Variations in the Phenolic Contents of Cocoyam Clones in Correlation to Resistance to Pythium Myriotylum
Phenolic compounds from leaves and roots of infected and healthy cocoyam clones resistant (RO1075), tolerant (RO1043), and susceptible (RO1157) to Pythium myriotylum were quantified and tested for their in vitro fungitoxicity on the causal agent of the cocoyam root rot disease. All clones, infected or not, have phenolic compounds showing fungitoxic activity. The phenolic content of the tolerant and susceptible clones is less than that observed in the resistant one meanwhile in the resistant clone RO1075, a large increase in phenolic content is observed particularly in the roots during attack by pathogen.
Common Strategies to Control Pythium Disease
Pythium species are soil-borne pathogens which can cause serious economic loss worldwide and threatening agricultural production. Traditional management methods like chemical fungicides are effective against Pythium spp. But as people pay more attention to human health and environmental issues, alternative methods that are ecofriendly and harmless to health are urgently needed. Currently, various approaches had been made including using natural extract, regulating planting conditions, using plant growthpromoting rhizobacteria and screening disease tolerance plants. Hereby, we review the recent achievements, particularly chemical and physical methods, biocontrol and host plant defense which can be used to control Pythium disease.
Lignin-carbohydrate complex formed in isolated cell walls of callus
Abstract Cell walls of Pinus elliottii tissue cultures were isolated and incubated with coniferyl alcohol and H2O2. Lignin having physical and chemical properties similar to that prepared from wood was formed by the peroxidase attached to the walls. Fractions of the callus lignin isolated enzymatically or chemically contained bound carbohydrate. The lignin was also strongly bound to a protein containing hydroxyproline, probably extensin. This system may be analogous to the earliest stage of normal lignin formation in which monomers are transported from the protoplast into the primary wall and middle lamella, where peroxidase polymerizes monomers and catalyzes bonds to carbohydrate and protein.