Effect of temperature of production of Botrytis allii conidia on their pathogenicity to harvested white onion bulbs

Abstract

Botrytis allii colonies incubated at low temperatures have been reported to produce larger conidia that germinate faster and give rise to longer germ-tubes than those grown at room temperature. The present study compared the effect of conidia produced at 20ЊC and at 0 and -2ЊC on their pathogenicity to artificially inoculated white onion bulbs, and the effect of conidial concentration (5 × 10 3 and 5 × 10 4 conidia/mL) on disease incidence, lesion area, incubation and latent period during storage at 20, 5 and 0ЊC. At all storage temperatures and periods tested conidia produced at -2ЊC caused a higher disease incidence and larger areas of rot than those produced at higher temperatures. When the conidial production temperature was raised to 20ЊC, the duration of incubation on the bulbs inoculated with 5 × 10 4 conidia/mL was more than doubled during storage at 0ЊC, tripled at 5ЊC, and took 50% longer at 20ЊC. The incubation period was not significantly affected by conidial concentration at 20ЊC, and only slightly at 5 and 0ЊC, but at low temperatures the latent period was longer because of the delay induced in sporulation. These data are consistent with the packers' opinion that cross-infection of spring onions by long-term refrigerated onions in grading lines caused earlier and heavier rotting.

The allergenicity of Aspergillus fumigatus conidia is influenced by growth temperature

“…Growth and sporulation temperature may significantly affect environmental allergen exposure given that multiple allergenic proteins exist for important allergenic fungi such as Cladosporium herbarum , Alternaria alternata and Penicillium spp . (Bertolini and Tian, 1997) and that exposure occurs at multiple temperatures in indoor/outdoor environments, seasons, and climates. This study establishes a link between sporulation temperature and allergenicity for an important allergenic fungus.…”

“…In addition, numerous studies on spore development and pathogenicity suggest that environmental conditions during spore development result in physiological changes and differential gene expression in fungal spores (Abbas et al . 1995; Bertolini and Tian, 1997; Misaghi et al ., 1978; Phillips, 1982; Wolf et al, 2010). Since many fungal species including A. fumigatus have multiple, unrelated allergenic proteins, environmental factors during sporulation may affect the regulation of genes encoding for these proteins and therefore impact the per spore allergenicity (determined here as the capacity to bind with human IgE from patients sensitized to A. fumigatus allergens) (Miguel et al ., 1996)).…”

Gene expression of indoor fungal communities under damp building conditions: Implications for human health

“…Fungi present on building materials with elevated water availability (measured as water activity, a w ) may express genes leading to an enhanced, but largely unaccounted for, ability to cause disease in humans. Prior pure culture fungal studies demonstrate that environmental factors including temperature and the elevated presence of NO 2 , CO 2 , and O 3 during spore development result in physiological changes, differential gene expression, and modulation in pathogenicity and allergenicity . Increasing water activity levels in growth media have resulted in elevated emissions of mycotoxins and volatile organic compounds (VOCs) from Aspergillus spp.…”

Effects of Long Term Exposure to High‐CO2 During Storage at 0°C on Biology and Infectivity of Botrytis cinerea in Red Chicory

“…Bacteria become particularly damaging during storage at above zero temperatures and during shelf‐life. The progress of the infections caused by Botrytis species are greatly reduced by low temperature, although the fungus is able to grow even at −4°C (Coley‐Smith et al., 1980; Tian and Bertolini, 1995; Bertolini and Tian, 1997; Bertolini et al., 1998). The fungus causing rots of leaf blades, originated from latent infection at picking time and from wounds produced during postharvest handling.…”