Characterization and Comparative Profiling of miRNAs in Invasive Bemisia tabaci (Gennadius) B and Q

Abstract

BackgroundMicroRNAs (miRNAs) are small, conserved, non-coding RNAs that post-transcriptionally regulate gene expression. Bemisia tabaci (Gennadius) B and Q are two invasive and dominant whiteflies, and B. tabaci Q has been displacing B in China. Differences in biological traits (fecundity, host range, resistance to insecticides, etc.) as affected by miRNAs might be involved in the displacement. In this study, we performed high-throughput sequencing to identify miRNAs in B. tabaci B and Q.ResultsWe identified 170 conserved miRNAs and 15 novel candidates, and found significant differences in the expression of miRNAs between B. tabaci B and Q.ConclusionExpression levels of miRNAs differ in B. tabaci B vs. Q. Additional research is needed to determine whether these differences are related to differences in the biology of B. tabaci B and Q, and whether these differences help explain why B. tabaci Q is displacing B in China.

Small RNAs from Bemisia tabaci Are Transferred to Solanum lycopersicum Phloem during Feeding

“…These longer sRNAs were indeed also observed in the whitefly nymphs (Figure 2). A similar sRNA length distribution has previously been found in adult whiteflies (Guo et al, 2013; Wang et al, 2016) and similar sized sRNAs (between 26 and 30 nts) have been reported for other insects e.g., cotton-melon aphid ( Aphis gossypii ) or the brown planthopper ( Nilaparvata lugens ; Chen et al, 2012; Sattar et al, 2012). These longer sRNAs are assumed to be Piwi-interacting RNAs (piRNAs) and are known to be a large class of non-coding RNAs in animals, specifically linked to genome stability in germ-line cells and silence transposons (Vagin et al, 2006).…”

“…LC, control leaflets (not infested with whitefly nymphs); LW, leaflets first infested with whiteflies but with adults and nymphs subsequently removed; LE, leaflets with whitefly eggs; WN, whitefly nymphs; PC, phloem control (not infested); PW, phloem infested with whitefly nymphs. Insets for LW, WN, and PW represent the size distributions and percentages of the sRNAs matching previously described whitefly miRNAs (Guo et al, 2013). …”

“…Next, the sRNAs from whitefly-infested samples LW, WN, and PW were compared to 185 whitefly miRNA sequences found in two different biotypes of B. tabaci (Guo et al, 2013). All previously described whitefly miRNAs had a length comprised between 20 and 24 nts (Guo et al, 2013).…”

“…All previously described whitefly miRNAs had a length comprised between 20 and 24 nts (Guo et al, 2013). Accordingly, 150 sRNAs of our WN sample could be exactly matched to the whitefly miRNAs published earlier (Table S3) and had a length predominantly centered around 22 nts, a feature characteristic of insect miRNAs (Figure 2, insets).…”

“…Figure 3A shows that sRNA #29691 was indeed specific to the nymph sample and was absent in the LW, LC, or LE samples, indicating that there is no whitefly nymph contamination in the LW sample after the infestation and that nymphs had been successfully removed. Sample quality was further checked using a known B. tabaci specific sRNA (Bta_miR2A; Guo et al, 2013) and a known tomato miR172 that is conserved among land plants (Taylor et al, 2014). Accordingly, the plant-specific miR172 was detected in all leaf samples (Figure 3B) while the whitefly Bta_miR2A was detected in the nymph samples of B. tabaci reared on tomato and in the leaf samples containing eggs (LW and LE; Figure 3C).…”