Transcriptome analyses suggest a novel hypothesis for whitefly adaptation to tobacco

Abstract

The adaptation of herbivorous insects to various host plants facilitates the spread and outbreak of many important invasive pests, however, the molecular mechanisms that underneath this process are poorly understood. In the past three decades, two species of the whitefly Bemisia tabaci complex, Middle East-Asia Minor 1 and Mediterranean, have invaded many countries. Their rapid and widespread invasions are partially due to their ability to infest a wide range of host plants. In this study, we determined the transcriptome and phenotypic changes of one Mediterranean whitefly population during its adaptation to tobacco, an unsuitable host plant. After several generations on tobacco, whiteflies showed increased survival and fecundity. High-throughput RNA sequencing showed that genes involved in muscle contraction and carbohydrate metabolism were significantly up-regulated after adaptation. Whiteflies reared on tobacco were further found to have increased body volume and muscle content and be trapped by tobacco trichomes in a lower frequency. On the other hand, gene expression in endosymbionts of whitefly did not change significantly after adaptation, which is consistent with the lack of cis-regulatory element on endosymbiont genomes. Over all, our data suggested that higher body volume and strengthened muscle might help whiteflies overcome physical barriers and survive on tobacco.

Host plant adaptation in the polyphagous whitefly, Trialeurodes vaporariorum, is associated with transcriptional plasticity and altered sensitivity to insecticides

“…These findings align with prior studies on M. persicae , Polygonia c-album and B. tabaci which all reported the upregulation of genes encoding cuticular proteins during host adaptation [9, 12, 52]. The specific role of cuticular proteins in insect host plant adaptation is unclear, however, a study of the adaptation of B. tabaci to tobacco observed both the upregulation of cuticular proteins and increases in body volume and muscle content [52]. Thus, the overexpression of cuticular proteins could play a role in host plant adaptation by mediating physical changes that allow insects to more readily survive the effects of feeding on hostile plants, and this in turn could impact their sensitivity to insecticides.…”

“…All proteins which were characterised belonged to the Rebers and Riddiford subgroup 2 (RR-2) cuticular family and so are associated with hard cuticle rather than flexible cuticle [51]. These findings align with prior studies on M. persicae , Polygonia c-album and B. tabaci which all reported the upregulation of genes encoding cuticular proteins during host adaptation [9, 12, 52]. The specific role of cuticular proteins in insect host plant adaptation is unclear, however, a study of the adaptation of B. tabaci to tobacco observed both the upregulation of cuticular proteins and increases in body volume and muscle content [52].…”

Genetic complexity of cassava brown streak disease: insights from qPCR-based viral titer analysis and genome-wide association studies

“…These diverse functions underscore the complexity of the identified GO and highlight their significance at the molecular and cellular levels during the initiation, establishment, and progression of viral infections. One GO of interest was cytoskeletal motor activity (GO:0003774), a function recognized for generating force essential for various movements ( Stewart et al., 2014 ; Houdusse, 2020 ), including muscle contraction in whiteflies’ adaptation to tobacco ( Xia et al., 2017 ). Cytoskeleton also participates in the regulation of host immune responses to infection by pathogens.…”

Is polyphagy of a specific cryptic Bemisia tabaci species driving the high whitefly populations on cassava in eastern Africa?

“…Bemisia tabaci is a group of cryptic species, whose members differ in their levels of polyphagy (Dinsdale et al, 2010;Mugerwa et al, 2018;Vyskočilová et al, 2019). B. tabaci MEAM1 and MED, for example, are highly polyphagous (Brown et al, 1995;Shah & Liu, 2013;Xia et al, 2017), whereas some species have a limited host range. Examples of monophagous species include the Jatropha race, which colonises Jatropha gossypifolia in Puerto Rico (Bird, 1957) and SSA6 that colonises Ocimum gratissimum in Uganda (Sseruwagi et al, 2005).…”