Variations in capsaicinoid contents in the chili pepper (Capsicum baccatum) and its non-pungent accessions

The chili pepper (Capsicum) is both an important spice and fresh vegetable worldwide. C. baccatum is a lesser known domesticated species that is native to the Andean region. Fruit traits such as color, shape, and pungency markedly vary in this species. C. baccatum has potential as a bioresource for future chili pepper breeding programs. Although extensive studies have been conducted on the pungency of C. annuum, that of C. baccatum has not been examined in as much detail. In the present study, capsaicinoid contents were analyzed in 36 C. baccatum accessions. Capsaicinoid contents ranged between 0 and 4,258 μg/gDW. Furthermore, a negative relationship was observed between capsaicinoid contents and fruit weights. Although the pungency of C. baccatum is regarded as low-mild, very few non-pungent accessions were detected ; only one non-pungent accession (‘Kaleidoscope’) was identified among the C. baccatum accessions examined. In order to validate the stability of non-pungency in the accession, capsaicinoid contents were determined at different harvest dates, along with other accessions with different pungencies. Although capsaicinoid contents in other C. baccatum accessions changed with the picking date, capsaicinoid was not detected in ‘Kaleidoscope’ at any date. The non-pungent accession reported here may be useful for future C. baccatum pepper breeding programs.

　トウガラシ（Capsicum 属）は世界的に重要な香辛料および野菜である．C. baccatum は南米原産のマイナーな栽培種であるが，果色，果形や辛味など果実形質に多様性が認められることから，トウガラシ遺伝資源として注目されている．トウガラシの辛味性についてはC. annuum 種において多くの研究が行われているが，C. baccatum 種においては十分研究されていない．
　本研究では，C. baccatum 36系統について辛味成分カプサイシノイドの含量を調査した．カプサイシノイド含量の幅は0 ～4,258 ㎍ /gDW であった．また果実重と辛味成分含量の間に負の相関が認められた．C. baccatum の辛味は低〜中程度であるが，非辛味系統はほとんど認められず，唯一1 系統（‘Kaleidoscope’）が非辛味であった．この非辛味の安定性を調査するために，辛味程度の異なる系統とともに異なる収穫時期におけるカプサイシノイド含量を調査した．
　他のC. baccatum 系統ではカプサイシノイド含量は収穫時期で変化したが，‘Kaleidoscope’ ではいずれの収穫時期でもカプサイシノイドは検出されなかった．本研究で見出された非辛味系統は将来のC. baccatum の育種において有用であろう．

原著論文 (Original paper)