Autor(es):
Santos, Carla S. 
; Pinheiro, Miguel ; Silva, Ana I, ; Egas, Conceição ; Vasconcelos, M. W.
Data: 2012
Identificador Persistente: http://hdl.handle.net/10400.14/9977
Origem: Veritati - Repositório Institucional da Universidade Católica Portuguesa
Descrição
Background: Pine wilt disease (PWD), caused by the pinewood nematode (PWN; Bursaphelenchus xylophilus),
damages and kills pine trees and is causing serious economic damage worldwide. Although the ecological
mechanism of infestation is well described, the plant’s molecular response to the pathogen is not well known. This
is due mainly to the lack of genomic information and the complexity of the disease. High throughput sequencing
is now an efficient approach for detecting the expression of genes in non-model organisms, thus providing
valuable information in spite of the lack of the genome sequence. In an attempt to unravel genes potentially
involved in the pine defense against the pathogen, we hereby report the high throughput comparative sequence
analysis of infested and non-infested stems of Pinus pinaster (very susceptible to PWN) and Pinus pinea (less
susceptible to PWN).
Results: Four cDNA libraries from infested and non-infested stems of P. pinaster and P. pinea were
sequenced in a full 454 GS FLX run, producing a total of 2,083,698 reads. The putative amino acid
sequences encoded by the assembled transcripts were annotated according to Gene Ontology, to assign
Pinus contigs into Biological Processes, Cellular Components and Molecular Functions categories. Most of the
annotated transcripts corresponded to Picea genes-25.4-39.7%, whereas a smaller percentage, matched Pinus
genes, 1.8-12.8%, probably a consequence of more public genomic information available for Picea than for
Pinus. The comparative transcriptome analysis showed that when P. pinaster was infested with PWN, the
genes malate dehydrogenase, ABA, water deficit stress related genes and PAR1 were highly expressed, while
in PWN-infested P. pinea, the highly expressed genes were ricin B-related lectin, and genes belonging to the
SNARE and high mobility group families. Quantitative PCR experiments confirmed the differential gene
expression between the two pine species.
Conclusions: Defense-related genes triggered by nematode infestation were detected in both P. pinaster and P. pinea
transcriptomes utilizing 454 pyrosequencing technology. P. pinaster showed higher abundance of genes related to
transcriptional regulation, terpenoid secondary metabolism (including some with nematicidal activity) and pathogen
attack. P. pinea showed higher abundance of genes related to oxidative stress and higher levels of expression in general
of stress responsive genes. This study provides essential information about the molecular defense mechanisms utilized
by P. pinaster and P. pinea against PWN infestation and contributes to a better understanding of PWD.
