Contrast Between Orange- and Black-Colored Sclerotial Isolates of Botrytis cinerea: Melanogenesis and Ecological Fitness

Abstract

Botrytis cinerea usually produces grayish mycelia and conidia as well as black-colored sclerotia (BS) due to accumulation of melanin. An isolate (XN-1) of B. cinerea producing orange-colored sclerotia (OS) on agar media was obtained from an orange-colored apothecium of an uncultured soil fungus. Whether or not the OS B. cinerea occurs on plants and how they differ from the BS isolates in melanogensis and ecological fitness remained unknown. This study, for the first time, confirmed the presence of the OS B. cinerea in strawberry and tomato plants that were surveyed in Hubei Province of China. Only five OS isolates were obtained from a total of 2,031 isolates surveyed from the two crops. The OS isolate XN-1 was compared and contrasted with the BS isolate B05.10 in sclerotial melanogenesis and ecological fitness. Sclerotial melanogenesis was evident in B05.10 but was deficient in XN-1. The OS were more susceptible to the two mycoparasites Trichoderma koningiopsis and Clonostachys rosea than the BS. The percentage of viable sclerotia after the mycoparasitism study was significantly (P < 0.01) lower in OS (21%) than in BS (48%). This study also reaffirmed the importance of melanization for survival of B. cinerea sclerotia.

Characterization of fungicide sensitivity profiles of Botrytis cinerea populations sampled in Lombardy (Northern Italy) and implications for resistance management

“…This could indicate a slight delay in the production of sclerotia by these phenotypes that, however, formed sclerotia for the most part of the isolates at 20 dai. Sclerotia are formed between 6 and 28 dai and are necessary for the pathogen survival during unfavorable conditions, such as the absence of the host during the winter, even if they can be one of the ways the pathogen adopts for surviving in vineyards . Statistical analysis of AUDPC values indicated that sensitive and resistant phenotypes are characterized by analogous abilities to colonize leaves and berries.…”

A Single-Nucleotide Deletion in the Transcription Factor Gene bcsmr1 Causes Sclerotial-Melanogenesis Deficiency in Botrytis cinerea

“…However, importance of the sclerotia as the primary infection source remains controversial in the life cycle of B. cinerea , as they are not frequently observed in infected tissues of many diseased plants (Williamson et al, 2007 ). Zhou et al ( 2018 ) reported six field isolates of B. cinerea producing orange-colored sclerotia (OS). The sclerotia of the OS isolate XN-1 were found to be deficient in sclerotial melanogenesis, compared to the black-colored sclerotia produced by isolate B05.10 of B. cinerea (Zhou et al, 2018 ).…”

“…Zhou et al ( 2018 ) reported six field isolates of B. cinerea producing orange-colored sclerotia (OS). The sclerotia of the OS isolate XN-1 were found to be deficient in sclerotial melanogenesis, compared to the black-colored sclerotia produced by isolate B05.10 of B. cinerea (Zhou et al, 2018 ). The orange-colored sclerotia were greatly reduced for survival, compared to the black-colored sclerotia.…”

“…The orange-colored sclerotia were greatly reduced for survival, compared to the black-colored sclerotia. Meanwhile, Zhou et al ( 2018 ) also found that the OS B. cinerea rarely occurred in nature. Therefore, DHN melanin deposition on the sclerotia of B. cinerea plays an important role in ecological fitness of sclerotia.…”

“…It usually produces black-colored sclerotia (BS) due to deposition of 1,8-dihydroxynaphthalene melanin in sclerotial melanogenesis. Our previous study (Zhou et al, 2018 ) reported six B. cinerea isolates producing orange-colored sclerotia (OS) with deficiency in sclerotial melanogenesis. Comparison of ecological fitness (conidia, mycelia, sclerotia), natural distribution, and melanogenesis of selected BS and OS isolates suggests that sclerotia play an important role in the disease cycle caused by B. cinerea .…”