Abstract
BackgroundRoot rot caused by Aphanomyces euteiches is one of the most destructive pea diseases while a distantly related species P. pisi has been recently described as the agent of pea and faba bean root rot. These two oomycete pathogens with different pathogenicity factor repertories have both evolved specific mechanisms to infect pea. However, little is known about the genes and mechanisms of defence against these pathogens in pea. In the present study, the transcriptomic response of pea to these two pathogens was investigated at two time points during early phase of infection using a Medicago truncatula microarray.ResultsOf the 37,976 genes analysed, 574 and 817 were differentially expressed in response to A. euteiches at 6 hpi and 20 hpi, respectively, while 544 and 611 genes were differentially regulated against P. pisi at 6 hpi and 20 hpi, respectively. Differentially expressed genes associated with plant immunity responses were involved in cell wall reinforcement, hormonal signalling and phenylpropanoid metabolism. Activation of cell wall modification, regulation of jasmonic acid biosynthesis and induction of ethylene signalling pathway were among the common transcriptional responses to both of these oomycetes. However, induction of chalcone synthesis and the auxin pathway were specific transcriptional changes against A. euteiches.ConclusionsOur results demonstrate a global view of differentially expressed pea genes during compatible interactions with P. pisi and A. euteiches at an early phase of infection. The results suggest that distinct signalling pathways are triggered in pea by these two pathogens that lead to common and specific immune mechanisms in response to these two oomycetes. The generated knowledge may eventually be used in breeding pea varieties with resistance against root rot disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1829-1) contains supplementary material, which is available to authorized users.
Highlights
Root rot caused by Aphanomyces euteiches is one of the most destructive pea diseases while a distantly related species P. pisi has been recently described as the agent of pea and faba bean root rot
Infection process evaluation The infection process of pea roots with A. euteiches and P. pisi was evaluated by analysing gene expression of selected defence marker genes such as Aminocyclopropane-carboxylate oxidase (ACO) (1-aminocyclopropane-1-carboxylate oxidase), Pi49 (PR10-like), ABA17 and chit4, using reverse transcription quantitative PCR (RT-qPCR)
The expression analyses of the pea OMT and M. truncatula Isoflavone 7-O-methyltransferase (I7OMT) gene illustrates these problems; Our microarray experiment showed that a gene similar to M. truncatula I7OMT was suppressed in response to A. euteiches at 20 hpi but the results obtained by RT-qPCR for a predicted pea O-methyltransferase (OMT) transcript with high similarity to M. truncatula I7OMT (75 % amino acid identity), obtained from a pea RNA-seq assembly [8], showed induction of this gene at 20 hpi
Summary
Root rot caused by Aphanomyces euteiches is one of the most destructive pea diseases while a distantly related species P. pisi has been recently described as the agent of pea and faba bean root rot. These two oomycete pathogens with different pathogenicity factor repertories have both evolved specific mechanisms to infect pea. Efficient chemical control of the pea root rot diseases caused by A. euteiches and P. pisi is not available and crop rotation and other cultural practices remain the only solutions to avoid the disease. The use of resistant pea varieties would be the most economical and ecological strategy to control the disease, no resistant variety to either pathogen is commercially available so far
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
