LsBADH1 gene identified as the genetic basis of sweet fragrance in lettuce varieties

A preprint deposited on bioRxiv on 16 June 2026 presents genetic and functional evidence that LsBADH1, a gene encoding a betaine aldehyde dehydrogenase (BADH) enzyme, underlies the sweet fragrant trait in lettuce (Lactuca sativa L.) through its role in the biosynthesis of 2-acetyl-1-pyrroline (2AP).

2AP is the volatile compound responsible for the characteristic aroma of fragrant rice varieties, as well as fragrant cultivars of several other crops. The genetic basis of 2AP-derived fragrance in rice — the BADH2 gene — has been well characterised, but the equivalent mechanism in lettuce had not previously been confirmed. The authors conducted linkage analysis using an F2 mapping population derived from a cross between a fragrant lettuce cultivar ('Kukichisya') and a non-fragrant cultivar ('Rennet'), and identified LsBADH1 as the causative locus among candidate BADH orthologues.

The finding extends knowledge of convergent evolution in crop fragrance genetics and may be of interest to lettuce breeders seeking to introduce or characterise fragrance traits. It also adds to the broader picture of how BADH gene family members have been recruited independently for 2AP biosynthesis across diverse crop species. This preprint has not yet undergone formal peer review.