Physiological and genetical studies on the pungency of Capsicum, IV. Secretory organs, receptacles and distribution of capsaicin in the Capsicum fruit_

Abstract

1. Histological and histochemical observationson capsaicin-secreting organs and receptacles, and measurements of capsaicin content in variou.s parts of the fruits were carried out with four strains of Capsiculee annuum L 2. Ripe fruits of Takanotsume×Large Bell F₁ were used as material for histological examination, because they contain a considerable quantity of capsaicin (O.28% of dry matter) and are large (Fig. 1). It was found that the receptacles are spherical or spheroid structures, about 0.3-1.0mm in diameter, with a thin cuticle layer on the surface 10cated along the interlocular septa. Their taste is rextremely pungent and it was confirmed by color lreaction with MARQUIS' reagent that they contained capsaicin. 3. The secretory organs consist of epidermal cells, which are slender, filled with cytoplasm and cell contents, and located just under the receptacles (Fig. 2). The development of a receptacle begins by splitting or separating of the cuticle layer from the secretory cells of a young fruit 10 days after flowering (Fig. 2) . 4. Ripe fruits of Takanotsume × Large Bell F₁ Fushimi-amanaga, and Ojishi were divided into three parts : pericap, seeds, and placenta with interlocular septa, or top, middle and base of the fruit. Capsaicin content of each part was measured (Tabs. 1-3 and Fig. 3). Placenta and interlocular septa showed much more capsaicin than the other parts of the fruit. It is considered that capsaicin in pericarp and seeds is due to the adherence of the rest of the receptacles after their destruction. 5. Capsaicin content in parthenocarpic fruits of autotetraploid Takanotsume was examined. It was almost the same as that of normal fruits without seeds (Tab. 4) .