Initial studies of the response of rubber tree seedlings treated with saprobic fungi from the semiarid region of Northeast Brazil to anthracnose

Abstract

Anthracnose, caused by fungi of the genus Colletotrichum, is present in the main areas where rubber trees (Hevea brasiliensis) are planted. Thus, considering that biological agents can be an alternative for disease control, the present study aimed to carry out initial studies to investigate the response of rubber tree seedlings inoculated with Colletotrichum and treated with saprobes fungi from the semiarid region of Northeast Brazil (Curvularia eragrostidis, Memnoniella levispora, Myrothecium roridum and Phialomyces macrosporus). Seedlings of the rubber tree clone RRIM600 were sprayed with biocontrol agents as preventive and curative treatments seven days before and after C. tamarilloi inoculation, respectively. Assessments included plant response to disease expression based on percentage of symptomatic area on treated leaves, percentage of graft death, and percentage of apical death in seedlings 30 days after inoculation with C. tamarilloi. In addition, the enzymes peroxidase and phenylalanine ammonia lyase (PAL) had their activity quantified by their association with plant resistance to pathogens. The fungus C. eragrostidis had the best result in controlling anthracnose when applied as a preventive treatment, showing 10% less disease than the untreated plant. The same was observed for the fungus P. macrosporus when used in the curative form. These fungi also reduced the graft death. In these cases, PAL activity was higher and may be linked to the induction of resistance against the pathogen. The peroxidase activity was not expressive for treatments with saprobic fungi in the periods studied. Therefore, among the tested fungi, C. eragrostidis and P. macrosporus are promising for the control of anthracnose, deserving further studies.

Genome-Wide Identification and Expression Profile Analysis of the Phenylalanine Ammonia-Lyase Gene Family in Hevea brasiliensis

“…Differently from their response to powdery mildew, except for HbPAL3 and HbPAL6 with no change in expression, all other HbPALs were down-regulated in anthracnose-infected leaves. Bergamini Lopes et al [40] showed that the activity of PAL was enhanced after treatments that strengthened anthracnose resistance in rubber trees. Therefore, we speculate that the susceptibility to anthracnose may be related to the decrease in HbPAL expression in the rubber tree.…”

The Diseases and Pests of Rubber Tree and Their Natural Control Potential: A Bibliometric Analysis

“…velezensis secreted HN-2 elicitors into rubber leaves; these elicitors enhance plant immunity by suppressing HbLFG1 and elevating the activity of antioxidant enzymes such as ascorbate peroxidase, peroxidase, catalase, and superoxide dismutase [52]. When treated with the saprobic fungal antagonists Curvularia eragrostidis and Phialomyces macrosporus, phenylalanine ammonia lyase activity was higher in rubber tree, which enhanced plant resistance against the anthracnose pathogen C. tamarilloi [39]. Class III peroxidases are associated with defense responses to P. meadii; their activity in rubber leaves can be induced by Alcaligenes sp.…”