Enhancement of natural disease resistance in potatoes by chemicals

Abstract

The mechanism involved in systemic acquired resistance (SAR) can be non-specifically induced in susceptible plants. In response to pathogens, plants' natural defence mechanisms include the production of lignin and phytoalexins and the induction of plant enzymes. The aim of this research was to study the induction of SAR mediated by the chemical activator DL-3-aminobutyric acid (BABA) and the fungicide fosetyl-aluminium in potato cultivars with different levels of resistance against Phytophthora infestans (Mont) de Bary. To study the chemical induction of the resistance, the foliage of several potato cultivars was sprayed with BABA, fosetyl-aluminium or water (as a control treatment). After 3 days the foliage was inoculated with P. infestans. Seven days after inoculation, development of disease symptoms in the foliage was assessed. In postharvest tuber samples, evidence for enhancement of the defence response was evaluated by measuring the protein content of several hydrolytic enzymes as well as the phenol and phytoalexin content. The highest level of protection against late blight was observed when the chemicals were applied at early stages of crop development. An increase in resistance to late blight was also detected in tubers after harvest. There was also an increase in the protein level of beta-1,3-glucanase and aspartic protease as well as in the phenol and phytoalexin content of potato tuber discs obtained from postharvest tubers of treated plants. Thus the protective effect seemed to persist throughout the whole crop cycle. This treatment may offer the possibility of controlling both foliage and tuber blight and could have a major impact in reducing over-winter survival of P. infestans in tubers.

Effect of foliar applications of phosphite on post-harvest potato tubers

“…Seven days after inoculation, phytoalexins were extracted and measured according to Andreu et al (2006).…”

BABA effects on the behaviour of potato cultivars infected by Phytophthora infestans and Fusarium solani

“…When BABA was applied to foliage at early stages of crop development, a protective effect against late blight was obtained. In post-harvest tuber samples, evidence for enhancement of a defence response was evaluated, and an increase in protein level of β-1,3-glucanase and aspartyl protease (StAP1), as well as in phenols and phytoalexins was observed (Andreu et al 2006).…”

Antimicrobial activity of phosphites against different potato pathogens

“…Protection was high against P. infestans, intermediate against F. solani and low against R. solani for all cultivars tested (LOBATO et al 2008b). On the other hand, foliar applications of CaPhi or KPhi provided protection against P. infestans in all cultivars analysed, although protection degree was cultivar-specific (ANDREU et al 2006;LOBATO et al 2008b). Tubers from plants treated in foliage showed a smaller colony diameter of P. infestans and a reduction of the lesion area caused by F. solani and Erwinia carotovora when artificially infected; KPhi had a stronger effect than CaPhi (LOBATO et al 2008a).…”

“…Sporulation and germination of Phytophthora species have also been shown to be suppressed by these biopesticides (COHEN and COFFEY 1986;GARBELOTTO et al 2009). Indirect effects of phosphites are thought to be the activation of plant defence responses (GUEST and BOMPEIX 1990;ANDREU et al 2006;LOBATO et al 2008a).…”