The Effect Of Transformed HPA1_10-42 On Resistance To English Grain Aphid And Screening Of Related MYB Genes In Wheat

Harpins produced by Gram-negative phytopathogenic bacteria have been shown to activate plant defense pathways, induce plant resistance to pathogens and insect pests and promote plant growth. Here we chose the Hpal protein, focusing on analysis of the transgenic expression of Hpal 10-42 in wheat induces resistance to English grain aphid. Transcription factors play vital roles in plant growth and development processes in response to a variety of biological and non-biological stresses. In this study, we investigated 10 MYB genes involved in the interactions between transgenic wheat and aphids. Also, we develop a system of virus induced gene silencing, which lay foundations for further study the function of the transcription fetors.1. The effect of transformed Hpal 10-42 on resistance to English grain aphid in wheatThe harpin protein Hpal produced by the rice bacterial blight pathogen promotes plant growth and induces plant resistance to pathogens and insect pests. The region of 10-42 residues (Hpal 10-42) in the Hpal sequence is critical as the isolated Hpal 10-42 fragment is 1.3-7.5-fold more effective than the full length in inducing plant growth and resistance. Here we report that transgenic expression of Hpal 10-42 in wheat induces resistance to English grain aphid, a dominant species of wheat aphids. Hpal10-42-induced resistance is effective to inhibit the aphid behavior in plant preference at the initial colonization stage and repress aphid performances in the reproduction, nymph growth, and instar development on transgenic plants. The resistance characters are correlated with enhanced expression of defense-regulatory genes (EIN2, PP2-A, and GLS10) and consistent with induced expression of defense response genes (Hel, PDF 1.2, PR-1b, and PR-2b). As a result, aphid infestations are alleviated in transgenic plants. The level of Hpal 10-42-induced resistance in regard to repression of aphid infestations is equivalent to the effect of chemical control provided by an insecticide. These results suggest that the defensive role of Hpal 10-42 can be integrated into breeding germplasm of the agriculturally significant crop with a great potential of the agricultural application.2. Screening of MYB genes involved in Hpal 10-induced resistance to aphids in wheatTranscription factors response to hormone stimulation and the external environment stress, regulate gene expression level and even control the spatial and temporal specificity of gene expression. There are 7 important TF families in plants and the MYB superfamily has been defined as the most abundant TF family, different members of this family play vital roles in developmental processes and defence responses in plants. The purpose of this study is to screen MYB genes which participate in the interactions between transgenic wheat and aphids. In order to further verify the function of these MYB genes, we developed a system of virus induced gene silencing (VIGS) by barley stripe Mosaic virus (BSMV) in wheat seedlings. Here we investigated 60 MYB transcription factors in the interactions between transgenic wheat and aphids. Compared with wild-type Y16,10 MYB genes increased significantly in transcription level in Y16:Hpal 10-42 lines. The system of BSMV induced endogenous MYB gene silencing in wheat seedlings has been developed in the present study. The efficient system of the endogenous genes silencing induced by BSMV in wheat leaves will provide a fast and effective method for functional identification of MYB genes in wheat resistance to aphids.