Oxidative burst and the activity of defense-related enzymes in compatible and incompatible tomato-Alternaria solani interactions

Abstract

The production of reactive oxygen species (ROS), hypersensitive response (HR), and the activity of the enzymes guaiacol peroxidase, catalase, polyphenol oxidase, β-1,3-glucanase and chitinase, were studied in leaves of resistant [CNPH 1287 (Solanum habrochaites syn. Lycopersicon hirsutum)] and susceptible [Santa Cruz Kada (S. lycopersicum syn. L. esculentum)] tomato genotypes inoculated with Alternaria solani. Leaves were collected at the time of inoculation and at 4, 8, 12, 24, 48, 72, 96 and 120 hours post inoculation. Conidia germination occurred equally onto the leaf surface in both genotypes and germination tubes grew without apparent orientation. Lesion frequency was lower in CNPH 1287, and it was the consequence of a lower number of appressoria formed in that genotype. ROS were observed in low frequency in both genotypes. HR was observed in penetrated epidermal host cells also in both genotypes. It seems that ROS and HR would not contribute to the resistance of S. habrochaites to A. solani in this study. The activity of guaiacol peroxidase, polyphenol oxidase, β-1,3-glucanase and chitinase was significantly increased in the resistant genotype. These results suggest that defense-related enzymes but no oxidative burst play a role in the defense response of S. habrochaites to A. solani.

Antioxidant activity in safflower (Carthamus tinctorius L.) cultivars under the pathogenesis of foliar fungal disease complex

“…Sacc. The decreased activity of CAT in infected leaves of all cultivars over healthy leaves suggests that CATwas not operating as H 2 O 2 -scavenging enzyme but favors the H 2 O 2 accumulation as indicated by Balbi-Peña et al (2014) which may be involved in defence against foliar fungal disease complex.…”

PRODUCTIVE POTENTIAL OF THE CHERRY TOMATO GENOTYPE GROUP BEFORE INFECTION BY Alternaria tomatophila

“…Other studies have confirmed that temperatures in the range 25-32°C, favor the development of black spots on tomato and epidemic disease (BALBI-PEÑA et al, 2006;SALUSTIANO et al, 2006). The relative humidity ranged from 60 to 90% during the test which may have promoted the presence of free water on the leaf surface, a fundamental factor for germination, infection and sporulation.…”

“…The relative humidity ranged from 60 to 90% during the test which may have promoted the presence of free water on the leaf surface, a fundamental factor for germination, infection and sporulation. Researchers demonstrated that A. solani occurs in the infection process in a 14-26°C temperature range, with a relative humidity around 100% during the first 24 h, establishing conditions for the development of the epidemic (ROTEM, 1994;PAUL et al, 2004;BALBI-PEÑA et al, 2006;SALUSTIANO et al, 2006). Such conditions are evident from the 51 DAT indicating a significant increase in disease severity genotypes (Figure 2).…”

Exploring the mechanisms of endophytic bacteria for suppressing early blight disease in tomato (Solanum lycopersicum L.)

“…To better understand the mechanism of resistance, the expression β-1,3 -glucanase gene was investigated in all EC-treated tomato plants in our study. This gene encodes one of the pathogenesis-related proteins (PR protein) that are included in several plant-pathogen interactions and associated with defense against plant diseases ( Sharifi et al, 2012 ; Balbi-Peña et al, 2014 ). Plant β - 1 ,3-glucanases play an important role in controlling the outcome of both symbiotic and antagonistic plant-microbe interactions by destroying non-self-glucan structures.…”