SAPROBIC FUNGI AS BIOCONTROL AGENTS OF HALO BLIGHT (Pseudomonas syringae pv. garcae) IN COFFEE CLONES

Abstract

Halo blight caused by Pseudomonas syringae pv. garcae is a limiting disease in coffee production. There are few efficient commercial products on the market to control this disease, and therefore, the prospection of different biocontrol agents is a promising alternative. The objectives in this study were (i) to select saprobic fungi with the potential to control halo blight in coffee clones, and (ii) to evaluate the contributions of induced resistance as control mechanisms. Plants were sprayed with Gonytrichum chlamydosporium, Phialomyces macrosporus, and Moorella speciosa 7 d before inoculation with Pseudomonas. syringae pv. garcae. The area under the halo blight progress curve (AUDPC) and plant growth parameters were evaluated. M. speciose and G. clamydosporium did not reduce the AUDPC and even reduced plant growth in none of the trails compared to the water control. P. macrosporus consistently reduced AUDPC by 42-72% and increased plant height by 40%. Thereafter, the contributions of induced resistance was evaluated for the P. macrosporus, selected as the most promising biocontrol agent.. In order to determine induced resistance, phenylalanine ammonia lyase (PAL), peroxidase (POX), and ascorbate peroxidase (APX) activity of plant leaves were measured at two time points after stress challenge. Enzyme activity evaluation demonstrated high activity of POX and PAL at seven days after treatment with the saprobe, and high APX activity after 14 days. The results of this study indicate that P. macrosporus has the potential to be used in the management of coffee halo blight in seedling production, and one mechanism likely involved is induced resistance.

Antagonism of saprobe fungi from semiarid areas of the Northeast of Brazil against Sclerotinia sclerotiorum and biocontrol of soybean white mold

“…Phialomyces macrosporus is reported in literature as a potential resistance inducer in coffee plants against Pseudomonas syringae pv. garcae (Botrel et al, 2018) and Colletotrichum gloeosporioides (Rodríguez et al, 2016) and in eucalyptus plants against Puccinia psidii Winter (Pucciniales: Pucciniaceae) (Pierozzi, 2013).…”

“…A. C. Almeida, Izabel, & Gusmão, 2011;Leão-Ferreira, Pascholati, Gusmão, & Castañeda Ruiz, 2013;Santa Izabel & Gusmão, 2018). Some of these saprobes were being used as potential biological control agents and resistance inducers (Resende, Milagres, Rezende, Aucique-Perez, & Rodrigues, 2015;Barros, Fonseca, Balbi-Peña, Pascholati, & Peitl, 2015;Rodríguez et al, 2016;Peitl et al, 2017;Ribeiro et al, 2018;Botrel et al, 2018).…”

Phialomyces Macrosporus Reduces Cercospora Coffeicola Survival on Symptomatic Coffee Leaves

“…In addition, other authors have reported the use of P. macrosporus as a biocontrol agent in coffee diseases. Botrel et al (2018) observed a reduction in the severity of coffee halo blight of up to 72% when the seedlings were previously treated with the fungus P. macrosporus. Rodríguez et al (2016) observed similar results in the control of C. gloeosporioides in coffee seedlings treated with P. macrosporus.…”

“…Furthermore, they can withstand sudden variations in temperature and humidity and sustain biological control in such environment, which turn them promising biological control agents (Köhl et al, 1995). Currently, saprobe fungi have been used as a biological agent for coffee disease control (Botrel et al, 2018;Rodríguez et al,2016). Therefore, we hypothesize that saprobe fungi might inhibit C. coffeicola growth in crop residues and its production antifungal compounds and cell-wall degrading enzyme may play a role in the pathogen displacement.…”

Bioproducts and Homeopathy in Lasiodiplodia Rot (Lasiodiplodia sp.) Control and Development of Passion Fruit Seedlings

“…The potential of saprobic fungi, such as Phialomyces macrosporus, in disease control has been reported against coffee bacterial blight (Pseudomonas syringae pv. garcae), with a 42% reduction in disease severity and a 40% increase in seedling height (Botrel et al 2018).…”