An Analysis of Volatile Compounds and Study of Release Regularity in the Flower of Amorphophallus titanum in Four Periods

Abstract

Titan arum (Amorphophallus titanum) is a rare and endangered plant in the world. It has a huge flower and releases a repulsive odor like a corpse. On the evening of 23 July 2022 (Beijing time), a titan arum in the north garden of the China National Botanical Garden in Beijing bloomed. In order to determine the components and contents of volatile compounds released by the titan arum during its flowering, the dynamic headspace adsorption method was utilized to collect the odor of the titan arum flower on the evening of 23 July (S1), the morning of 24 July (S2), the afternoon of 24 July (S3) and the evening of 24 July (S4). The volatile compounds were analyzed by automatic thermal desorption–gas chromatography/mass spectrometry. Sixty-three volatile compounds were detected in the titan arum flower in four periods. The comparison of the total volatile compounds released in four periods was S2 > S3 > S1 > S4. The highest content of volatile compounds in the S1 period were sulfur compounds (dimethyl disulfide and dimethyl trisulfide), and the sulfur compounds were released in large amounts only in the S1 period. Dimethyl disulfide was the volatile substance with the highest content in the S1 period (20.00%). The total volatile compounds content of titan arum flower in the S2 period was the highest among the four periods. From the S2 period, the relative content of sulfur compounds decreased significantly until the S4 period. Compared with the S1 period, 1-butanol and butyl acrylate increased significantly and 1-butanol became the highest relative component of volatile compounds in the S2 period. After the S3 period, the total amount of volatile compounds began to decline and reached the lowest level in the S4 period. It is worth noting that the contents of two terpenes, α-pinene and γ-terpinene, rose from the S1 period until their height in the S3 period. From the S4 period, the contents of most volatile compounds decreased significantly. This study revealed the varieties and contents of volatile compounds in the titan arum flower at different flowering periods. The changing trend and physiological significance of dimethyl oligosulfide from the evening of flowering (S1) to the second day (S2–S4) were emphatically discussed, and this research also provides a reference for the study of the release of volatile compounds and the molecular biology of the flower fragrance of titan arum.