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Detection of latent infections caused by Botrytis cinerea in flowers and fruits on apple using conventional and molecular methods in MauleRegion,Chile

Enrique Ferrada: Universidad de Talca

<div>The major fungal problem in apple fruits in Chile is the calyx-end rot caused by <em>Botrytis cinerea</em>, during pre and post-harvest. The objective of this study was to determine the most effective method for early detection of latent infections caused by <em>B. cinerea</em>, using conventional and molecular methods on apples. Plant material of cvs. Cripps Pink and Fuji were collected from flowers (full bloom) and fruits (during fruit set and harvest) in three commercial orchards located in the Maule Region, Chile. Three conventional methods were assessed: i) ONFIT (overnight freezing incubation at -20ºC), ii) immersion in paraquat, and iii) immersion in distillate sterile water (control), varying the times and concentrations, according to the sample (flower, fruit set and mature fruits). Molecular detection assessed conventional PCR, with specific primer of <em>B. cinerea</em>, and qPCR by using a TaqMan probe, describe previously. Results indicate that in flowers and fruit set, the most effective treatment for detection of <em>B. cinerea</em> was ONFIT, while immersion in paraquat was the most effective method with mature fruits. Conventional PCR and qPCR allow fungal detection in all flowers and fruits analyzed, with qPCR indicated variable inoculum charges according to the cultivar and locality. The use of these methods could allow to determine the inoculum pressure present in the apple orchards and estimating the prevalence of the disease <em>in situ</em>.</div>