Lilium regale Wilson WRKY3 modulates an antimicrobial peptide gene, LrDef1, during response to Fusarium oxysporum

Abstract

Background WRKY transcription factors (TFs) play vital roles in plant growth and development, secondary metabolite synthesis, and response to biotic and abiotic stresses. In a previous transcriptome sequencing analysis of Lilium regale Wilson, we identified multiple WRKY TFs that respond to exogenous methyl jasmonate treatment and lily Fusarium wilt (Fusarium oxysporum). Results In the present study, the WRKY TF LrWRKY3 was further analyzed to reveal its function in defense response to F. oxysporum. The LrWRKY3 protein was localized in the plant cell nucleus, and LrWRKY3 transgenic tobacco lines showed higher resistance to F. oxysporum compared with wild-type (WT) tobacco. In addition, some genes related to jasmonic acid (JA) biosynthesis, salicylic acid (SA) signal transduction, and disease resistance had higher transcriptional levels in the LrWRKY3 transgenic tobacco lines than in the WT. On the contrary, L. regale scales transiently expressing LrWRKY3 RNA interference fragments showed higher sensitivity to F. oxysporum infection. Moreover, a F. oxysporum-induced defensin gene, Def1, was isolated from L. regale, and the recombinant protein LrDef1 isolated and purified from Escherichia coli possessed antifungal activity to several phytopathogens, including F. oxysporum. Furthermore, co-expression of LrWRKY3 and the LrDef1 promoter in tobacco enhanced the LrDef1 promoter-driven expression activity. Conclusions These results clearly indicate that LrWRKY3 is an important positive regulator in response to F. oxysporum infection, and one of its targets is the antimicrobial peptide gene LrDef1.

Pepper immunity against Ralstonia solanacearum is positively regulated by CaWRKY3 through modulation of different WRKY transcription factors

“…The members of this family have been demonstrated to play important roles in the control of plant immunity in Arabidopsis and rice. Previous research has shown that WRKY proteins found in a wide range of plant species have high degrees of structural similarity but vastly different functional properties [ 33 , 34 ]. However, the function of WRKY TFs in immunological responses of non-model plants, such as pepper, has received less attention.…”

“…This data suggested that CaWRKY3 positively regulate pepper plant immunity and play a critical part in the defense of plants against bacterial pathogen. Previous studies exhibited that WRKY3 is a positive regulator of plant defense against F. oxysporum in Lilium regale and transcriptional levels of JA-biosynthesis, SA-signal transduction-related marker genes were up-regulated in LrWRKY3 transgenic tobacco lines [ 33 , 34 ]. It can be suggested that CaWRKY3 is up-regulated upon inoculation of R. solanacearum .…”

Overexpression of CmWRKY8-1–VP64 Fusion Protein Reduces Resistance in Response to Fusarium oxysporum by Modulating the Salicylic Acid Signaling Pathway in Chrysanthemum morifolium

“…Currently, an increasing number of studies on WRKY responses to F. oxysporum infestation are also being conducted. LrWRKY3 heterologously specializes in tobacco, which exhibits enhanced resistance to F. oxysporum infestation, and transient expression of the LrWRKY3 RNAi vector in Lilium regale scales increased the susceptibility to F. oxysporum [ 33 ]. In cotton, group IIc WRKY TFs enhance resistance to F. oxysporum by promoting flavonoid synthesis via the WRKY-MAPK pathway [ 34 ].…”