Defense-related genes expressed in Norway spruce roots after infection with the root rot pathogen Ceratobasidium bicorne (anamorph: Rhizoctonia sp.).
To study the mechanisms of inducible disease resistance in conifers, changes in transcript accumulation in roots of Norway spruce (Picea abies (L.) Karst.) seedlings exposed to the root rot pathogen Ceratobasidium bicorne Erikss. and Ryv. (anamorph: Rhizoctonia sp.) were monitored by differential display (DD). Because C. bicorne attacks root tips, a desiccation treatment was added to exclude genes induced by pathogen-related desiccation stress. The DD analysis was defined by the use of 11 sets of primers, covering about 5% of the transcriptome. A comparison of gene expression in control, desiccation- and pathogen-stressed roots revealed 36 pathogen-induced gene transcripts. Based on database searches, these transcripts were assigned to four groups originating from spruce mRNA (25 transcripts), rRNA (five transcripts), fungal mRNA (two transcripts) and currently unknown cDNAs (four transcripts). Real-time PCR was applied to verify and quantify pathogen-induced changes in transcript accumulation. Of the 18 transcripts tested, nine were verified to be Norway spruce gene transcripts up-regulated from 1.3- to 66-fold in the infected roots. Four germin-like protein isoforms, a peroxidase and a glutathione S-transferase, all implicated in oxidative processes, including the oxidative burst, were predicted from sequence similarity searches. Seven class IV chitinase isoforms implicated in fungal cell wall degradation and a nucleotide binding site-leucine rich repeat (NBS-LRR) disease resistance protein homologue related to pathogen recognition were identified. Several transcript species, such as the NBS-LRR homologue and the germin-like protein homologues, have not previously been identified as pathogen-inducible genes in gymnosperms.
Jøhnk
Nina
N
Department of Plant Biology, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
Hietala
Ari M
AM
Fossdal
Carl G
CG
Collinge
David B
DB
Newman
Mari-Anne
MA
D000595:Amino Acid Sequence; D002688:Chitinases / Q000235:genetics; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D005982:Glutathione Transferase / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics; D009195:Peroxidase / Q000235:genetics; D028222:Picea / Q000201:enzymology / Q000235:genetics* / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology*; D020033:Protein Isoforms; D012232:Rhizoctonia / Q000502:physiology*; D015398:Signal Transduction; D014867:Water
D006023:Glycoproteins; D020033:Protein Isoforms; D014867:Water; D009195:Peroxidase; D005982:Glutathione Transferase; D002688:Chitinases