Insect herbivores often secrete glucose oxidase (GOX) onto
plants to counteract plant defenses and potential pathogens. Whether generalist
herbivores always have significantly higher GOX activities than their specialist
counterparts at any comparable stage or conditions and how this is realized remain
unknown. To address these two general questions, we subjected larvae of a pair of sister
species differed mainly in host range, the generalist Helicoverpa armigera and its
specialist counterpart Helicoverpa assulta, to the same sets of stage, protein to
digestible carbohydrate (P:C) ratio, allelochemical or host plant treatments for
simultaneous analyses of GOX transcripts and activities in their labial glands. GOX
activity and transcripts are upregulated concurrently with food ingestion and body
growth, downregulated with stopping ingestion and wandering for pupation in both
species. The three tested host plants upregulated GOX transcripts, and to a lesser extent,
GOX activity in both species. There were significant differences in both GOX
transcripts and activity elicited by allelochemicals, but only in GOX transcripts by P:C
ratios in both species. GOX activities were higher in H. armigera than H. assulta in all
the comparable treatments, but GOX transcripts were significantly higher either in
generalists or in specialists, depending on the developmental stages, host plants, P:C
ratio and allelochemicals they encounter. These data indicate that the greater GOX
activity in generalist herbivores is not achieved by greater transcription rate, but by
greater transcript stability, greater translation rate, better enzyme stability and/or their
combination.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/625992 |
| Date | 07 1900 |
| Creators | Yang, Lihong, Wang, Xiongya, Bai, Sufen, Li, Xin, Gu, Shaohua, Wang, Chen-Zhu, Li, Xianchun |
| Contributors | Univ Arizona, Dept Entomol |
| Publisher | Elsevier |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017 Elsevier Ltd. All rights reserved. |
| Relation | http://linkinghub.elsevier.com/retrieve/pii/S0022191016304450 |
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