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Title: Transcriptome‐based analyses of phosphite‐mediated suppression of rust pathogens Puccinia emaculata and Phakopsora pachyrhizi and functional characterization of selected fungal target genes

Phosphite (Phi) is used commercially to manage diseases mainly caused by oomycetes, primarily due to its low cost compared with other fungicides and its persistent control of oomycetous pathogens. We explored the use of Phi in controlling the fungal pathogensPuccinia emaculataandPhakopsora pachyrhizi, the causal agents of switchgrass rust and Asian soybean rust, respectively. Phi primes host defenses and efficiently inhibits the growth ofP. emaculata,P. pachyrhiziand several other fungal pathogens tested. To understand these Phi‐mediated effects, a detailed molecular analysis was undertaken in both the host and the pathogen. Transcriptomic studies in switchgrass revealed that Phi activates plant defense signaling as early as 1 h after application by increasing the expression of several cytoplasmic and membrane receptor‐like kinases and defense‐related genes within 24 h of application. Unlike in oomycetes,RNAsequencing ofP. emaculataandP. pachyrhizidid not exhibit Phi‐mediated retardation of cell wall biosynthesis. The genes with reduced expression in either or both rust fungi belonged to functional categories such as ribosomal protein, actin,RNA‐dependentRNApolymerase, and aldehyde dehydrogenase. A fewP. emaculatagenes that had reduced expression upon Phi treatment were further characterized. Application of double‐strandedRNAs specific toP. emaculatagenes encoding glutamateN‐acetyltransferase and cystathionine gamma‐synthase to switchgrass leaves resulted in reduced disease severity uponP. emaculatainoculation, suggesting their role in pathogen survival and/or pathogenesis.

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Author(s) / Creator(s):
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Publisher / Repository:
Date Published:
Journal Name:
The Plant Journal
Page Range / eLocation ID:
p. 894-904
Medium: X
Sponsoring Org:
National Science Foundation
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