Organic fertilizers or natural-based biomolecules for plant growth and development are gaining much attention among farmers.In this context, seaweeds and seaweed extract have been extensively studied for their plant growth regulation effect.Alginate oligosaccharides are reported to be potent plant growth stimulant which enhances seed germination and seedling growth. They are involved in nitrogen metabolism and are effective against various stress responses.
Recently,researcher explained the mechanism of AOS on root growth of rice (Oryza sativa L) with emphasis on auxin metabolism. The expression of auxin-related genes such as OsYUCCA1, OsYUCCA5, OsIAA11, and OsPIN1 in rice tissues was screened with different AOS concentrations (10–80 mg/ml). They concluded that AOS accelerates the IAA biosynthesis through an increased level of OsIA11 and OsPIN1 genes, and it significantly minimizes the activity of IAA oxidase in rice roots and increases the calcium signaling.
Nitrogen metabolism plays a vital role in plant physiology as it is essential to synthesis amino acids, proteins and nucleic acids. Nitrogen metabolism is directly linked with Ca2+ ions, which induces the various enzymes involved in nitrogen metabolism . It was already reported that the calcium-alginate complex initiates the signal transduction pathways in plants, but the mechanism is not yet fully explored . This was further confirmed by Zhang et al. (2011), where calcium and alginate oligosaccharides in the nitrogen metabolism of Chinese cabbage were studied in the hydroponic culture. The increased amount of nitrate reductase, glutamine synthase, glutamate dehydrogenase, and endopeptidase was well correlated with increased total protein and total nitrogen and decreased nitrate content in shoots with AOS treated cabbage plants.
Similarly,researcher found that the exogenous application of AOS significantly induced Ca2+ ions, which regulates nitrogen metabolism in the flowering of Chinese cabbage. In another study, the role of alginate oligosaccharide in root development was evaluated . AOS at a 10–80mg/Lwas effective for inducing nitric oxide generation in wheat roots in a dose-dependent manner. These results revealed that Ca2+ signaling might be a downstream messenger of nitric oxide in AOS persuaded root formation facilitated by auxin.
Figure 1. Applications of alginate oligosaccharides.
Reference:Process and applications of alginate oligosaccharides with emphasis on health beneficial perspectives