GM Bt rice may negatively impact beneficial predator spider

A new study shows that GM Bt rice may negatively impact the development of a beneficial predator spider which plays a crucial role in the rice agroecosystem.

A comparative transcriptome (gene function) analysis revealed 136 differentially expressed genes between spiderlings preying upon N. lugens (the brown planthopper pest) that were fed on Bt- and non-Bt rice.

Some of the differentially expressed genes in the spiderlings maintained on the GM-fed planthoppers were associated with the formation of new cuticles – the “shell” that the spider sheds during moulting. Moulting enables the spider to grow and develop.

The researchers recommend that further research is done to see if the transcriptome changes translate into changes in proteins that in turn lead to actual delays in development.

Article Information:

Transcriptomic response of wolf spider, Pardosa pseudoannulata, to transgenic rice expressing Bacillus thuringiensis Cry1Ab protein
BMC Biotechnology 2017 17:7
Published: 18 January 2017
DOI: 10.1186/s12896-016-0325-2
Open access: http://bit.ly/2jDaVBd

Background
Bacillum thuringiensis (Bt) toxin produced in Cry1-expressing genetically modified rice (Bt rice) is highly effective to control lepidopteran pests, which reduces the needs for synthetic insecticides. Non-target organisms can be exposed to Bt toxins through direct feeding or trophic interactions in the field. The wolf spider Pardosa pseudoannulata, one of the dominant predators in South China, plays a crucial role in the rice agroecosystem. In this study, we investigated transcriptome responses of the 5th instar spiders fed on preys maintained on Bt- and non-Bt rice.

Results
Comparative transcriptome analysis resulted in 136 differentially expressed genes (DEGs) between spiderlings preying upon N. lugens fed on Bt- and non-Bt rice (Bt- and non-Bt spiderlings). Functional analysis indicated a potential impact of Bt toxin on the formation of new cuticles during molting. GO and KEGG enrichment analyses suggested that GO terms associated with chitin or cuticle, including “chitin binding”, “chitin metabolic process”, “chitin synthase activity”, “cuticle chitin biosynthetic process”, “cuticle hydrocarbon biosynthetic process”, and “structural constituent of cuticle”, and an array of amino acid metabolic pathways, including “alanine, asparatate and glutamate metabolism”, “glycine, serine and theronine metabolism”, “cysteine and methionine metabolism”, “tyrosine metabolism”, “phenylalanine metabolism and phenylalanine”, and “tyrosine and tryptophan biosynthesis” were significantly influenced in response to Cry1Ab.

Conclusions
The Cry1Ab may have a negative impact on the formation of new cuticles during molting, which is contributed to the delayed development of spiderlings. To validate these transcriptomic responses, further examination at the translational level will be warranted.