Transcriptome Analysis of Overexpressing NtH202 Nicotiana tabacum Leaves in Response to Tobacco Aphid Invasion

In order to screen the differentially expressed genes of Nicotiana tabacum under aphid stress, Nicotiana tabacum seedlings of wild type and overexpressed NtH202 strain were exposed to aphid, and the leaves were collected before and after 6 hours of exposure, total RNA was extracted, and transcriptome sequencing was performed. The differentially expressed genes were analyzed by GO and KEGG, the relevant transcription factors were mined, and verified by qRT-PCR. The results showed that there were 8 694 gene expression changes in WT and 6 795 gene expression changes in OE, and the number of up-regulated and down-regulated WT differential genes was higher, and 2 663 differential genes were changed by both. The GO classification showed that the number of genes enriched by OE into immune system process（GO:0002376） was significantly higher than that of WT. The plant-pathogen interaction pathway had the largest number of OE and WT differentially enriched genes, followed by plant hormone signal transduction, starch and sucrose metabolism pathway, and MAPK signal pathway-plant pathway. Compared with WT, a total of 1 342 genes of NtH202 overexpressed strain were upregulated more than 4 times. GO analysis showed that the functions of differentially expressed genes were mainly concentrated in biological processes, cell components and molecular functions. KEGG classification showed that compared with WT, OE was the most involved gene in plant pathogen interaction pathway before and after aphid invasion. After aphid invasion, 9 genes of WT and OE were up-regulated and 5 were down-regulated. RNA sequencing results of NtWRKY6, NtWRKY11, NtWRKY51, NtWRKY68 and NtWRKY70 genes were consistent with qRT-PCR results. It was predicted that WRKY transcription factor played an important role in anti-aphid response. After being invaded by aphids, 8 MYB genes were up-regulated and 8 MYB genes were down-regulated in both WT and OE genes. The results of RNA sequencing of MYB transcription factor ODO1 gene were consistent with the results of qRT-PCR, which predicted that transcription factor ODO1 played an important role in anti-aphid response of Nicotiana tabacum.