Transcriptomic and metabolomic profiles of Chinese citrus fly, Bactrocera minax (Diptera: Tephritidae), along with pupal development provide insight into diapause program.

Jia Wang,Ying-Hong Liu,Ke-Cai Xiong,Huan Fan,J Joe Hull

doi:10.1371/journal.pone.0181033

Abstract

The Chinese citrus fly, Bactrocera minax (Enderlein), is a devastating citrus pest in Asia. This univoltine insect enters obligatory pupal diapause in each generation, while little is known about the course and the molecular mechanisms of diapause. In this study, the course of diapause was determined by measuring the respiratory rate throughout the pupal stage. In addition, the variation of transcriptomic and metabolomic profiles of pupae at five developmental stages (pre-, early-, middle-, late-, and post-diapause) were evaluated by next-generation sequencing technology and 1H nuclear magnetic resonance spectroscopy (NMR), respectively. A total of 4,808 genes were significantly altered in ten pairwise comparisons, representing major shifts in metabolism and signal transduction as well as endocrine system and digestive system. Gene expression profiles were validated by qRT-PCR analysis. In addition, 48 metabolites were identified and quantified by 1H NMR. Nine of which significantly contributed to the variation in the metabolomic profiles, especially proline and trehalose. Moreover, the samples collected within diapause maintenance (early-, middle-, and late-diapause) only exhibited marginal transcriptomic and metabolomic variation with each other. These findings greatly improve our understanding of B. minax diapause and lay the foundation for further pertinent studies.

Highlights

The Chinese citrus fly, Bactrocera minax (Enderlein), is a devastating oligophagous pest of citrus plants in the temperate areas of Asia, especially in China [1,2,3]
The model describing the respiratory rate trajectory was fitted well according to Chi-square test (χ2 = 0.0824, d.f. = 44, P > 0.05)
Two months after initiation, diapause terminated and pupal development resumed with the respiratory rate increasing by 39-fold

Summary

Introduction

The Chinese citrus fly, Bactrocera minax (Enderlein), is a devastating oligophagous pest of citrus plants in the temperate areas of Asia, especially in China [1,2,3]. Larval feeding can cause serious yield losses [4,5,6], as such this pest has become a focus of interest in citrus-growing regions in China. The long-lasting pupal stage in which diapause occurs has severely hindered the laboratory-rearing of this pest and restricted further scientific research. Diapause is a life history stage that allows insects to mitigate acute environmental stresses [14,15].

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Discussion

Conclusion