Cloning and characterization of protease inhibitor‐like cDNAs from the Hessian fly mayetiola destructor (SAY)

Abstract

Analysis of transcriptomes from the salivary glands and midgut of Hessian fly larvae Mayetiola destructor (say) identified a set of diverse cDNAs that encode proteins with a relatively high percentage (over 10%) of cysteinyl residues. Structural comparison of these putative proteins with known sequences in GenBank revealed that the positions of the cysteinyl residues in the identified proteins were highly conserved within a family of proteinase inhibitors despite very little overall sequence similarity. Phylogenetic analysis sorted this set of cDNAs into five different groups. To determine if these cDNAs indeed encode proteinase inhibitors, recombinant proteins were generated with two cDNAs from two different groups. Biochemical analysis of the recombinant proteins against commercial and insect gut proteinases demonstrated that the recombinant proteins are strong proteinase inhibitors with different specificities. Northern blot and real-time PCR analysis revealed that the different genes were expressed at different developmental stages and in different tissues. The overall results indicated that M. destructor contains a complex of genes that code for proteinase inhibitors which may regulate proteinase activities in different regulatory pathways. The GenBank accession numbers for the cDNAs in this paper were DQ232690 to DQ232718.

Massive Shift in Gene Expression during Transitions between Developmental Stages of the Gall Midge, Mayetiola Destructor

“…Many proteases including trypsins, chymtrypsins, cysteine proteases, and various carboxypeptidases play a role in food digestion in the midgut [ 42 – 45 ]. There are also a large number of protease inhibitors in the midgut, possibly serving as protection to inhibit the detrimental activity of ingested host proteases during feeding [ 46 , 47 ]. The increased synthesis of digestive proteases and protective protease-inhibitors is consistent with the observation that five-day old larvae ingest the largest amount of host fluid [ 41 ].…”

Reactive Oxygen Species Are Involved in Plant Defense against a Gall Midge

“…PCR primers and gene targets are listed in Supplemental Table S2. PCR programs and data analysis were conducted as described by Maddur et al (2006).…”

Peptidase inhibitors from the salivary glands of the cockroach Nauphoeta cinerea

“…Transcripts encoding peptidase inhibitors were identified in the salivary glands of the Hessian fly larvae (Mayetiola destructor). From the deduced amino acid sequence it was concluded that they belonged to the Ascaris family of peptidase inhibitors (Maddur et al, 2006) that are active against trypsin and chymotrypsin. The inhibitors are highly expressed in the salivary glands of the feeding 1st and 2nd instar larvae and are among secretions that are injected as saliva into the plant tissue and suppress the plant resistance mechanisms (Chen et al, 2008).…”