Expression analysis of MAP2K9 and MAPK6 during pathogenesis of Alternaria blight in Arabidopsis thaliana ecotype Columbia

Abstract

Arabidopsis thaliana ecotype Columbia was used as a host in order to investigate the involvement of MAP kinase machinery in the pathogenesis of Alternaria blight. Semi-quantitative reverse transcriptase polymerase chain reaction and quantitative real time PCR based approaches were used to determine the change in transcript profile of MAP2K9 and MAPK6 in leaves of A. thaliana ecotpe Columbia at early, middle and late stages of Alternaria blight infection. It was observed that the expression of both MAP2K9 and MAPK6 simultaneously increased up to middle stage of disease progression. There was observed a positive correlation between the expression of MAPK6 and MAP2K9 as disease progressed from initial to middle stage of infection. Then, the expression of MAP2K9 decreased and that of MAPK6 increased as disease progressed towards late stage of infection. The increased levels of MAP2K9 and MAPK6, seem to be necessary for plant to defend the pathogen up to middle stage of infection. However, MAP2K9 may be down regulated at late stage of infection by pathogen to promote it's efficient colonization. Since MAPK6 expression remains unaltered till late stage, it suggests that it's expression is not only regulated by MAP2K9 but also by other MAP2K's. The above results are consistent with observations of earlier studies. In conclusion, the present study has suggested MAP2K9/MAPK6 module as possible target, which is influenced during pathogenesis of Alternaria blight in A. thaliana ecotype Columbia. Hence genetic modulation in expression levels of these components in Arabidopsis or Brassica could be a possible strategy for engineering defense against Alternaria blight disease.

Transcriptome analysis of Gossypium hirsutum flower buds infested by cotton boll weevil (Anthonomus grandis) larvae

“…For instance, two mitogen activated protein kinases (MAPK) that encode MAPK3 in A. thaliana were transcriptionally up-regulated (contig2100 and contig2102). Similarly, a member of the MAP Kinase Kinase family (MKK9, contig14909) and a protein kinase kinase kinase (MAPKKK14, contig7892) that play a role in leaf senescence during pathogenesis by Alternaria blight in A. thaliana were also transcriptionally up-regulated [ 28 ]. The activation of MAPK through wounding is dependent on the direct binding of calmodulins (CaM) in a Ca 2+ dependent manner.…”

Comparative transcriptome analysis of Gossypium hirsutumL. in response to sap sucking insects: aphid and whitefly

“…Thus, our results indicate the fine tuning of the JA pathway in cotton in response to the infestation by aphids and whiteflies. Further, in addition to changes in the expression of the genes involved in JA and ET biosynthesis, we also identified that the expression of hormonal signaling kinases, including MAP2K9 and MAPK6, was also altered, and the relation of MAP kinases in defense mechanisms involving JA, SA, and ET is well established [63]. We also identified that the expression of enzymes involved in oxidative radical scavenging were suppressed after the infestation by aphid and whiteflies (Table 4); these may lead to an increase in oxidative radicals and H 2 O 2 in the phloem sap, which is a probable strategy that is deployed by cotton plants against insect infestation [38].…”

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“…In Brassica crops, Alternaria brassicae incites Alternaria blight disease against which little information is available on the defense pathways. Fortunately Arabidopsis thaliana has been demonstrated as host for Alternaria brassicae (6), and the genes of MAPK signaling cascade in Arabidopsis thaliana are evolutionary conserved [6,7]. Therefore, in the present study, MAPK signaling cascade responsible for biosynthesis of camalexin in Brassica rapa has been elucidated using the genomic information from Arabidopsis.…”