Genetic characterization of a locus responsible for low pungency using EMS-induced mutants in Capsicum annuum L.
Theor Appl Genet
; 137(5): 101, 2024 Apr 12.
Article
in En
| MEDLINE
| ID: mdl-38607449
ABSTRACT
KEY MESSAGE The pepper mutants ('221-2-1a' and '1559-1-2h') with very low pungency were genetically characterized. The Pun4 locus, responsible for the reduced pungency of the mutant fruits, was localized to a 208 Mb region on chromosome 6. DEMF06G16460, encoding 3-ketoacyl-CoA synthase, was proposed as a strong candidate gene based on the genetic analyses of bulked segregants, DEG, and expression analyses. Capsaicinoids are unique alkaloids present in pepper (Capsicum spp.), synthesized through the condensation of by-products from the phenylpropanoid and branched-chain fatty acid pathways, and accumulating in the placenta. In this study, we characterized two allelic ethyl methanesulfonate-induced mutant lines with extremely low pungency ('221-2-1a' and '1559-1-2h'). These mutants, derived from the pungent Korean landrace 'Yuwolcho,' exhibited lower capsaicinoid content than Yuwolcho but still contained a small amount of capsaicinoid with functional capsaicinoid biosynthetic genes. Genetic crosses between the mutants and Yuwolcho or pungent lines indicated that a single recessive mutation was responsible for the low-pungency phenotype of mutant 221-2-1a; we named the causal locus Pungency 4 (Pun4). To identify Pun4, we combined genome-wide polymorphism analysis and transcriptome analysis with bulked-segregant analysis. We narrowed down the location of Pun4 to a 208-Mb region on chromosome 6 containing five candidate genes, of which DEMF06G16460, encoding a 3-ketoacyl-CoA synthase associated with branched-chain fatty acid biosynthesis, is the most likely candidate for Pun4. The expression of capsaicinoid biosynthetic genes in placental tissues in Yuwolcho and the mutant was consistent with the branched-chain fatty acid pathway playing a pivotal role in the lower pungency observed in the mutant. We also obtained a list of differentially expressed genes in placental tissues between the mutant and Yuwolcho, from which we selected candidate genes using gene co-expression analysis. In summary, we characterized the capsaicinoid biosynthesis-related locus Pun4 through integrated of genetic, genomic, and transcriptome analyses. These findings will contribute to our understanding of capsaicinoid biosynthesis in pepper.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Capsicum
Limits:
Female
/
Humans
/
Pregnancy
Language:
En
Journal:
Theor Appl Genet
Year:
2024
Document type:
Article