Interactive physiological potential of Peyronellaea curtisii (=Phoma narcissi) strains for enzymatic attack and defence capabilities against phytoalexins

Abstract

Phytopathogenic fungi use a variety of strategies to infect hosts and have a diverse sensitivity to the natural defence mechanisms of the host plant, e.g. synthesis of phytoalexins. Many important pathogens of crops belong to the problematic genus Phoma, including species recently reallocated to Peyronellaea. The work presents: (1) molecular identification of five pathogenic strains of Peyronellaea (syn. Phoma) based on two loci, actin (ACT) and β-tubulin (TUB), and morphological observations; (2) differentiation of these strains based on their enzymatic activity; and (3) their effect on biosynthesis of phytoalexin in Hippeastrum scales. Phylogenetic analysis showed a close relationship between our strains and Peyronellaea curtisii (syn. Phoma narcissi) species. This was also supported by morphoanatomical analysis although its results were less conclusive. Some phenotypic traits of the strains overlapped with characteristics of other Phoma s.l. species, allowing for misidentification based on morphology alone. Tested cellulolytic, pectolytic and amylolytic activities were strain specific. A high level of amylase activity was positively correlated with cellulase activity but negatively correlated with pectolytic activity. Moreover, some strains suppressed phytoalexin production in Hippeastrum scales and were resistant to various concentrations of phytoalexin added to the culture medium. Based on these results, we suggest that pathogenicity in P. curtisii strains is complex and that it may be associated with their interactive physiological potential for enzymatic attack and defence capabilities against phytoalexin.

Impact of jasmonates, salicylic acid, and fungal elicitor on the health of <i>Hippeastrum hybridum</i> bulbs achieved by <i>in vitro</i> procedure

“…e accumulation of phytoalexins has been reported to be related to the resistance of plants to pathogens. Such a group of secondary metabolites is present in Hippeastrum × hybridum and has been shown to have anti-fungal activity (Hrynkiewicz et al, 2016;Saniewska et al, 2005). In the present research, the ability of plants obtained by in vitro techniques and grown in such conditions to synthesize the proper amount of phytoalexin was analyzed.…”

“…), which was obtained from the National Institute of Horticultural Research in Skierniewice, Poland. Biotic elicitors and elicitation medium were prepared according to the method described by Hrynkiewicz et al (2016) with some modifications. e strain was first cultivated on solid medium (Potato Dextrose Agar) in Petri dishes at 26 °C ± 2 for 7 days of incubation.…”

“…2.5. Phytoalexin isolation from Hippeastrum hybridum microcuttings e elicited plants (bulbs) obtained from the in vitro culture were cut into small pieces (4 × 4 mm) and kept on Petri dishes at 20-22 °C in continuous light (70 μmol • m −2 • s −1 cool white Polam fluorescent tubes) at high humidity (Hrynkiewicz et al, 2016). e microcuttings cultivated on medium without any elicitors constituted the control.…”

“…e frozen tissues (100 mg) were crushed in liquid nitrogen using a mortar and pestle and extracted with 10 ml of 90% (v/v) methanol by shaking at 200 rpm for 10 min. e macerates were centrifuged for 20 min at 10,000 × g. e liquid fraction was collected and a UV absorption spectrum was obtained on the Shimadzu spectrophotometer (𝜆 = 495 nm) (Hrynkiewicz et al, 2016;Saniewska et al, 2005;Wilmowicz et al, 2014).…”

“…Following contact with the pathogen or mechanical damage, Hippeastrum cells produce phytoalexin, which is a mixture composed of an orange-colored chalcone (3,2′4′-trihydroxy-4methoxychalcone) and 3 flavans (7,4′-dihydroxy-8-methylflavan, 7,3′-dihydroxy-4′-methoxyflavan, and 7-hydroxy-3′-4′-methylenedioxyflavan) (Wink & Lehmann, 1996). When plants have enough time and are able to produce phytoalexin in sufficient quantities, they become more resistant to subsequent infections (Hrynkiewicz et al, 2016).…”