Transmission of Colletotrichum truncatum and Macrophomina phaseolina by lima bean seeds

José Monteiro Da Mota,Beatriz Meireles Barguil,Maruzanete Pereira De Melo,Emanoela Maria De Jesus Sousa,Enayra Silva Sousa,Mynor Efraín Munguía García,José Evando Aguiar Beserra Jr

doi:10.1590/0100-5405/180868

José Monteiro Da Mota, Beatriz Meireles Barguil + Show 5 more

Open Access

https://doi.org/10.1590/0100-5405/180868

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Abstract

ABSTRACT The fungi Colletotrichum truncatum and Macrophomina phaseolina are among the main pathogens associated with lima bean seeds in Brazil, and they are the causal agents of anthracnose and charcoal rot, respectively. The aim of this study was to verify the seed-seedling transmission of C. truncatum and M. phaseolina in artificially inoculated lima bean seeds. Potato-dextrose-agar (PDA) media with different hydric potentials were obtained after the addition of mannitol. Isolates of C. truncatum and M. phaseolina were peaked to these media. Forty grams of seeds were distributed over the fungal mycelium, remaining there for different exposure periods, as a function of each treatment: T1: 0.0 MPa without inoculum for 48 h; T2: 0.0 MPa for 48 h; T3: -0.2 MPa for 48 h; T4: -0.4 MPa for 48 h; T5: -0.6 MPa for 72 h; T6: -0.8 MPa for 96 h and T7: -1.0 MPa for 120 h. The seeds were incubated at 25 ºC under a 12-hour photoperiod. Germination in a paper roll, emergence of seedlings in sand and seed health in PDA were evaluated. T4 provided the best conditions to temporarily prevent seed germination, promoting a greater incidence of seeds infected by C. truncatum and a greater percentage of diseased plants. M. phaseolina reduced seed germination, independently of the inoculated treatment. Both fungi were transmitted from the seeds to the seedlings of lima bean, causing symptoms in various aerial parts. C. truncatum and M. phaseolina transmission rate was 83.1% and 76.46%, respectively.

Highlights

Os fungos Colletotrichum truncatum e Macrophomina phaseolina estão entre os principais patógenos associados a sementes de feijão-fava no Brasil, sendo os agentes causais da antracnose e da podridão de carvão, respectivamente
As there is the need for information about seed-seedling transmission of C. truncatum and M. phaseolina, which will subsidize the implementation of appropriate management measures, this study proposed to verify the transmission of these two pathogens from artificially infected lima bean seeds
Osmotic potentials of -0.8 MPa or higher and times from 96 hours onwards normally inhibit the germination of seeds of other plant species, as is the case for cotton seeds (Gossypium hirsutum L.) inoculated with C. gossypii var. cephalosporioides [2] and soybean seeds inoculated with C. truncatum [11]

Summary

Introduction

Os fungos Colletotrichum truncatum e Macrophomina phaseolina estão entre os principais patógenos associados a sementes de feijão-fava no Brasil, sendo os agentes causais da antracnose e da podridão de carvão, respectivamente. Ambos os fungos foram transmitidos das sementes para as plântulas de feijão-fava, causando sintomas em diferentes órgãos aéreos. Anthracnose caused by Colletotrichum truncatum (Schw.) Andrus & Moore frequently occurs and is considered one of the main diseases of lima bean, especially in the Northeastern region, where the weather conditions favor its development [14]. Another fungus that has a deleterious action on leguminous seeds is Macrophomina phaseolina (Tassi) Goid., which can cause failure before and after seedling emergence [1, 8]. The efficiency of the method was demonstrated in studies on the transmission of C. truncatum, Phomopsis sojae Lehman and Sclerotinia sclerotiorum (Lib.) de Bary in soybean (Glycine max (L.) Merrill) seeds [12] and of Fusarium oxysporum f. sp. phaseoli Kendrick et Snyder in common bean [6]

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