Temperature and light intensity interaction on Cercospora coffeicola sporulation and conidia germination

Abstract

Difficulty in obtaining abundant sporulation in culture of many species of Cercospora may be the limiting factor for studies of biology, systematics, and inoculation of the genus. Therefore, it is necessary to understand the nutritional and environmental requirements that influence mycelial growth, sporulation and germination. As it is difficult to obtain conidia of Cercospora coffeicola in vitro, different temperatures (17, 22, 27, and 32 °C) and light intensities (80, 160, 240, and 320 μmol m -2 s -1 ) were evaluated to optimize pathogen sporulation and assess favorable conditions for spore germination, aiming for a strategy of disease control. The dark treatment (0 μmol m -2 s -1 ) was added for sporulation. A significant interaction was found between temperature and light intensity for both variables. The highest sporulation rate of C. coffeicola occurred at a light intensity of 240 μmol m -2 s -1 and air temperature of 22 °C, reaching 5.9x10 6 con mL -1 . Germination was higher at temperature 17 °C and light intensity of 320 μmol m -2 s -1 , reaching 52%. Interaction between light intensity and temperature proved to influence the processes of sporulation and germination of C. coffeicola.Index terms: Environmental variables; Cercospora leaf spot; Coffea arabica. RESUMOObter abundante esporulação em meio de cultura, para muitas espécies de Cercospora, pode ser o fator limitante em estudos de biologia, sistemática e inoculação das espécies do gênero. Por isso, faz-se necessário o entendimento dos requerimentos nutricionais e ambientais, os quais influenciam o crescimento micelial, a esporulação e a germinação Em razão da dificuldade de obter conídios de Cercospora coffeicola in vitro, objetivou-se avaliar diferentes condições de temperatura (17, 22, 27 e 32 °C) e intensidade luminosa (80, 160, 240 e 320 µmol m -2 s -1 ), com o intuito de otimizar a esporulação do patógeno e avaliar as condições favoráveis à germinação dos conídios, visando a táticas de controle da doença. Para a esporulação, adicionou-se o tratamento escuro (0 µmol m -2 s -1 ). Observou-se interação significativa entre temperatura e intensidade luminosa para ambas as variáveis testadas. A maior esporulação de C. coffeicola foi observada na intensidade de 240 µmol m -2 s -1 e na temperatura de 22 °C, atingindo 5,9x10 6 con mL -1 . Com relação à germinação, esta foi maior na temperatura de 17 °C e na intensidade luminosa de 320 µmol m -2 s -1 , atingindo 52%. A interação entre intensidade luminosa e temperatura do ar, influenciou os processos de esporulação e germinação de C. coffeicola.

Identification and Characterization of Causal Agent of Cercospora Leaf Spot Disease of Okra

“…The present study revealed the differences in temperature optima for mycelial growth and asexual fructification of the fungi. The fungal strain had optimal growth at 25⁰C and poor growth at 35⁰C and 4⁰C [35,36]. A research of earlier literature revealed that C. abelmoschi grew well at 25°C in artificial culture while sporulation occurred in the 30°C [18,37].…”

Cercospora species cause pink spot disease on guava fruit in Brazil

“…Shape and length of conidia: After five days of incubation, a conidial suspension of each isolate was made, and a sample was viewed in a haemocytometer. To determine the size, shape, colour and presence of septa (Silva et al, 2016), fifty conidia from each of the monosporic isolates were evaluated. The length and width of the conidia were measured with an Axiocam 503 colour camera (Carl Zeiss) coupled to an AxioLab.…”

“…For each isolate obtained, three mycelial discs of the fungus were placed in autoclaved tubes containing 6 mL of distilled water and 4 mL of V8 tomato juice. For sporulation induction, the tubes were shaken at 200 rpm for 5 days (Silva et al, 2016), after which the contents were poured into Petri dishes containing agar-water medium that remained open in a laminar flow cabinet for 3 days or until the culture medium was dehydrated, with continuous light and room temperature at 25°C. Subsequently, 10 mL of sterile distilled water was aliquoted onto the dehydrated culture medium to obtain a conidial suspension.…”

Agroclimatic zoning for the incidence of brown eye spot on coffee under climate change scenarios

“…Growth, sporulation, and germination of fungi are in uenced by environmental variables (SILVA et al, 2016), mainly agrometeorological elements such as air temperature, relative humidity, and leaf wetness duration since changes in the microclimate favor the increased incidence of diseases (PAIVA et al, 2013). Leaf wetness duration is de ned as the time of accumulation of water on the plant tissue surface (SHIN, PARK, KIM, 2021) and is directly related to the rate of infection and pathogen development (JIAN et al, 2020).…”