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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #174585
Title: INDUCTION OF WHEAT DEFENSE AND STRESS-RELATED GENES IN RESPONSE TO FUSARIUM GRAMINEARUM

Author
item KONG, LINGRANG - PURDUE UNIVERSITY
item Anderson, Joseph
item OHM, HERBERT - PURDUE UNIVERSITY

Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2005
Publication Date: 2/11/2005
Citation: Kong, L., Anderson, J.M., Ohm, H. 2005. Induction of wheat defense and stress-related genes in response to fusarium graminearum. Genome. 48:29-40.

Interpretive Summary: Fusarium head blight (FHB) caused by the fugal pathogen Fusarium graminearum poses a serious threat to wheat production worldwide, lowers grain yield, and reduces grain quality due to the production of a mycotoxin. Breeding wheat resistant to FHB is one of the best options to minimize these crop and grain quality losses. Wheat responds to F. graminearum infection by inducing various defense responses such as increasing the thickness of cell walls to potentially impede further growth of the fungus and inducing the activity of a number of stress response genes. However, the relationship between these stress response genes and resistance to FHB has not been established. In this study, wheat genes whose pattern of expression changed after infection by Fusarium graminearum were identified, isolated and characterized. The induction of three genes (P450, chitinase, and one gene of unknown function) in the resistant genotypes compared with susceptible genotypes indicates a possible role in the resistance response to F. graminearum. Identifying and characterizing these types of wheat host genes will help determine cellular processes that are activated or repressed during the early phase of host-pathogen interactions that ultimately determine the extent of fungal colonization and will identify genes that may provide Plant Pathologists and other scientists durable and effective resistance to FHB.

Technical Abstract: Fusarium Head Blight (FHB), caused by the fungus Fusarium species, is a worldwide disease of wheat (Triticum aestivum L.). The Chinese cultivar, Ning7840, is one of only a few wheat cultivars with resistance to FHB. To identify differentially expressed genes corresponding to FHB resistance, a cDNA library was constructed from pooled mRNA isolated from glumes of Ning7840 harvested at 2, 6, 12, 24, 36, 72 and 96 hours after inoculation (hai) with a spore suspension of Fusarium graminearum. Suppressive subtractive hybridization (SSH) cDNA subtraction was carried out using pooled glume mRNAs from the tester and the control. The cDNA library was differentially screened using the forward subtracted cDNAs and the reverse subtracted cDNAs as probes. Twenty four clones with significant matches to either plant genes (16 sequences) or fungal genes (8 sequences) were isolated based on their specific hybridization with forward subtracted cDNA and not reverse subtracted cDNA. Six putative defense-related genes were confirmed by quantitative real-time PCR. Many-fold higher induction of three genes (A3F8, B10H1, and B11H3) in the resistant genotypes compared with susceptible genotypes indicates a putative role in the resistance response to F. graminearum. Accumulation of three other gene transcripts, P450, chitinase, and an unknown gene (B8Q9), in both resistant and susceptible genotypes suggest an involvement in a generalized resistance response to F. graminearum. Nucleotide sequence analysis showed that cDNA clone A4C6 encodes a cytochrome P450 genes (CYP709C3v2), including 16 N-terminal amino acids that have a membrane-associated helical motif. Other domains characteristic of eukaryotic P450 are also present in CYP709C3v2. The deduced polypeptide of cDNA clone B2H2 encodes an acidic isoform of class I chitinase containing a 960 bp coding region. Southern hybridization with aneuploid lines of Chinese Spring wheat indicated that CYP709C3v2 was located on the short arm of chromosomes 2B and 2D.