Influence of gallic and tannic acids on enzymatic activity and growth of Pectobacterium chrysanthemi (Dickeya chrysanthemi bv. chrysanthemi)

The effect of phenolic acids (gallic and tannic acids) on growth of Pectobacterium chrysanhemi, and its protease and pectate lyase activities was tested. The results obtained showed a significant inhibitingeffect of the tannic and gallic acids on the growth of this strain. The growth rate decreases in the presence of 400 g/ml for gallic acid and 100 ìg/ml fortannic acid. The enzymatic activity retardationwas observed with the two phenolic compounds as well but the rate of inhibition varied from one compound to another. The highest antimicrobial potentials and the highest effect on enzymatic activities were observed with the tannic acid at 200 g/ml, which inhibited 91% of the tested microorganisms, and 88% of pectate lyase activity

Protection against bacterial soft rot by olive extracts is related to general defence induction in potato tubers

International audienceControlling bacterial plant diseases remains a challenge, as direct chemical control is usually not possible. Obtaining new biocontrol methods, in particular efficient biomolecules able to boost defence reactions and limit infection or symptom development, is therefore of major importance. This study screened extracts from leaves of two Mediterranean plants rich in bioactive phenolic compounds, olive and carob, for their ability to reduce soft rot severity and to trigger phenylalanine ammonia-lyase (PAL) activity in potato tuber slices. Extracts from olive leaves significantly reduced disease severity caused by Pectobacterium atrosepticum or Pectobacterium carotovorum, whereas carob leaf extracts significantly increased it. Olive extracts and its main phenolic components, oleuropein and hydroxytyrosol, also significantly increased PAL activity 7.5 h after application. None of the extracts or purified molecules reduced bacterial growth in vitro. Furthermore, the effect of these extracts varied according to potato cultivars. These data therefore open new ways for the biological control of soft rot bacteria, but stress the importance of understanding the causes of response difference in different potato varieties in order to obtain optimal efficacy

Antiangiogenic activity of neutral lipids, glycolipids, and phospholipids fractions of Pinus halepensis Mill. seeds

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