Expression and polymorphism of farnesoic acid O-methyltransferase (FAMeT) and association between its SNPs and reproduction-related parameters of the giant tiger shrimp Penaeus monodon

• Two full-length cDNAs of Penaeus monodon farnesoic acid O-methyltransferase (FAMeT) were identified.
• PmFAMeT was differentially expressed during ovarian development of P. monodon.
• Eyestalk ablation and 5-HT injection promoted PmFAMeT expression.
• Association between its SNPs and ovarian weight of domesticated shrimp was found.
• The expression level of PmFAMeT in shrimp with T/C and T/T genotypes (position c.487+g.10) was different.

Two full-length cDNAs of farnesoic acid O-methyltransferase (FAMeT) in the giant tiger shrimp (Penaeus monodon) were identified. They were 1296 and 1311 bp in length containing ORFs of 828 (PmFAMeT-s) and 843 (PmFAMeT-l) bp deducing to polypeptides of 275 and 280 amino acids. PmFAMeT mRNA was down-regulated at stages II and III ovaries and up-regulated in stage IV (mature) ovaries in wild intact broodstock (P < 0.05). In eyestalk-ablated broodstock, its expression level in stages III and IV ovaries was significantly greater than that in stages I and II ovaries (P < 0.05). Exogenous serotonin injection (5-HT; 50 μg/g body weight) significantly promoted its expression level in ovaries of 18-month-old shrimp approximately 50 folds at 1 h post injection (hpi, P < 0.05). PmFAMeT mRNA was localized in previtellogenic oocytes but was not observed in oogonia and more mature stages of oocytes. Western blot analysis revealed the positively reactive band of 32 kDa along with a smaller band of approximately 29 kDa in stages I–IV ovaries of wild intact broodstock. The latter was not observed in premature ovaries of juveniles. In addition, single nucleotide polymorphisms (SNPs) in PmFAMeT of 14-month-old P. monodon (N = 65) were indirectly examined by single-stranded conformational polymorphism (SSCP) analysis. Results revealed that domesticated shrimp having different SSCP genotypes of PmFAMeT possessed a different average ovarian weight (P < 0.05). Six SNPs were found in cloned PmFAMeT gene segments of 14-month-old shrimp (N = 65). Two SNPs (positions c.487+g.10 and c.487+g.174+c.38) were significantly associated with the average ovarian weight of examined shrimp (P < 0.05). In addition, the relative expression level of ovarian PmFAMeT mRNA in shrimp with T/Cc.487+g10 and T/Tc.487+g10 was also significantly different (P < 0.001).