Isolation and purification of a 316 Da preformed compound from strawberry (Fragaria ananassa) leaves active against plant pathogens

Abstract

An antibiotic called fragarin showing activities against bacterial and fungal plant pathogens was isolated and purified by FPLC chromatography from the soluble fraction of strawberry leaves. The molecular weight value determined by mass spectrometry is 316 Da. Fragarin remains fully active after protease treatment or alkaline hydrolysis at 100³C for 20 min. Biological and chemical analyses suggest that fragarin may be a new type of an antimicrobial preformed compound^phytoanti-cipin^and would constitute a primary non-specific barrier of strawberry defense.z 1999 Federation of European Biochemical Societies.

Induction of a defense response in strawberry mediated by an avirulent strain of Colletotrichum

“…In no case was the inhibition of M11 observed (results not shown). On the plant, in contrast, the germination of M11 conidia were completely arrested in the presence of F7 (Figure 5d), but according to the result shown in Figure 5b, the effect should not be attributed to the presence of preformed plant compounds such as phytoanticipins present at inhibitory concentrations (Filippone et al, 1999(Filippone et al, , 2001. Hence, taking into account that: (i) intact F7 does not inhibit the growth of M11 in vitro, (ii) F7 conidial extracts and strawberry leaf extract do not affect the growth of M11 in vitro, (iii) M11 can actively grow on the plant in the absence of F7 but is completely arrested by F7 on the plant, we may conclude that whatever inhibits M11 on the plant could be an inhibitory factor produced by F7 or by the plant only after (or during) their interaction.…”

“…A commercial fungicide Euparen (EU) and strawberry methanolic leaf extract (LE) were used as controls. The latter was included to test whether any preformed compound present in strawberry leaves was responsible for M11 inhibition (Filippone et al, 1999(Filippone et al, , 2001. In Figure 5b we show that M11 grew to confluence displaying no inhibition halo, regardless of the concentration of conidial extracts and supernatant of culture medium.…”

Pathogen-Induced Accumulation of an Ellagitannin Elicits Plant Defense Response

“…Secondary metabolites can serve to attract animals for pollination and seed dispersal, as protection against UV, and as key components of active and potent defense mechanisms that help plants to protect themselves against pathogens (viruses, bacteria, and fungi) and herbivores (arthropods and vertebrates) (Wink 2003;Wu and Baldwin 2009). Although many secondary metabolites involved in plant defense are constitutive (Bednarek and Osbourn 2009;Filippone et al 1999), some are specifically induced upon challenge by a hostile organism (Van Etten et al 1994). Secondary metabolites may act directly by exerting toxic effects on the aggressor (Dixon 2001) or indirectly as elicitors of plant defense (Dangl and Jones 2001).…”

Ellagitannin HeT obtained from strawberry leaves is oxidized by bacterial membranes and inhibits the respiratory chain

“…We have previously reported the isolation from strawberry leaves of a 936 Da ellagitannin (1‐ O ‐galloyl‐2,3;4,6‐bis‐hexahydroxydiphenoyl‐β‐ d ‐glucopyranose) called HeT . It was shown that HeT elicits from plants a strong defense response against anthracnose disease caused by the virulent isolate of the fungal pathogen Colletotrichum acutatum , and also exhibits a direct antimicrobial activity against other pathogens, as reported earlier for another 316 Da compound also obtained from strawberry leaves called fragarin . These authors showed that fragarin affected the respiration of the bacterium Clavibacer michiganensis , showing a bacteriolytic effect, and these effects were due to the alteration of the cellular membrane integrity .…”