Changes in Gene Expression of Whiteflies, Bemisia tabaci MED Feeding on Tomato Plants Infected by One of the Criniviruses, Tomato Chlorosis Virus through Transcriptome Analysis

Abstract

Tomato chlorosis virus (ToCV), transmitted by the whitefly, Bemisia tabaci (Gennadius; Hemiptera: Aleyrodidae) has been continuously emerging on tomato plants and causing a significant economic loss throughout China. In the current study, RNA-Seq analysis was used to explore the gene expression profiles of B. tabaci Mediterranean (MED) that fed on both ToCV-infected and -uninfected tomato plants for 6, 12, 24, and 48 hours, respectively. The results revealed that dynamic changes occurred in the gene expressions of whiteflies at different time intervals after they acquired the virus. A total of 1709, 461, 4548, and 1748 differentially expressed genes (DEGs) were identified after a 6, 12, 24, and 48 hours feeding interval for the viral acquisition, respectively. The least number of expressed genes appeared in whiteflies with the 12 hours feeding treatment, and the largest numbers of those found in those with 24 hours feeding treatment. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that B. tabaci MED responded to ToCV acquisition through altering its nerve system development, fertility, detoxification, glucose metabolism, and immune function before it lost its ability to transmit the virus. The number of DEGs, degree of differential gene expressions, expression level of the same gene, involved biological processes, and metabolic functions in whiteflies post the 12 hours feeding, and viral acquisition were different from those from other three feeding treatments, which could be a significant finding suggesting an effective control of B. tabaci MED should be done less than 12 hours after whiteflies started feeding on ToCV-infected tomatoes. Our results further provided a clarified understanding in how B. tabaci was protected from viral acquisitions through comparison of the differential profile of gene expressions in whiteflies feeding on plants that were infected by semipersistent viruses.

Figure 1

Volcano plots of DEGs in B. tabaci MED at 6, 12, 24, and 48 hours after feeding on ToCV-infected and healthy tomato plants. “T” stands for the poisoned tomato group (treatment group). “H” stands for the healthy tomato group. Different numbers after the letters represent the FI of B. tabaci. Red points represent significantly up-regulated genes, green points represent significantly down-regulated genes, and blue points represent non-DEGs. The abscissa represents gene expression fold change in different samples. Ordinate represents the statistical significance of the difference in gene expression.

Figure 2

Common and special DEGs in B. tabaci MED at 6, 12, 24, and 48 hours. Different colors represent different comparison combinations. The sum of the numbers in each large circle represents the total number of differential genes in the comparison combination, and the overlapping parts of the circles represent the common differential genes among the combinations.

Figure 3

GO enrichment analysis of 6 hours. The x-coordinate represents the GO term, and the y-coordinate represents the number of genes. Red represents up-regulated genes, and green represents down-regulated genes.

Figure 4

GO enrichment analysis of 12 hours. The x-coordinate represents the GO term, and the y-coordinate represents the number of genes. Red represents up-regulated genes, and green represents down-regulated genes.

Figure 5

GO enrichment analysis of 24 hours. The x-coordinate represents the GO term, and the y-coordinate represents the number of genes. Red represents up-regulated genes, and green represents down-regulated genes.

Figure 6

GO enrichment analysis of 48 hours. The x-coordinate represents the GO term, and the y-coordinate represents the number of genes. Red represents up-regulated genes, and green represents down-regulated genes.

Figure 7

Enriched KEGG pathway scatterplots of up-regulated (left) and down-regulated genes (right) in B. tabaci MED at 6, 12, 24, and 48 hours feeding on ToCV-infected tomato. The ordinate represents the name of pathway. The abscissa represents a rich factor. The size of dots indicates the number of DEGs, whereas the color of dots corresponds to different q-value ranges.

Figure 8

Verification of DEGs by RT-qPCR. The expression levels of eight selected genes were measured by RT-qPCR using the 2^−ΔΔCT method. Values are means ± SE. The different letters indicate significant differences between treatments (p < 0.05) detected by one - way ANOVA/Duncan's multiple range test.