Abstract
Simple SummaryFusarium crown rot (FCR), caused by a soil-borne fungus Fusarium pseudograminearum, is one of the most destructive diseases of cereal crops, including wheat (Triticum aestivum) in many countries. It is vital to isolate resistance genes for improving crop resistance. Herein, we report the positive function of the wheat DUF26 domain-containing receptor-like kinase TaCRK-7A in the host resistance response to the pathogen F. pseudograminearum attack. The purified TaCRK-7A protein directly inhibited F. pseudograminearum mycelial growth. The TaCRK-7A transcript was elevated upon F. pseudograminearum infection and the transcript induction was higher in resistant wheat genotypes than in susceptible wheat genotypes. Knocking down of TaCRK-7A compromised resistance of wheat to FCR and significantly reduced the transcript levels of defense genes in wheat. This study provides a novel insight into the wheat immune responses to F. pseudograminearum. The fungus F. pseudograminearum can cause the destructive disease Fusarium crown rot (FCR) of wheat, an important staple crop. Functional roles of FCR resistance genes in wheat are largely unknown. In the current research, we characterized the antifungal activity and positive-regulatory function of the cysteine-rich repeat receptor-like kinase TaCRK-7A in the defense against F. pseudograminearum in wheat. Antifungal assays showed that the purified TaCRK-7A protein inhibited the growth of F. pseudograminearum. TaCRK-7A transcript abundance was elevated after F. pseudograminearum attack and was positively related to FCR-resistance levels of wheat cultivars. Intriguingly, knocking down of TaCRK-7A transcript increased susceptibility of wheat to FCR and decreased transcript levels of defense-marker genes in wheat. Furthermore, the transcript abundances of TaCRK-7A and its modulated-defense genes were responsive to exogenous jasmonate treatment. Taken together, these results suggest that TaCRK-7A can directly inhibit F. pseudograminearum growth and mediates FCR-resistance by promoting the expression of wheat defense genes in the jasmonate pathway. Thus, TaCRK-7A is a potential gene resource in FCR-resistant wheat breeding program.
Highlights
Fusarium crown rot (FCR) is a destructive disease of wheat (Triticum aestivum L.)and barley (Hordeum vulgare L.) worldwide [1]
We examined in vitro inhibition activity of the purified TaCRK7A protein against the growth of F. pseudograminearum and investigated its functional role in the wheat resistance to FCR caused by F. pseudograminearum infection
The deduced TaCRK-7A protein sequence includes an intracellular serine/threonine protein kinase domain, a transmembrane domain, and two DUF26 domains with the three conversed amino acids that are required for mannose binding activity and for antifungal activity [13]
Summary
Fusarium crown rot (FCR) is a destructive disease of wheat (Triticum aestivum L.). and barley (Hordeum vulgare L.) worldwide [1]. Functional roles of FCR resistance genes in wheat are largely unknown. In Arabidopsis and crop plants, several cysteine-rich repeat receptor-like protein kinases (CRKs) have been shown to confer resistance or be involved in the plant innate immune responses to bacterial and fungal pathogens [8,9,10,11,12]. No study about the functional roles of wheat CRK proteins in host resistance responses to F. pseudograminearum has been reported yet. In this current report, we examined in vitro inhibition activity of the purified TaCRK7A protein against the growth of F. pseudograminearum and investigated its functional role in the wheat resistance to FCR caused by F. pseudograminearum infection
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