Phenylpropanoid enzymes, phenolic polymers and metabolites as chemical defenses to infection of Pratylenchus coffeae in roots of resistant and susceptible bananas (Musa spp.).

Activity differences of the first (phenylalanine ammonia lyase, PAL) and the last (cinnamyl alcohol dehydrogenase, CAD) enzymes of phenylpropanoid pathway in the roots of resistant (Yangambi Km5 and Anaikomban) and susceptible (Nendran and Robusta) banana cultivars caused by root lesion nematode, Pratylenchus coffeae, were investigated. Also, the accumulation of phenolics and deposition of lignin polymers in cell walls in relation to resistance of the banana cultivars to the nematode were analyzed. Compared to the susceptible cultivars, the resistant cultivars had constitutively significantly higher PAL activity and total soluble and cell wall-bound phenolics than in susceptible cultivars. The resistant cultivars responded strongly to the infection of the nematode by induction of several-time higher PAL and CAD enzymes activities, soluble and wall-bound phenolics and enrichment of lignin polymers in cell wall and these biochemical parameters reached maximum at 7th day postinoculation. In addition, profiles of phenolic acid metabolites in roots of Yangambi Km5 and Nendran were analyzed by HPLC to ascertain the underlying biochemical mechanism of bananas resistance to the nematode. Identification and quantification of soluble and cell wall-bound phenolic acids showed six metabolites and only quantitative, no qualitative, differences occurred between the resistant and susceptible cvs. and between constitutive and induced contents. A very prominent increase of p-coumaric, ferulic and sinapic acids, which are precursors of monolignols of lignin, in resistant cv. was found. These constitutive and induced biochemical alterations are definitely the chemical defenses of resistant cvs. to the nematode infection.

Density and speed of sound of sodium nitroprusside with aqueous alcohols

Studies on apparent molar volumes for the solutions of sodium nitroprusside in aqueous solutions of methanol, ethanol and propanol in the temperature range 298.15 to 313K at 5K intervals have been determined from the density measurements of the solutions. Speed of sound of solutions of sodium nitroprusside in aqueous solutions of alcohols has also been experimentally determined at 304.15K. Molar insentropic compressibilities and apparent molar isentropic compressibilities have been calculated from the speed of sound data. These results have been used to calculate the following partial molar quantities: V[phi], E[0][phi], K[0][s][phi] Various acoustic parameters and salvation number have been evaluated for sodium nitroprusside in different aqueous solutions of alcohols. The results are discussed in the light of solute-solvent and solute-solute interactions