Morphological Characterization of Corynespora cassiicola Isolates in Culture Media

Jacqueline Dalbelo Puia,Estela Mariani Klein,Marcelo Giovanetti Canteri,Emily Danila De Almeida,Sandra Cristina Vigo,Adriano Thibes Hoshino

doi:10.5539/jas.v13n11p74

Abstract

Corynespora cassiicola threatens soybean and cotton production in Brazil. The objective of this study was to evaluate cultural and morphological aspects of C. cassiicola isolated from soybean and cotton of different Brazilian regions, in culture media. The isolates were grown in PDA (Potato Dextrose Agar) and V8 juice agar media. The characteristics evaluated were: color, aspect, and growth rate of mycelia, as well as production and dimension of conidia, and number of septa per conidium. Culture media and isolates were compared using the Kruskal-Wallis or Tukey&rsquo;s test at 5% significance level. The mycelia of the isolates were predominantly dark gray and light brown. C. cassiicola isolates grew better in V8 juice agar medium, presenting a higher mycelial growth rate. In PDA medium, the production of conidia was higher in isolates from cotton, compared with soybean isolates. There was great variation in the production of conidia in V8 juice agar medium, regardless of the host origin. Conidia length and width varied for isolate and culture medium. The isolates of C. cassiicola coming from cotton presented a higher number of septa per conidium when grown in PDA medium. The morphological aspects of C. cassiicola vary depending on the host of origin and the culture medium.

Highlights

The fungus Corynespora cassiicola Berk. & M
Severe epidemics of Corynespora cassiicola have been recorded in the USA, Brazil, and Argentina, where soybean and cotton are grown in crop rotation (Galbieri et al, 2014), leading to an increasing incidence of target spot in the last harvests of these crops (Sumabat et al, 2018; Godoy et al, 2020)
Great variation was observed in the pigmentation of the eight C. cassiicola isolates grown in Potato Dextrose Agar (PDA) and V8 juice agar culture media (Table 2 and Figure 2)

Summary

Introduction

Curtis (Wei, 1950), present in countries with tropical and subtropical climates, causes diseases in more than 530 plant species belonging to 400 different genera (Farr et al, 2019) This fungus has a wide range of economically important hosts including soybean (Glycine max) (Seaman et al, 1965) cotton (Gossypium hirsutum) (Fulmer et al, 2012), common bean (Phaseolus vulgaris) (Mendes et al, 1998), papaya (Carica papaya) (Qi et al, 2011), cucumber (Cucumis sativum) (Cutrim & Silva, 2003), pepper (Capsicum annuum) (Shimomoto, 2008) rubber tree (Hevea brasiliensis) (Qi et al, 2011), and tomato (Lycopersicon esculentum) (Lopes & Ávila, 2005). The severely affected leaves fall prematurely (Sinclair & Backman, 1989)

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