Salicylic acid is involved in the regulation of starvation stress-induced flowering in Lemna paucicostata

The short-day plant, Lemna paucicostata (synonym Lemna aequinoctialis), was induced to flower when cultured in tap water without any additional nutrition under non-inductive long-day conditions. Flowering occurred in all three of the tested strains, and strain 6746 was the most sensitive to the starvation stress conditions. For each strain, the stress-induced flowering response was weaker than that induced by short-day treatment, and the stress-induced flowering of strain 6746 was completely inhibited by aminooxyacetic acid and l-2-aminooxy-3-phenylpropionic acid, which are inhibitors of phenylalanine ammonia-lyase. Significantly higher amounts of endogenous salicylic acid (SA) were detected in the fronds that flowered under the poor-nutrition conditions than in the vegetative fronds cultured under nutrition conditions, and exogenously applied SA promoted the flowering response. The results indicate that endogenous SA plays a role in the regulation of stress-induced flowering.