Dramatic changes in leaf development of the native Capsicum chinense from the Seychelles at temperatures below 24°C

Abstract

When a pepper cultivar (Capsicum chinense cv. Seychelles-2, Sy-2) native to the Seychelles was grown in Japan, all seedlings showed seasonal developmental abnormalities such as development of abnormally shaped leaves. Other pepper cultivars grew well in all seasons while the growth of cv. Sy-2 was stunted. In this study, we first examined the effects of various changes in temperature and photoperiod on the cv. Sy-2 phenotype. The results showed that temperatures lower than 24 degrees C led to the formation of abnormal leaves. Second, morphological and anatomical analyses of cotyledons and true leaves developed at 28 and 20 degrees C were conducted. The narrower and thicker cotyledons developed at 20 degrees C had fewer palisade cells in the leaf-length direction, and more cells in the leaf-thickness direction. True leaves developed at 20 degrees C were irregularly shaped, thicker and had smaller leaf area. In addition, true leaves developed at 20 degrees C had fewer palisade cells in the leaf-length and leaf-width directions and had more cells in the leaf-thickness direction. Furthermore, abnormal periclinal cell divisions in the mesophyll and/or epidermal cell layers were observed during leaf blade development at 20 degrees C. These results suggest that the observed changes in cell proliferation and abnormal periclinal cell divisions were related, at least in part, to abnormal leaf development of cv. Sy-2 at temperatures below 24 degrees C.