Abstract
The domain of unknown function 26 (DUF26), harboring a conserved cysteine-rich motif (C-X8-C-X2-C), is unique to land plants. Several cysteine-rich repeat proteins (CRRs), belonging to DUF26-containing proteins, have been implicated in the defense against fungal pathogens in ginkgo, cotton, and maize. However, little is known about the functional roles of CRRs in the important staple crop wheat (Triticum aestivum). In this study, we identified a wheat CRR-encoding gene TaCRR1 through transcriptomic analysis, and dissected the defense role of TaCRR1 against the soil-borne fungi Rhizoctonia cerealis and Bipolaris sorokiniana, causal pathogens of destructive wheat diseases. TaCRR1 transcription was up-regulated in wheat towards B. Sorokiniana or R. cerealis infection. The deduced TaCRR1 protein contained a signal peptide and two DUF26 domains. Heterologously-expressed TaCRR1 protein markedly inhibited the mycelia growth of B. sorokiniana and R. cerealis. Furthermore, the silencing of TaCRR1 both impaired host resistance to B. sorokiniana and R. cerealis and repressed the expression of several pathogenesis-related genes in wheat. These results suggest that the TaCRR1 positively participated in wheat defense against both B. sorokiniana and R. cerealis through its antifungal activity and modulating expression of pathogenesis-related genes. Thus, TaCRR1 is a candidate gene for improving wheat resistance to B. sorokiniana and R. cerealis.
Highlights
Common wheat (Triticum aestivum) is one of the most widely cultivated and important staple crops in the world [1]
To explore if domain of unknown function 26 (DUF26)-containing cysteine-rich repeat proteins (CRRs) are involved in wheat resistance responses to the soil-borne pathogens—R. cerealis and B. sorokiniana, we identified a wheat CRR-encoding gene TaCRR1 in wheat defense responses to R. cerealis and B. sorokiniana, and validated the defense function of TaCRR1
These results extend our understanding of wheat resistance mechanisms against the sharp eyespot caused by R. cerealis and common root rot caused by B. sorokiniana
Summary
Common wheat (Triticum aestivum) is one of the most widely cultivated and important staple crops in the world [1]. To combat numerous biotic stresses, plants have evolved two-layers of immune systems including pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) [8] Both responses lead to the production of defense molecules and pathogenesis-related (PR) proteins [8,9]. Further functional investigation indicated that the knocking-down of TaCRR1 by virus-induced gene-silencing (VIGS) impaired host resistance to B. sorokiniana and R. cerealis and repressed expression of pathogenesis-related genes in wheat, including β-1,3-Glucanase, Defensin, Chitinase, Chitinase, and Chitinase. Further functional investigation indicated that the knocking-down of TaCRR1 by virus-induced gene-silencing (VIGS) impaired host resistance to B. sorokiniana and R. cerealis and repressed expression of pathogenesis-related genes in wheat, including β-1,3-Glucanase, Defensin, Chitinase, Chitinase, and Chitinase4 These results extend our understanding of wheat resistance mechanisms against the sharp eyespot caused by R. cerealis and common root rot caused by B. sorokiniana. The expression profiles of TaCRR1 indicated that the gene might be involved in wheat resistance responses to infection of R. cerealis and B. sorokiniana
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