The phenylpropanoid pathway affects apple fruit resistance to Botrytis cinerea

Abstract

Apple fruits are rich in phenolic compounds that may enhance resistance to grey mould disease caused by Botrytis cinerea. Using Malus domestica Borkh. cultivars Fuji and Qinguan, we analysed the contents of total phenols, total flavonoids, eight individual phenolic compounds, H2O2 and O2.− as well as the activities of key enzymes in the phenylpropanoid pathway in the flesh of control and B. cinerea‐inoculated fruits. Chlorogenic acid contents increased for a short period in the less susceptible cultivar Qinguan fruits, but decreased in the disease‐susceptible Fuji fruits. Additionally, ferulic acid production was induced in both cultivars in response to B. cinerea. Furthermore, the activities of phenylalanine ammonia lyase, cinnamate 4‐hydroxylase, 4‐coumarate:coenzyme A ligase and cinnamyl alcohol dehydrogenase were differentially induced between the two apple cultivars. Remarkably, the contents of H2O2 and O2.− as well as the activities of enzymes in phenolic metabolism tested in this study were always higher in Qinguan fruits than in Fuji fruits. Our data imply that phenylpropanoid metabolism is closely associated with apple fruit resistance to grey mould disease. These findings may be useful for characterizing the mechanism(s) underlying plant resistance to B. cinerea, with potential implications for the screening of grey mould disease‐resistant apple varieties in breeding programmes.

Review of the Impact of Apple Fruit Ripening, Texture and Chemical Contents on Genetically Determined Susceptibility to Storage Rots

“…In order to obtain properly quantifiable data for a large set of genotypes, experimental inoculations with well-defined inocula have been carried out for several fungi ( Table 3 ). For the wound-mediated storage rots like P. expansum , B. cinerea and M. fructigena , inoculation is usually achieved by wounding and inoculating a number of fruits with conidiospores of the fungus [ 5 , 8 , 15 , 21 , 24 , 25 , 31 , 49 , 56 , 57 ]. Wounding and inoculation can be carried out simultaneously, using a pipette with disposable plastic pipette tips to create one to three inoculation sites on each fruit, allowing large numbers of fruit to be processed in a limited amount of time.…”

Redox Status, JA and ET Signaling Pathway Regulating Responses to Botrytis cinerea Infection Between the Resistant Cucumber Genotype and Its Susceptible Mutant

“…PAL, lignin, coumarins, benzoic acids, stilbenes, and flavonoids/isoflavonoids were important derivatives of phenylpropanoid pathway which exhibited broad-spectrum antimicrobial activity and were believed to help the plants to fight against microbial disease (Dixon et al, 2002). The activities of PAL, cinnamate 4-hydroxylase (C4H) and CAD enzyme were differentially induced between the two apple cultivars in response to B. cinerea (Ma et al, 2018). In addition, the phenylpropane polymer lignin provided strength to the cell walls for preventing direct penetration of the fungus (Pesquet et al, 2019).…”

Antifungal Starch–Gellan Edible Coatings with Thyme Essential Oil for the Postharvest Preservation of Apple and Persimmon

“…Lesion diameters (disease severity, mm) were measured after 7 and 12 days of incubation. Disease incidence (%) was expressed as the percentage of infected wounds out of the total number of inoculated wounds per replicate and treatment [6].…”

“…In fruit that are often stored for extended periods such as apples, field infections that remained latent can resume growth during storage, when the pathogen takes advantage of fruit maturity and environmental conditions and the disease develops (low temperatures and high humidity). In this sense, B. cinerea is very well adapted to low temperatures, and it is even able to grow at 0 • C [6]. Infection starts with a darker circular area where the fruit tissues are softer than the other fruit parts, and subsequent abundant sporification, whose colour ranges from white to gray, can develop from the site of infection in conditions of ambient temperature and high humidity [7].…”