Time Is of the Essence—Early Activation of the Mevalonate Pathway in Apple Challenged With Gray Mold Correlates With Reduced Susceptibility During Postharvest Storage

Abstract

Apple is typically stored under low temperature and controlled atmospheric conditions to ensure a year round supply of high quality fruit for the consumer. During storage, losses in quality and quantity occur due to spoilage by postharvest pathogens. One important postharvest pathogen of apple is Botrytis cinerea. The fungus is a broad host necrotroph with a large arsenal of infection strategies able to infect over 1,400 different plant species. We studied the apple-B. cinerea interaction to get a better understanding of the defense response in apple. We conducted an RNAseq experiment in which the transcriptome of inoculated and non-inoculated (control and mock) apples was analyzed at 0, 1, 12, and 28 h post inoculation. Our results show extensive reprogramming of the apple’s transcriptome with about 28.9% of expressed genes exhibiting significant differential regulation in the inoculated samples. We demonstrate the transcriptional activation of pathogen-triggered immunity and a reprogramming of the fruit’s metabolism. We demonstrate a clear transcriptional activation of secondary metabolism and a correlation between the early transcriptional activation of the mevalonate pathway and reduced susceptibility, expressed as a reduction in resulting lesion diameters. This pathway produces the building blocks for terpenoids, a large class of compounds with diverging functions including defense. 1-MCP and hot water dip treatment are used to further evidence the key role of terpenoids in the defense and demonstrate that ethylene modulates this response.

Genome-Wide Association Analysis Uncovers Genes Associated with Resistance to Head Smut Pathotype 5 in Senegalese Sorghum Accessions

“…In apple (Malus × domestica Borkh. ), a recent study observed extensive transcriptome reprogramming upon inoculation, with 28.9% of expressed genes showing significant differential regulation, and the early activation of the mevalonate pathway correlates with reduced susceptibility, leading to smaller lesion diameters [36].…”

Comprehensive transcriptome analysis of different potato cultivars provides insight into early blight disease caused by Alternaria solani

“…These include simple hydrocarbon terpenes and terpenoids or isoprenoids that are produced via the activation of the cytosolic MVA pathway. Naets et al [53] showed a strong negative correlation between the upregulation of MVA pathway at early time points with the success of B. cinerea infection. From the current study, we identify that all the transcripts involved in the MVA pathway were up-regulated and support the fact that terpenoids are key for plant defense.…”

A metabolome and transcriptome survey to tap the dynamics of fruit prolonged shelf-life and improved quality within Greek tomato germplasm

“…Herein, the terpenoid accumulation and the transcript levels of the underlying pathway genes revealed differences between LSL and SSL, with MEP pathway being clearly stimulated in SSL, and MVA pathway more activated in LSL ( Figure 6 ). Previously, the early transcriptional stimulation of MVA pathway that produces the building blocks for terpenoids, was correlated with reduced susceptibility of apples during postharvest storage ( Roberto et al., 2022 ). Key up-regulated genes in the case of SSL included DXS , DXR , and HDS of MEP pathway, whereas in the case of LSL, two out of the three HMGR transcripts (MVA pathway).…”