Comparative transcriptome analysis provides insights of anti‐insect molecular mechanism of Cassia obtusifolia trypsin inhibitor against Pieris rapae

Abstract

Pieris rapae, a serious Lepidoptera pest of cultivated crucifers, utilizes midgut enzymes to digest food and detoxify secondary metabolites from host plants. A recombinant trypsin inhibitor (COTI)1 from nonhost plant, Cassia obtusifolia, significantly decreased activities of trypsin-like proteases in the larval midgut on Pieris rapae and could suppress the growth of larvae. In order to know how COTI took effect, transcriptional profiles of P. rapae midgut in response to COTI was studied. A total of 51,544 unigenes were generated and 45.86% of which had homologs in public databases. Most of the regulated genes associated with digestion, detoxification, homeostasis, and resistance were downregulated after ingestion of COTI. Meanwhile, several unigenes in the integrin signaling pathway might be involved in response to COTI. Furthermore, using comparative transcriptome analysis, we detected differently expressing genes and identified a new reference gene, UPF3, by qRT-polymerase chain reaction (PCR). Therefore, it was suggested that not only proteolysis inhibition, but also suppression of expression of genes involved in metabolism, development, signaling, and defense might account for the anti-insect resistance of COTI. K E Y W O R D SCassia obtusifolia, nonhost plant, physiological response, Pieris rapae, trypsin inhibitor

Comparative gut transcriptome analysis of Diatraea saccharalis in response to the dietary source

“…The gut is the first defence barrier against pathogens and toxins acquired through food [2,62]. Well-characterized families of enzymes that play crucial roles in detox pathways, such as GST, UGT, and CYP proteins and peroxidases, were identified as DEGs here and in previous studies on Lepidoptera [9,12,46,61,63,64]. Most of these gene families have variable expression profiles; some transcripts are overexpressed in sugarcane-fed larvae and others overexpressed in artificial diet-fed larvae, probably due to the high structural and functional diversity of these families (Fig 5).…”

“…saccharalis . Tissue-specific transcriptomes of other lepidopterans have shown that despite the high variability in contig numbers, the number of protein-coding unigenes is consistently between 20,000 and 30,000 [ 9 , 12 , 46 – 48 ]. Insect transcriptomes have been sequenced at higher frequency in the last five years, proving to be useful as a descriptive tool and an invaluable source of sequences for studies researching gene function and design of RNAi experiments [ 2 , 10 , 13 , 49 , 50 ].…”

“…Major digestion steps in insects are performed by catalytic enzymes produced by the gut cells [ 7 ]. It has been demonstrated that the expression levels of genes encoding digestive enzymes are variable depending on the food source and the degree of insect specialization [ 46 , 59 – 61 ]. Our enrichment analysis elucidated several major digestive processes, such as the metabolism of lipids and proteins, which were overexpressed in larvae fed on an artificial diet.…”

“…The large number of identified genes encoding serine proteases, such as trypsin and chymotrypsin, probably indicated a response to the presence of proteinase inhibitors in the diet. These molecules induce the expression of many isoforms of serine protease genes in many insects [2,46,59]. Notably, genes associated with carbohydrate metabolism were not significant among the DEGs.…”

Influence of Different Cowpea (<i>Vigna unguiculata</i> (L.) Walp.) Genotypes from Burkina Faso on Proteases Inhibition

“…Storage organs of plant such as seeds, tubers and also leaves, flowers, and fruits contain different types of protease inhibitors (PIs) which is able to inhibit some enzymes like trypsin, pepsin and chymotrypsin [9,10,7,11]. PIs are small proteins or peptides that inhibit the catalytic action of proteases by forming stoichiometric and stable complexes with their proteolytic enzymes blocking or altering the active site [11][12][13]. Protease inhibitors in legume seed can inhibit pancreatic serine proteases, thus slowing down protein digestion at the small intestine [14,15].…”