Abstract
The acyl-homoserine lactones (AHL) are compounds used in intercellular chemical signaling processes by Gram-negative bacteria in a phenomenon known as quorum-sensing. This process makes the microorganisms able to sense and respond to stimuli of individuals of the same species, or even cause physiological changes in the surrounding bacterial populations. In recent years, there is a growing interest in the effect that these compounds might have on higher organisms, such as inter-kingdoms communication mechanisms or physiological and morphological changes in host. In this regard, the study of the effects of these metabolites in plants has gained particular attention. Recently, it was shown that N-(3-oxo-octanoyl)-HL is present in the extract obtained from the leaves and stalks of sugarcane cultivated in Brazil, and that this compound can stimulate the growth of roots and shoots of the plant at low concentrations. Interestingly, it was found that both enantiomers (R) and (S) can accelerate plant growth. Thus, it is reported herein the chemical syntheses of N-acyl-HL derivatives with structural variations in the acyl side chain length and presence of carbonyl groups, and their growth-promoting activity evaluation on sugarcane meristems. It was found that all derivatives were able to stimulate plant growth, being N-decanoyl-HL the most active compound. Compounds (R)-N-decanoyl-HL and its (S) enantiomer caused significant increase of growth of roots and shoots in meristems of sugarcane compared to the control. However, the test highlighted the (S) enantiomer, which caused an increase in the average weight of dry roots and root length of 90.1% and 92.1%, respectively. A surprising increase in average mass of dry buds and buds length of 134.2% and 390.0% were observed when the stems of sugarcane were treated with this compound. Thus the (S) enantiomer has proved to be more active than the (R) one. It is believed that these compounds may represent a new frontier for development of plant growth active compounds with application in commercial agriculture.
