LAUSR

Abstract Liquid extracts of several seaweeds possess great potential as biostimulants for use in agricultural plants. Numerous studies have provided evidence of improved growth and yield parameters in crop plants treated with seaweed extracts. Still, there is a shortage of information available on the mechanisms of action of these extracts on plant growth processes. Enhanced flowering is one of the improved parameters often reported in seaweed extract treated plants for which the mechanisms are yet to be elucidated. In the current study, foliar application of brown seaweed extracts from A. nodosum and Sargassum sp. has significantly increased the flower bud, flower, and fruit number in treated tomato plants. In an effort to understand the molecular basis for enhanced flowering, a transcriptional analysis was carried out to determine the effect of treating tomato plants with two brown seaweed extracts on the expression levels of important flowering genes. Total RNAs were extracted from the apical shoots, floral buds, and flowers at weekly intervals between two and eight weeks. Quantitative Polymerase Chain reaction was used to determine the gene expression levels of six major flowering genes, including Single Flower Truss (SFT), Self-Pruning (SP), Jointless (J), Anantha (AN), Falsiflora (FA) and Constans-1 (CO). The results of the study revealed increased levels of expression of all six flowering genes when treated with either A. nodosum or Sargassum sp. alkaline extracts. Specific enhancements of gene expressions varied between the two treatments over the time intervals. The present study provides evidence of the potential role of seaweed extracts on an enhanced flowering phenomenon observed in tomato which helps justify the sustainable use of seaweed extracts in horticultural crops.