Intact salicylic acid signalling is required for potato defence against the necrotrophic fungus Alternaria solani

Abstract

Key Message Using disease bioassays and transcriptomic analysis we show that intact SA-signalling is required for potato defences against the necrotrophic fungal pathogen Alternaria solani. Abstract Early blight, caused by the necrotrophic fungus Alternaria solani, is an increasing problem in potato cultivation. Studies of the molecular components defining defence responses to A. solani in potato are limited. Here, we investigate plant defence signalling with a focus on salicylic acid (SA) and jasmonic acid (JA) pathways in response to A. solani. Our bioassays revealed that SA is necessary to restrict pathogen growth and early blight symptom development in both potato foliage and tubers. This result is in contrast to the documented minimal role of SA in resistance of Arabidopsis thaliana against necrotrophic pathogens. We also present transcriptomic analysis with 36 arrays of A. solani inoculated SA-deficient, JA-insensitive, and wild type plant lines. A greater number of genes are differentially expressed in the SA-deficient mutant plant line compared to the wild type and JA-insensitive line. In wild type plants, genes encoding metal ion transporters, such as copper, iron and zinc transporters were upregulated and transferase-encoding genes, for example UDP-glucoronosyltransferase and Serine-glyoxylate transferase, were downregulated. The SA-deficient plants show upregulation of genes enriched in GO terms related to oxidoreductase activity, respiratory chain and other mitochondrial-related processes. Pathogenesis-related genes, such as genes encoding chitinases and PR1, are upregulated in both the SA-deficient and wild type plants, but not in the JA-insensitive mutants. The combination of our bioassays and the transcriptomic analysis indicate that intact SA signalling, and not JA signalling, is required for potato defences against the necrotrophic pathogen A. solani.

Green Leaf Volatile Confers Management of Late Blight Disease: A Green Vaccination in Potato

“…Previous studies have reported this biphasic SA-and JA-mediated basal defense response against P. infestans in potato plants [99,100]. A recent study indicated that intact SA-signaling is essential for potato defenses against the necrotrophic pathogen Alternaria solani [101]. This contrasts with the documented minimal impact of SA-dependent defense responses of the model plant A. thaliana on necrotrophic pathogens that are essential for resistance to biotrophic and hemibiotrophic pathogens [102].…”

Transcriptome analysis of potato leaves in response to infection with the necrotrophic pathogenAlternaria solani

“…In the transcriptome data, after infection with Aso, the genes related to pathogen infection (such as NPR1, PR-1, STH-21) downstream of SA are significantly activated ( Supplementary Table S2). A recent study used microarray to characterize potatoes in order to cope with Aso infection, a complete SA signal transduction pathway is necessary [18]. Although our data shows that SA content did not change significantly after Aso infection, but its downstream defense response was significantly activated, so our study provide a more complete evidence, enrich the SA pathway response mechanism after the potato in response to infection by Aso.…”

“…After inoculated potato plants in the greenhouse, we found that the potato leaves quickly turned yellow and entered the stage of senescence and death after Aso infection. Although several studies have reported on the pathogenic mechanism of Aso [18,19], we hope that through a comprehensive analysis of the host's transcriptome response during the process of infection (from successful colonization to leaf necrosis), we can gain insight into the pathophysiology of the disease and other aspects.…”

“…In another study, used disease bioassays and transcriptomic analysis showed that intact SA-signalling is required for potato defences against the necrotrophic fungal pathogen Alternaria solani [18]. Although several studies have been carried out to analyze the interaction between Alternaria solani and host plants [17,18,19], this study is the first global transcriptome analysis of potato infected by Alternaria solani.…”

Comparative Studies Between Treatments of Potato Tubers Slices with Three Amino Acids and Treatment with Salicylic Acid or Jasmonic Acid on the Infection by Dry Rot (Fusarium solani)

“…In the first case, jasmonic acid or its derivatives are triggers mediating plant resistance to diseases. However, plant resistance to biotrophs greatly depends upon salicylic acid or its derivatives (McDowell and Dangl, 2000;Kunkel and Brooks, 2002;Glazebrook, 2005;Verhagen et al, 2006;Guerreiro et al, 2016;Brouwer et al, 2020 andGomi, 2020).…”