ObjectiveTo develop a new inducer of enhancing plant immunity, the function of the eliciting plant response protein Epl1 to the woody plant Populus davidiana × P. alba var. pyramidlis (PdPap) was studied.

MethodAn eliciting plant response protein gene Epl1 was cloned and analyzed from Trichoderma asperellum ACCC30536. The recombinant protein rEpl1 was obtained by prokaryotic expression, and the effect of rEpl1 was discussed on the growth, physical signs, and the transcription level of gene related to growth and defence of PdPap during the interaction between rEpl1 and PdPap tissue culture seedlings.

ResultThe results showed that the cDAN sequence of the gene Epl1 was 417 bp long with a predicted protein of 12.6 kDa molecular weight, which belonged to the cerato-platanin family. The prokaryotic expression plasmid was constructed and the recombinant protein rEpl1 was successfully expressed. Under 1 μg/mL rEpl1 induction, the PdPap seedlings had an fast growth, developed root and the increasing biomass; the CAT activity of PdPap seedlings was 3.51 folds of the control at 1st day, and the soluble sugar content and proline content of PdPap seedlings were sharply accumulated; the transcription levels of auxin gene (LAX2/AUX) and defence gene (JAR2) of PdPap seedlings reached the peak at 2nd day and 12 hours, and the peak was 873.10 and 388.02 folds of the control, respectively.

ConclusionSo, the cloning, sequence analysis and prokaryotic expression of the gene Epl1 provided fundamental basis for studying Epl1 protein eliciting plant systemic resistance; through the interaction between the recombinant protein rEpl1 and PdPap seedlings, it was confirmed that Epl1 protein could stimulate the response of the wood plant on the level of physiology and molecular, which could promote plant growing and improve plant resistance.