The Principal Salivary Gland Is the Primary Source of Digestive Enzymes in the Saliva of the Brown Marmorated Stink Bug, Halyomorpha halys

Abstract

The brown marmorated stink bug, Halyomorpha halys, is an invasive, phytophagous stink bug of global importance for agriculture. Tissue-specific transcriptomic analysis of the accessory salivary gland, principal salivary gland (PSG) and gut resulted in identification of 234 putative protease and 166 putative nuclease sequences. By mapping the previously reported proteomes of H. halys watery saliva (WS) and sheath saliva to protein sequences translated from the assembled transcripts, 22 proteases and two nucleases in the saliva were identified. Of these, 19 proteases and both nucleases were present in the WS. The majority of proteases and nucleases found in WS were derived from the PSG, in line with ultrastructural observations, which suggest active protein synthesis and secretion by this tissue. The highly transcribed digestive proteases and nucleases of H. halys were similar to those of the southern green stink bug, Nezara viridula, indicating that these pentatomid stink bugs utilize a similar suite of proteases and nucleases for digestion of plant material. The comprehensive data set for the H. halys salivary glands and gut generated by this study provides an additional resource for further understanding of the biology of this pestiferous species.

Transcriptomic and proteomic analysis of putative digestive proteases in the salivary gland and gut of Empoasca (Matsumurasca) onukii Matsuda

“…In addition, certain numbers of the transcripts identi ed from the proteomic pro les were associated with the increase of the FPKM (expected number of Fragments Per Kilobase of transcript sequence per Million base pairs sequenced) value of the transcripts (Fig. 2b), which were similar to the previous observations in the investigation of proteases of stinkbugs [21,26].…”

“…In addition, the majority of these transcripts of the proteases highly accumulated in the principle salivary gland (PSG) of H. halys and N. vididula. These results indicated that in both stink bugs, PSGs were the major sources to release proteases into the saliva [21].…”

“…Most of the cluster I serine proteases showed low to moderate transcriptional abundance in the gut, while higher expressions in the gut were observed in most of the cluster II serine proteases. Signi cantly, a branch of serine proteases in cluster I, including NcSerineProtease-6, EMoSerineProtease-4, -36, ApSerineProtease-1, -2, -6, and multiple other serine proteases, which were highly transcribed in the SG of stink bugs [21,26], were grouped together (the clade colored red in Fig. 6).…”

“…Salivary protein pro les have been studied at both transcriptomic and proteomic levels for a wide range of hemipteran insects, including stink bugs, aphids, leafhoppers and planthoppers [15][16][17][18][19][20][21][22][23]. Salivary proteomic pro ling has revealed that saliva from hemipteran insects mainly contains various enzyme families, including oxidoreductases, hydrolases, transferases, Ca 2+ -binding proteins and proteases/peptidases [15,18,20,24,25].…”

“…Transcriptomic analysis coupled with proteomic pro ling is an effective strategy for identi cation of functional proteins in the SG and gut of hemipterans [21,26]. For example, proteases in the SG and gut of the two devastating pentatomid stink bugs, Halyomorpha halys and Nezara viridula, were investigated to identify proteases highly expressed in each tissue [21,26]. Furthermore, mapping of SG transcripts of H. halys to the protein pro les of watery saliva, which is the saliva secreted into the host plants, revealed 22 abundant digestive proteases.…”