Sex and developmental stage of carob flowers affects composition of volatiles

Abstract

SummaryThe aim of this work was to evaluate the volatiles composition in the scent emitted in vivo by the three types of carob tree (Ceratonia siliqua L.) flowers, during the different developmental stages. Additionally, an overview of some morphological aspects of carob flowers was also done. Carob trees may be male, female, hermaphrodite or exhibit polygamous inflorescences. The androecium of male flowers consists of a group of 5–7 stamens, inserted peripherically around the receptacle. The gynoecium of female flowers is apocarpous. Hermaphrodite flowers are a combination of male and female types. During the flower development six stages were identified. The volatile compounds of flowers were analysed by headspace solid-phase microextraction followed by capillary gas chromatography and mass spectrometry detection (HS-SPME-CGC/MSD). More than 25 compounds were identified, and flowers in stages III and IV showed higher abundances. In male and hermaphrodite flowers the total volatile compounds were more abundant in stage III, and in female flowers in stage IV. Linalool and trans linalool oxide were the dominant volatiles and there were remarkable differences in those compounds between different types of flowers and during the developmental stages. The results observed were discussed in terms of their possible implication on pollination efficiency.