing data with imputation techniques for a genome-wide association study,aiming to identify candidate SNP loci and genes associated with growth traits.A significant concentration of these genes was observed on chromosome 17,which is primarily involved in skeletal muscle and embryonic development and cell proliferation.Notably,our detailed investigation of growth-related SNPs across the eight clusters revealed that cluster 5 harbored the most promising candidate SNPs,showing potential for genetic selective breeding efforts.These findings provide a robust toolkit and valuable insights into the management of germplasm resources and genome-driven breeding initiatives targeting P.leopardus.

SMXL5 attenuates strigolactone signaling in Arabidopsis thaliana by inhibiting SMXL7 degradation

Hormone-activated proteolysis is a recurring theme of plant hormone signaling mechanisms.In strigolactone signaling,the enzyme receptor DWARF14(D14)and an F-box protein,MORE AXILLARY GROWTH2(MAX2),mark SUPPRESSOR OF MAX21-LIKE(SMXL)family proteins SMXL6,SMXL7,and SMXL8 for rapid degradation.Removal of these transcriptional corepressors initiates downstream growth responses.The homologous proteins SMXL3,SMXL4,and SMXL5,however,are resistant to MAX2-mediated degradation.We discovered that the smxl4 smxl5 mutant has enhanced responses to strigolactone.SMXL5 attenuates strigolactone signaling by interfering with AtD14-SMXL7 interactions.SMXL5 interacts with AtD14 and SMXL7,providing two possible ways to inhibit SMXL7 degradation.SMXL5 function is partially dependent on an ethylene-responsive-element binding-factor-associated amphiphilic repression(EAR)motif,which typically mediates interactions with the TOPLESS family of transcriptional corepressors.However,we found that loss of the EAR motif reduces SMXL5-SMXL7 interactions and the attenuation of strigolactone signaling by SMXL5.We hypothesize that integration of SMXL5 into heteromeric SMXL complexes reduces the susceptibility of SMXL6/7/8 proteins to strigolactone-activated degradation and that the EAR motif promotes the formation or stability of these complexes.This mechanism may provide a way to spatially or temporally fine-tune strigolactone signaling through the regulation of SMXL5 expression or translation.