Variability in herbivore-induced defence signalling across different maize genotypes impacts significantly on natural enemy foraging behaviour

‘Smart’ plants that release volatile defence compounds in response to pest damage, and which recruit beneficial natural enemies, offer an opportunity for exploiting biological control in future crop protection strategies. Using six maize genotypes, Zapalote Chico (‘landrace’), Mirt2A, Sintético Spodoptera (SS), L3, and two commercial hybrids BRS 4103 and BRS 1040, the aim of this work was to evaluate maize responses to larval damage from the fall armyworm Spodoptera frugiperda, a major maize pest in Brazil, and the ability of the egg parasitoid Telenomus remus to respond to HIPVs induced by S. frugiperda damage. Y-tube olfactometer bioassays with T. remus showed preferential responses to the S. frugiperda-induced volatiles of SS and BRS 4103 compared to constitutive volatiles of the same genotypes, but to none of the other genotypes tested. Chemical analysis of maize volatile extracts showed that SS produced more volatile compounds in response to S. frugiperda damage, followed by BRS 4103. In addition, higher levels of mono, homo-, or sesquiterpenes, together with green leaf volatiles (GLVs) were the most attractive blend for T. remus; however, there was no attraction when only GLVs were produced in higher levels. In summary, these results show that volatile defence signalling produced by maize plants due to S. frugiperda damage varies significantly depending on maize genotype and this variability influences T. remus foraging behaviour

Transcriptome-Based Identification of Highly Similar Odorant-Binding Proteins among Neotropical Stink Bugs and Their Egg Parasitoid - Fig 6

<p>Alignment of the deduced amino acid sequences of OBPs from the parasitoid <i>T</i>. <i>podisi</i> and the most similar OBPs obtained from GenBank by BLASTx: (a) TpodOBP1; (b) TpodOBP2; (c) TpodOBP3. Similarity is scored by matrix Blosum62 where the black color indicates 100% identity, darker grey 100% > identity ≥ 80%, lighter grey 80% > identity ≥ 60% and white color identity <60%. The sequence logo is at the top of the alignment. The amino acid percentage identity matrix is presented in Table H in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>. The conserved Cys are indicated by sequence logo. The species names are abbreviated with four letters, and their full names with all accession numbers of the OBP amino acid sequences are provided in Table I in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>.</p

Phylogenetic relationships of: (a) target stink bug putative OBPs (in red) and putative 185 other hemipteran OBPs; (b) Detailed relationships of the putative EherOBPs, CubiOBPs, and DimelOBP.

<p>The trees were constructed with MEGA 6.06 using a LG+G+I model. Values indicated at the nodes are bootstrap values based on 1,000 replicates presented with 50% cut-off bootstrap value for (a) and no cut-off for (b). The species names are abbreviated with four letters, and their full names with all accession numbers of the OBP amino acid sequences are provided in Table I in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>.</p

Alignment of the predicted tertiary structures of the full-length putative OBPs from the stink bugs <i>E</i>. <i>heros</i>, <i>C</i>. <i>ubica</i> and <i>D</i>. <i>melacanthus</i> and from the parasitoid <i>T</i>. <i>podisi</i>.

<p>Blue shows structural similarities and red shows dissimilarities according to the matrix Blosum60 for: (a) within EherOBPs; (b) within CubiOBPs; (c) between EherOBP3 and CubiOBP3; (d) between EherOBP6 and CubiOBP1; (e) within TpodOBPs; (f) between TpodOBP1 and EherOBP2; (g) between TpodOBP2 and EherOBP1. The structures were generated by I-TASSER server 4.2 and were oriented with the N-terminal to the right side.</p

Match species, rank of the highest normalized number of hits for the target stink bugs and parasitoid, Kruskal-Wallis H value (H) and type I error probability (P).

<p>Match species in bold are significantly different among the target stink bugs and parasitoid.</p

Most frequent biological processes (a) and molecular functions (b) categories from the antennae of 12 day-old virgin adults of stink bugs and whole body of 20 day-old parasitoid.

<p>The number of transcripts for a particular GO term (at lower hierarchy level) in each category was normalized by the total number of classified transcripts.</p

Physico-chemical predictions for the putative full-length OBPs obtained from the target stink bugs (<i>E</i>. <i>heros</i>, <i>C</i>. <i>ubica</i> and <i>D</i>. <i>melacanthus</i>) and parasitoid (<i>T</i>. <i>podisi</i>).

<p>AA: Amino acid residue number; pI: Isoelectric point; MW: molecular weight (Da); Cys: cysteine; SignalP: signal peptide amino acid location. InterPro domains IPR023316 and SM00708, and families IPR006170 and PF01395. Unless otherwise indicated the “Conserved Cys” is six classical.</p

Number of GO categories exclusive and common to each species: (a) biological process, and (b) molecular function.

<p>A species was considered to have the category if it had more than 10 transcripts. The radii of the circles are proportional to the number of categories.</p

Phylogenetic relationships of: (a) target parasitoid putative OBPs (in red) and 215 putative other hymenopteran OBPs; (b) Detailed relationships of the putative TpodOBPs.

<p>The trees were constructed with MEGA 6.06 using a LG+G+I model. Values indicated at the nodes are bootstrap values based on 1,000 replicates presented with 50% cut-off bootstrap value for (a) and no cut-off for (b). The species names are abbreviated with four letters, and their full names with all accession numbers of the OBP amino acid sequences are provided in Table I in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132286#pone.0132286.s002" target="_blank">S2 File</a>.</p

Number of reads obtained from the RNA-Seq libraries and Illumina GAIIx sequencing for the stink bug antennae and whole-body parasitoid after quality control, and number of contigs assembled for each species.

<p>The minimum contig length was 300 bp for all samples. QC: quality control.</p