Influence of the green microalga Chlorella sorokiniana on seed germination in Arabidopsis thaliana

Recent studies in algae have revealed that they produce auxins-like compounds, which can affect land plants. Auxins play a crucial role in the growth and development of higher plants and are also used as herbicides or germination inhibitors. The aim of this work was to study the effects of a fresh water microalga on the germination and developing of Arabidopsis thaliana. Axenic liquid cultures of Chlorella sorokiniana were grown and used to prepare different types of solid agar-based media on which Arabidopsis was sowed. Germination was completely inhibited on the medium containing cells subjected to a treatment of mechanical lysis and on the medium with intact cells. GC-MS analysis confirmed the presence of free indole-3-acetic acid (IAA) in both liquid growing medium and cells. These results indicated that these microalgae produce free IAA at sufficient concentration to affect the seedlings development acting as herbicide.