Metabolic Profiling Horizontal Resistance in Potato Leaves (cvs. Caesar and AC Novachip) Against Phytophthora Infestans

Abstract

Abstract:Metabolic profiles were developed for potato leaves, cvs. Caesar and AC Novachip, inoculated with water (CW and AW) or Phytophthora infestans (CP and AP), using gas chromatography/mass spectrometry (GC/MS). The level of horizontal resistance was higher for cv. Caesar than for AC Novachip with an area under the lesion expansion curve (AULEC) of 334 and 857, lesion area of 86 and 224 mm 2 , and sporulation of 4.4 × 10 3 and 13.7 × 10 3 sporangia lesion -1 , respectively. A total of 51 metabolites were detected consistently in all the four replicates of at least one treatment. Of the 51 relatively consistent metabolites, 33 were unique to a treatment and 18 were common to two or more treatments. A total of 7 and 29 PR-metabolites were identified, respectively, in Caesar and AC Novachip cultivars. Most of the phenolic compounds were associated with the AP. The metabolite heptadecanoic acid, 16-methy was detected only in the CP. In response to the P. infestans attack, the two cultivars appear to follow two different pathways. The susceptible cv. AC Novachip appears to follow the Shikimic acid-phenylpropanoid pathway as we have detected many phenolic metabolites and benzoic acids, the latter is a precursor of the signal molecule salicylic acid (SA), known to trigger phenolic compounds. On the other hand, the resistant cv. Caesar appears to follow mevalonic acid-methylerythritol pathway as we have detected heptadecanoic acid, a probable derivative of linolenic acid that is a precursor of a signal molecule jasmonic acid (JA), known to trigger terpenes. The factor analysis using principal components discriminated all the four treatments and the factor loading indicated which compound loaded significantly to a treatment. The possible function of these compounds in plant defense against biotic stress is discussed.

Metabolic profiles of peanut (Arachis hypogaea L.) in response to Puccinia arachidis fungal infection

“…In our study, 9, 12-octadecadienoic acid (precursor of JA) content was increased in resistant genotype during Puccinia arachidis infection. A similar pattern was also observed in potato plants during Phytophthora infestans infection [ 48 ]. During the pathogen attack, linoleic acid content increased in avocado plants, which shows its antifungal activity [ 49 ].…”

“…The 2,3,4-trihydroxybutyric acid was also considered as a defense-related metabolite in peanut, which showed a significant increase at IS-3 compared to the control stage. The up-regulation of this organic acid was also found in potato leaves during inoculation with Phytophthora infestans [ 48 ]. Flavonoids are frequently detected as biomarkers of fungi infected plants.…”