Fulvic acid-induced disease resistance to Botrytis cinerea in table grapes may be mediated by regulating phenylpropanoid metabolism.

Gray mold caused by Botrytis cinerea is a major postharvest disease of table grapes that leads to enormous economic losses during storage and transportation. The objective of this study was to evaluate the effectiveness of fulvic acid on controlling gray mold of table grapes and explore its mechanism of action. The results showed that fulvic acid application significantly reduced downy blight severity in table grapes without exhibiting any antifungal activity in vitro. Fulvic acid induced phenylpropanoid metabolism, as evidenced by accumulation of phenolic compounds and flavonoids, higher activities of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL), up-regulation of genes related to phenylpropanoid biosynthesis (PAL, C4H, 4CL, STS, ROMT and CHS). Our results suggested that fulvic acid induces resistance to B. cinerea mainly through the activation of phenylpropanoid pathway and can be used as a new activator of plant defense responses to control postharvest gray mold in table grapes.

Acaricidal activity of DHEMH, derived from patchouli oil, against house dust mite, Dermatophagoides farinae.

This study characterized the acaricidal activity of constituents of patchouli oil extracted from (Pogostemon cablin (Blanco) BENTH) against the house dust mite, Dermatophagoides farinae. A new compound, 2-(1,3-dihydroxy-but-2-enylidene)-6-methyl-3-oxo-heptanoic acid (DHEMH), was isolated from patchouli oil and characterized by (1)H-NMR, (13)C-NMR, LC-MS and elemental analysis (EA). This active component was identified as the hydrolysate of pogostone. Fifteen other constituents found in patchouli oil were also identified by GC-MS, including patchouli alcohol and pogostone. LD(50) studies carried out over 24 h using contact toxicity tests identified DHEMH as the most toxic compound to D. farinae (2.04 µg/cm(2)), followed by patchouli oil (6.11 µg/cm(2)), benzyl benzoate (BP) (9.31 µg/cm(2)) and dibutyl phthalate (DBP) (58.52 µg/cm(2)). In vapor phase toxicity tests, all of these compounds were more effective in closed than open containers, indicating that the most efficient mode of delivery for these compounds is the vapor phase. These results indicate that DHEMH and patchouli oil merit further study as potential agents for the control of D. farinae.

[Identification of herba rabdosiae serrae from different plant resources by RAPD method].

OBJECTIVE: To identify the different plant resources of Herba Rabdosiae Serrae by using Random Amplified Polymorphic DNA ( RAPD ) Analysis. METHODS: The mini spin columns were used to extract the genomic DNA from five different plants of Herba Rabdosiae Serrae. With the DNA extracted from these plants as template,the 85 oligo nucleic acids (10 bp)as random primers,the polymer chain reaction (PCR) was done and the results were analysed by electro-pharoses. RESULTS: 12 primers were selected with polymorphism and 7 of them showed good polymorphism in RAPD map. CONCLUSION: RAPD method can be used to identify the plant resources of Herba Rabdosiae Serrae.