Antifungal activity of Pseudomonas chlororaphis Q16 against Sclerotinia sclerotiorum isolated from different medicinal plants

Abstract

Phytopathogenic fungi Sclerotinia sclerotiorum is very destructive pathogen of the stem of many medicinal plants. Because the use of pesticides is forbidden during production of medicinal plants, presence of S. sclerotiorum may produce serious loss. The use of PGP (Plant Growth Promoting) bacteria, for which have been demonstrated to show antifungal activity with varying degrees of antagonism, gives protection to medicinal plants. The antifungal activity of different fractions of P. chlororaphis Q16 culture was examined on 6 representative isolates of S. sclerotiorum from medicinal plants: nettle, cumin, marshmallow, valerian and two strains of Echinacea. The highest efficacy of mycelial growth inhibition showed heat stabile antifungal factor with growth inhibition range from 52.75% (marshmallow isolate) up to 83.36% (isolate from E. purpurea). The inhibition of mycelial growth was similar for all S. sclerotiorum isolates when 24h culture was performed and ranged from 60.28% (cumin isolates) to 76.47% (nettle isolates).

Fitopatogena gljiva Sclerotinia sclerotiorum je veoma destruktivni patogen stabla brojnih vrsta lekovitih biljaka. Kako u proizvodnji lekovitih biljaka nije dozvoljena upotreba pesticida, prisustvo ovog patogena prouzrokuje ozbiljne štete. Primena PGP (Plant Growth Promoting) bakterija, kao antagonista S. sclerotiorum, omogućuje zaštitu lekovitih biljaka. U ovim istraživanjima je ispitana aktivnost soja Pseudomonas chlororaphis Q16, pripadinka vrste koja spada među najefikasnije antagoniste S. sclerotiorum. Antifungalna aktivnost različitih frakcija kulture P. chlororaphis Q16 ispitivana je na 6 reprezentativnih izolata S. sclerotiorum poreklom sa različitih lekovitih biljaka: koprive, kima, belog sleza, odoljena i 2 vrste Echinacea. Najefikasnija je bila primena termostabilnih antifungalnih metabolita, frakcije koja je inhibirala porast micelije od 52,75% (izolata sa belog sleza) do 83,36% (izolata sa E. purpurea). Najujednačenija inhibicija porasta micelije ispoljena je primenom kultura starih 24h: od 60,28% (izolata sa kima) do 76,47% (izolata sa koprive).