Analysis of Cryptic, Systemic Botrytis Infections in Symptomless Hosts

Area of Science:

• Plant Pathology
• Mycology
• Microbial Ecology

Background:

• Botrytis species are widely recognized as aggressive, necrotrophic plant pathogens.
• However, these fungi are also frequently isolated from the internal tissues of apparently healthy host plants.

Purpose of the Study:

• To investigate the prevalence and characteristics of cryptic infections caused by Botrytis species in various plant hosts.
• To understand the life cycle and pathogenic potential of these endophytic Botrytis isolates.

Main Methods:

• Isolation and identification of Botrytis species from internal tissues of asymptomatic plants.
• Molecular typing (genotyping) to track fungal spread within hosts.
• Inoculation experiments to assess the pathogenic potential of cryptic isolates on different hosts.

Main Results:

• Botrytis species were frequently found as cryptic infections in multiple host tissues, with prevalence varying by host, tissue, and year.
• Botrytis cinerea and Botrytis pseudocinerea were common cryptic species, alongside novel phylogenetic lineages.
• Visible disease symptoms and sporulation only occurred under host stress (maturity, senescence, or environmental stress).
• Cryptic infections showed no apparent negative impact on host growth, and some isolates retained pathogenicity.

Conclusions:

• Several Botrytis species commonly exist in a cryptic, endophytic state within healthy plants, a phenomenon largely overlooked.
• These cryptic infections do not require disease development on healthy hosts to complete their life cycles.
• Cryptic Botrytis isolates may possess pathogenic potential, indicating a complex interaction with their hosts that doesn't necessarily involve overt disease in asymptomatic plants.