Chromatographic Characterization and Phytotoxic Activity of Fusarium oxysporum f. sp. albedinis and Saprophytic Strain Toxins

Abstract

The bayoud disease, vascular fusariosis of date palm tree (Phoenix dactylifera L.)

A relationship between Bayoud disease severity and toxin susceptibility of date palm cultivars

“…To establish the relation between the pathogenicity and phytotoxicity of Foa isolates, it was essential to determine the composition of fraction FII and the effect of this phytotoxin fraction on different organs of plant (seeds and leaves) of susceptible and resistant date palm cultivars. However, the extraction procedure includes an organic precipitation of high molecular weight metabolites, essentially proteins and enzymes, indicating that the fraction FII is mainly composed of low to moderate molecular weight of organic components (El Fakhouri et al, 1996a,b) such as fusaric acid a common toxin of most Fusarium species as previously described (Amraoui et al, 2005).…”

“…However plants inoculated with Foa I12 showed no mortality until the third month of inoculation. This shows that the attack level expressed by the appearance of symptoms and virulence by the mortality rate among these 3 isolates may have several explanations, including the reduction of the production of toxic metabolites responsible for the appearance of symptoms as showed for saprophytic strains by Amraoui et al (2005) or the induction of defense mechanisms in date palm inoculated by hypoagressive Foa I12 isolate as polyphenoloxidase activities .…”

“…In the present study, a high effect of culture filtrate produced by the aggressive isolates of Foa L18 and Foa 133 was observed as hypoagressive Foa I12. This may be due to production of more potent toxic metabolites playing a key role on pathogenesis as fusaric and phenylacetic acids (Amraoui et al, 2005;Ait Kettout and Rahmania, 2010). However, the fact that the effect of culture fi ltrate of L18 at 100% is superior to the effect of FA at 50 μg/ml and the yield of this molecule is less than 50 μg/ml of CF as showed by Amraoui et al (2005) refl ects the presence of other toxic molecules acting in synergy with FA on detached leaves of date palm.…”

“…Rapid tests using Foa toxins on detached leafl ets, complete young plantlets and seedlings of date palm have been developed (Sedra et al, 1993;Sedra and Lazrek, 2011). Previous studies of Foa toxin extract showed that they produce similar symptoms (rolling and withering of leaves) in detached date palm leaves bioassays compared to pathogenicity tests conducted by pathogen inoculation of date palm plants (Sedra et al, 1998), also pathogenic and saprophytic strains of Fusarium oxysporum produce different biochemical profi les of toxins (Amraoui et al, 2005). The phytotoxin produced by aggressive Foa include fusaric acid (Amraoui et al, 2005) succinic, 3-phenyl lactic acids and phenylacetic acid (Amraoui et al, 2005;Ait Kettout and Rahmania, 2010).…”