Publication Date:
2012-08-06
Description:
Background: Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum f. sp. cubense tropicalrace 4 (Foc TR4), is considered the most lethal disease of Cavendish bananas in the world.The disease can be managed in the field by planting resistant Cavendish plants generated bysomaclonal variation. However, little information is available on the genetic basis of plantresistance to Foc TR4. To a better understand the defense response of resistant banana plantsto the Fusarium wilt pathogen, the transcriptome profiles in roots of resistant and susceptibleCavendish banana challenged with Foc TR4 were compared. Results: RNA-seq analysis generated more than 103 million 90-bp clean pair end (PE) reads, whichwere assembled into 88,161 unigenes (mean size = 554 bp). Based on sequence similaritysearches, 61,706 (69.99%) genes were identified, among which 21,273 and 50,410 unigeneswere assigned to gene ontology (GO) categories and clusters of orthologous groups (COG),respectively. Searches in the Kyoto Encyclopedia of Genes and Genomes Pathway database(KEGG) mapped 33,243 (37.71%) unigenes to 119 KEGG pathways. A total of 5,008 geneswere assigned to plant-pathogen interactions, including disease defense and signaltransduction. Digital gene expression (DGE) analysis revealed large differences in thetranscriptome profiles of the Foc TR4-resistant somaclonal variant and its susceptible wildtype.Expression patterns of genes involved in pathogen-associated molecular pattern(PAMP) recognition, activation of effector-triggered immunity (ETI), ion influx, andbiosynthesis of hormones as well as pathogenesis-related (PR) genes, transcription factors,signaling/regulatory genes, cell wall modification genes and genes with other functions wereanalyzed and compared. The results indicated that basal defense mechanisms are involved inthe recognition of PAMPs, and that high levels of defense-related transcripts may contributeto Foc TR4 resistance in banana. Conclusions: This study generated a substantial amount of banana transcript sequences and compared thedefense responses against Foc TR4 between resistant and susceptible Cavendish bananas. Theresults contribute to the identification of candidate genes related to plant resistance in a nonmodelorganism, banana, and help to improve the current understanding of host-pathogeninteractions.
Electronic ISSN:
1471-2164
Topics:
Biology
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