Resistance inducers and biochemical mechanisms in the control of anthracnose in cowpea

Abstract

J. M. Silva, M. B. C. L. Medeiros, J. T. C. Oliveira, E. V. Medeiros, C. M. Souza-Motta, and K. A. Moreira. 2018. Resistance inducers and biochemical mechanisms in the control anthracnosis on cowpea. Cien. Inv. Agr. 45(3): 290-300. Different responses are observed in plants after infection by pathogens. The usage of systemic inducers, whether biotic or abiotic,has the function to increase the enzymatic production of the plant defense system. In that sense, our present research aims to evaluate the disease severity of anthracnose in the cowpea cultivar "sempre-verde" infected with Colletotrichum lindemuthianum URM 5771 and subjected to both biotic and abiotic resistance inducers, as well as evaluate the enzymatic activity of plant defense. The experiment was performed in a greenhouse with a completely randomized splitplot design with six treatments: four abiotic plant resistance inducers, acibenzolar-S-methyl, β-aminobutyric acid, chitosan, and salicylic acid; one biotic inducer, the filamentous fungi Trichoderma aureoviride URM 5158; and a control with only water. The plant leaves were sampled at four time points, 4, 8, 12 and 20 days after inoculation with the plant pathogen, to measure the enzymatic activity of β-1,3-glucanase, catalase, peroxidase, polyphenoloxidase, and protease. The abiotic inducers acibenzolar-S-methyl, β-aminobutyric acid, and chitosan and the biotic inducer presented the highest potential in reducing the anthracnose caused by C. lindemuthianum URM 5771 in cowpea plants by showing the lowest values of injury severity over time. The disease progression showed a proportionate shift in enzymatic activity in that the inducers salicylic acid and T. aureoviride URM 5158 promoted the highest enzymatic activity when compared to the other inducers. High correlations between the enzymatic activity of peroxidase and polyphenoloxidase and anthracnose severity were observed in cowpea plants. The use of abiotic and biotic resistance inducers presents high potential for anthracnose control in cowpea plants; however, more studies should be carried out covering different environments, plant cultivars and climatic conditions.

Laminarin Induces Defense Responses and Efficiently Controls Olive Leaf Spot Disease in Olive

“…In a previous study, acibenzolar-S-methyl significantly reduced OLS severity by an average of 48-68% compared to the untreated control [8]. Numerous previous studies have shown that ASM is a potent inhibitor of diseases caused by both fungal and bacterial pathogens on several hosts [30][31][32]. The increased resistance of ASM-treated plants has been associated with a higher activation rate of principal antioxidant enzymes, such as peroxidase, superoxide dismutase, catalase and ascorbate peroxidase, an enhancement of polygalacturonase-inhibiting proteins, and the increased production of PR-proteins [13].…”

The Influence of Resistance Chemical Inducers Against Anthracnose on Cucumber and Pepper Plants

“…To mitigate the adverse effects of fungicides on humans and the environment, chemical elicitors have been explored as an alternative approach for managing diseases caused by Colletotrichum spp. across various plant hosts (Arora, 2013;Li et al, 2016;da Silva et al, 2018). Therefore, the objectives of this study were: a, to assess the impact of boric acid, ascorbic acid, and salicylic acid on the linear growth and sporulation of C. orbiculare and C. acutatum in cucumber and pepper plants under in vitro conditions; b, to evaluate the activity of oxidative enzymes and total phenolic compounds to elucidate the potential correlation between their activity and the induced defense mechanisms; c. to analyze micrographs obtained through scanning electron microscopy (SEM) to examine the effects of salicylic acid on C. orbiculare and C. acutatum; d, to investigate the effectiveness of salicylic acid in controlling anthracnose in cucumber and pepper plants under glasshouse condition.…”