Hormone released by the microalgae Neochlorisaquatica and alkalinization influence growth of terrestrial and floating aquatic plants

• Published in: Plant physiology and biochemistry 2023-04, Vol.197, p.107635-107635, Article 107635
• Main Authors: Gil, M. Florencia, Azzara, Nayla, Fassolari, Marisol, Berón, Corina M., Battaglia, Marina E.
• Format: Article
• Language: English
• Subjects: adult development; algae culture; Alkalinization; aquatic plants; Arabidopsis; Arabidopsis thaliana; Auxins; biological control agents; Biological Control Agents - pharmacology; carbon metabolism; carbonates; Culex quinquefasciatus; Hormones - pharmacology; Lemna; Lemna sp; Microalgae; midgut; mortality; Neochloris; plant growth; Plants; toxicity
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2023.03.012

The microalgae Neochloris aquatica were previously evaluated as a potential biological control agent and source of bioactive compounds against immature stages of Culex quinquefasciatus. Larvae reared on microalgae suspension showed mortality or drastic effects with morphological alterations and damage in the midgut. N. aquatica have nutritional and toxic effects, resulting in delayed life cycle and incomplete adult development. Given the possibility of its use as a biological control agent, in this work we evaluate the effect of microalgae on other organisms of the environment, such as plants. Arabidopsis thaliana, a terrestrial plant, and Lemna sp., a floating aquatic plant, were selected as examples. Interaction assays and compound evaluations showed that the microalgae release auxins causing root inhibition, smaller epidermal cells and hairy root development. In Lemna sp., a slight decrease in growth rate was observed, with no deleterious effects on the fronds. On the other hand, we detected a detrimental effect on plants when interactions were performed in a closed environment, in a medium containing soluble carbonate, in which microalgae culture rapidly modifies the pH. The experiments showed that alkalinization of the medium inhibits plant growth, causing bleaching of leaves or fronds. This negative effect in plants was not observed when plants and microalgae were cultured in carbonate-free media. In conclusion, the results showed that N. aquatica can modify plant growth without being harmful, but the rapid alkalinization produced by carbon metabolism of microalgae under CO2-limiting conditions, could regulate the number of plants. •Microalgae release compounds that modulate the growth and development of organisms in their habitat.•Neochloris aquatica are microalgae with larvicidal activity on mosquitoes and release auxins into the environment.•Interaction with Arabidopsis thaliana caused a change in root architecture generating hairy roots.•Interaction with aquatic plant, such as Lemna sp., slightly affected frond growth.•Microalgae cutivated with soluble carbonate, in closed environment, cause severe damage to plants.