Acyl-homoserine Lactone from Saccharum × officinarum with Stereochemistry-Dependent Growth Regulatory Activity

Acyl-homoserine lactones (AHLs) are a class of compounds produced by Gram-negative bacteria that are used in a process of chemical communication called quorum sensing. Much is known about how bacteria use these chemical compounds to control the expression of important factors; however, there have been few reports about the presence and effects of AHLs in plants. In this study, the phytochemical study of leaves and culms of sugar cane (Saccharum × officinarum) led to the identification of N-(3-oxo-octanoyl)homoserine lactone. Since the absolute configuration of the natural product could not be determined, both R and S enantiomers of N-(3-oxo-octanoyl)homoserine lactone were synthesized and tested in sugar cane culms. The enantiomers caused changes in the mass and length of buds and roots when used at micromolar concentrations. Using the sugar cane RB96-6928 variety, the S enantiomer increased sprouting of roots more effectively than the R enantiomer. Furthermore, scanning electron microscopy showed that both the R and S enantiomers led to more stretched root cells compared with the control.