Sargassum seaweed extract enhances Macrophomina phaseolina resistance in tomato by regulating phytohormones and antioxidative activity.

Seaweed extracts (SWE) possess great potential as bio-stimulants for improving agricultural yield. They also reduce the use of chemicals that have detrimental effects on the environment. The bactericidal, antiviral and fungicidal functional properties of SWE are due to the presence of biologically active components that stimulate plant stress signalling pathways and promote growth and productivity. In the present study, the efficacy of a brown algal, Sargassum tenerrimum extract (S-extract), towards managing Macrophomina phaseolina resistance in tomato was analysed. The application of S-extract (10%) alone and in combination with the fungus M. phaseolina significantly enhanced shoot and root length. Stress-inducible salicylic acid (SA) and abscisic acid (ABA) showed maximum accumulation with combination treatment (Macrophomina and S-extract) and Macrophomina treatment, respectively, during both vegetative and reproductive stages. The growth-related kinetin and indole-3-acetic acid (IAA) hormones showed maximum accumulation with Macrophomina during the vegetative stage and during reproductive stage; control plants had maximum accumulation. Superoxide radical (O2●-) showed significant differential regulation during both vegetative and reproductive stages, whereas H2O2 was significantly regulated only during the reproductive stage. Antioxidative enzymes (SOD, CAT, GR, APX and POX) showed maximum accumulation with the combination treatment during the vegetative stage. During the reproductive stage SOD, CAT, APX and POX showed maximum accumulation with S-extract treatment. The S-extract can serve as a bio-stimulant as it provides Macrophomina resistance in tomato by modulating phytohormones and antioxidative enzymes and improves yield. [ABSTRACT FROM AUTHOR]