Abstract
BackgroundDiapause or developmental arrest, is one of the major adaptations that allows mites and insects to survive unfavorable conditions. Diapause evokes a number of physiological, morphological and molecular modifications. In general, diapause is characterized by a suppression of the metabolism, change in behavior, increased stress tolerance and often by the synthesis of cryoprotectants. At the molecular level, diapause is less studied but characterized by a complex and regulated change in gene-expression. The spider mite Tetranychus urticae is a serious polyphagous pest that exhibits a reproductive facultative diapause, which allows it to survive winter conditions. Diapausing mites turn deeply orange in color, stop feeding and do not lay eggs.ResultsWe investigated essential physiological processes in diapausing mites by studying genome-wide expression changes, using a custom built microarray. Analysis of this dataset showed that a remarkable number, 11% of the total number of predicted T. urticae genes, were differentially expressed. Gene Ontology analysis revealed that many metabolic pathways were affected in diapausing females. Genes related to digestion and detoxification, cryoprotection, carotenoid synthesis and the organization of the cytoskeleton were profoundly influenced by the state of diapause. Furthermore, we identified and analyzed an unique class of putative antifreeze proteins that were highly upregulated in diapausing females. We also further confirmed the involvement of horizontally transferred carotenoid synthesis genes in diapause and different color morphs of T. urticae.ConclusionsThis study offers the first in-depth analysis of genome-wide gene-expression patterns related to diapause in a member of the Chelicerata, and further adds to our understanding of the overall strategies of diapause in arthropods.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-14-815) contains supplementary material, which is available to authorized users.
Highlights
Diapause or developmental arrest, is one of the major adaptations that allows mites and insects to survive unfavorable conditions
We extend the knowledge on molecular mechanisms underlying diapause in arthropods to the spider mite T. urticae, a member of the Chelicerata that diverged more than 450 Mya from other arthropod lineages such as insects and crustaceans [33]
Analysis revealed that 1,994 genes (11% of all predicted genes) were differentially expressed (Figure 2), of which 1078 were downregulated and 916 were upregulated in diapausing females
Summary
Diapause or developmental arrest, is one of the major adaptations that allows mites and insects to survive unfavorable conditions. The spider mite Tetranychus urticae is a serious polyphagous pest that exhibits a reproductive facultative diapause, which allows it to survive winter conditions. Specific mechanisms have evolved to survive the extreme climatic conditions of winter One of those mechanisms is a developmental arrest, often considered as the most distinctive characteristic of diapause in insects and mites. In the two-spotted spider mite Tetranychus urticae, a hibernal facultative reproductive diapause allows adult female mites to survive winter [10]. Since this spider mite species is a highly polyphagous and difficult to control plant pest [11,12], winter survival has important consequences for crop protection in temperate climates. It was experimentally confirmed that T. urticae diapausing females show an increased cold hardiness, as the supercooling point of acclimated diapausing female mites is 6°C lower than non-diapausing females [27]
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