Cosmos white rot: First characterization, physiology, host range, disease resistance, and chemical control

Abstract

A new disease of Cosmos sulphureus Cav. causing external and internal stem discoloration, premature death, and wilting was observed in 27.8% of plants with an average disease severity rating of 4.4 in Gazipur, Bangladesh.Morphological, pathological, and molecular analyses identified the isolated fungus as Sclerotinia sclerotiorum (Lib) de Bary, the causative agent of white rot disease. The optimum growth and sclerotium formation of S. sclerotiorum occurred at 20°C and pH 5.0, while glucose, peptone, yeast extract, casein, and ascorbic acid were the appropriate nutrient sources. Furthermore, mycelial growth and sclerotial development were favored in media containing potassium, magnesium, calcium, and sodium. As many as 20 plant species of 10 families;

Sclerotinia sclerotiorum (Lib.) de Bary: Insights into the Pathogenomic Features of a Global Pathogen

“…During humid conditions, infected plant parts often show signs of S. sclerotiorum , such as whitish, fluffy mycelium and big, irregularly shaped sclerotia on the host surface or embedded in the infected tissues ( Figure 1 D,E). Sclerotia are variable in shape but are generally globose to cylindrical, ranging from 2.0 to 20.0 mm [ 2 , 5 , 17 ]. On PDA, colonies rapidly expand and have white, cottony, aerial mycelia with a salmon-buff hue on the back.…”

“…The medulla, the innermost section, is embedded in a fibrillar matrix and is mainly made of proteins and glucans. Three phases of sclerotial formation have been identified: the first phase is initiation or commencement (hyphae aggregate to generate a white sclerotial mass or initials); the second phase is development (sclerotial initials increase in size); and the third phase is maturation (surface delimits, melanin deposits in peripheral rind cells, and internal cells consolidate) [ 2 , 5 , 17 ]. Several factors, including many dietary elements, environmental changes, secondary messengers, and primary metabolism, affect sclerotial formation and development.…”

“…Sclerotia are typically formed when mycelial development confronts a nutrient-limited environment [ 17 ]. Glucose, yeast extract, peptone, ascorbic acid, and casein are the most suitable sources of nutrients for sclerotial formation in S. sclerotiorum [ 2 , 5 , 17 ]. Moreover, sclerotial development is favored in media enriched with calcium, magnesium, potassium, and sodium [ 2 ].…”

“…This fungus is widely distributed throughout temperate, tropic, and arid regions [ 1 ]. The disease caused by this fungal pathogen is named by various terms, including white mold, watery soft rot, cottony rot, cottony soft rot, drop, stem rot, bloom blight, crown rot, and Sclerotinia rot [ 2 ]. Among these terms, white mold is most frequently used to refer to the disease caused by S. sclerotiorum .…”

“…S. sclerotiorum possesses profound parasitic abilities and can colonize nearly all plant tissues with its mycelia. Critically, this fungus does not have a specificity for any particular host and infects over a few hundred monocotyledonous and dicotyledonous plant species, including some economically important crops, flowers, and weeds [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. While S. sclerotiorum is primarily a plant parasite, a recent study has found that it can also grow endophytically in monocots, including rice ( Oryza sativa ), wheat ( Triticum aestivum ), maize ( Zea mays ), barley ( Hordeum vulgare ), and oat ( Avena sativa ) [ 10 ].…”