Cowpea bruchid midgut transcriptome response to a soybean cystatin – costs and benefits of counter‐defence

Abstract

The insect digestive system is the first line of defence protecting cells and tissues of the body from a broad spectrum of toxins and antinutritional factors in its food. To gain insight into the nature and breadth of genes involved in adaptation to dietary challenge, a collection of 20 352 cDNAs was prepared from the midgut tissue of cowpea bruchid larvae (Callosobruchus maculatus) fed on regular diet and diets containing antinutritional compounds. Transcript responses of the larvae to dietary soybean cystatin (scN) were analysed using cDNA microarrays, followed by quantitative real-time PCR (RT-PCR) confirmation with selected genes. The midgut transcript profile of insects fed a sustained sublethal scN dose over the larval life was compared with that of insects treated with an acute high dose of scN for 24 h. A total of 1756 scN-responsive cDNAs was sequenced; these clustered into 967 contigs, of which 653 were singletons. Many contigs (451) did not show homology with known genes, or had homology only with genes of unknown function in a Blast search. The identified differentially regulated sequences encoded proteins presumptively involved in metabolism, structure, development, signalling, defence and stress response. Expression patterns of some scN-responsive genes were consistent in each larval stage, whereas others exhibited developmental stage-specificity. Acute (24 h), high level exposure to dietary scN caused altered expression of a set of genes partially overlapping with the transcript profile seen under chronic lower level exposure. Protein and carbohydrate hydrolases were generally up-regulated by scN whereas structural, defence and stress-related genes were largely down-regulated. These results show that insects actively mobilize genomic resources in the alimentary tract to mitigate the impact of a digestive protease inhibitor. The enhanced or restored digestibility that may result is possibly crucial for insect survival, yet may be bought at the cost of weakened response to other stresses.

Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

“…This is the first time that this type of compensation is observed in L. migratoria . Partial reliance on insensitive proteases as counter defence however has already been observed in different other insects, including: Helicoverpa armigera, Spodoptera exigua , Callosobruchus maculatus, Leptinotarsa decemlineata and Schistocerca gregaria 914162728. Our findings confirm that regulating the expression of proteolytic enzymes is a common strategy applied by insects to evade loss of proteolytic activity caused by the presence of PI in the gut.…”

“…This could be consistent with an exploitation of alternative sources of energy to compensate for a loss in energy normally derived from protein digestion1418. On the other hand, a β-glucosidase (encoded by 3 transcripts), two hexokinases and cellulase were found downregulated under the same conditions.…”

Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

“…This is the first time that this type of compensation is observed in L. migratoria . Partial reliance on insensitive proteases as counter defence however has already been observed in different other insects, including: Helicoverpa armigera, Spodoptera exigua , Callosobruchus maculatus, Leptinotarsa decemlineata and Schistocerca gregaria 914162728. Our findings confirm that regulating the expression of proteolytic enzymes is a common strategy applied by insects to evade loss of proteolytic activity caused by the presence of PI in the gut.…”

“…This could be consistent with an exploitation of alternative sources of energy to compensate for a loss in energy normally derived from protein digestion1418. On the other hand, a β-glucosidase (encoded by 3 transcripts), two hexokinases and cellulase were found downregulated under the same conditions.…”

Antagonistic Regulation, Yet Synergistic Defense: Effect of Bergapten and Protease Inhibitor on Development of Cowpea Bruchid Callosobruchus maculatus

“…Despite the notable plant protective role, many herbivorous insects have evolved various resistance strategies to evade plant defense, and the front line of battle is the digestive canal. Consistently, our microarray analyses demonstrated that the midgut gene expression program in cowpea bruchids changes in response to dietary challenges, whether the challenge was derived from scN [32] or bergapten (Fig. 2).…”

A COMPLEX OF GENES INVOLVED IN ADAPTATION OF Leptinotarsa decemlineata LARVAE TO INDUCED POTATO DEFENSE

“…However, expression of intestain E genes remains unchanged in short-and long-term adaptation. Similar up-and downregulation, as well as unchanged levels of the main class of digestive protease genes in response to PI ingestion, has been observed in Helicoverpa armigera, H. zea, Agrotis ipsilon, C. maculatus, and T. castaneum larvae (Bown et al, 1997(Bown et al, , 2004;;Mazumdar-Leighton and Broadway, 2001;Moon et al, 2004;Chi et al, 2009;Oppert et al, 2010). While inhibitor-insensitive proteases in larval guts of H. zea and A. ipsilon were induced within 2 h after PI incorporation into the diet (Mazumdar-Leighton and Broadway, 2001), in our experiments and those of Gruden et al (2004) expression of specific proteases was induced later than 24 h after feeding on MeJA-induced potato leaves (Fig.…”

Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

“…This is the first time that this type of compensation is observed in L. migratoria . Partial reliance on insensitive proteases as counter defence however has already been observed in different other insects, including: Helicoverpa armigera, Spodoptera exigua , Callosobruchus maculatus, Leptinotarsa decemlineata and Schistocerca gregaria 914162728. Our findings confirm that regulating the expression of proteolytic enzymes is a common strategy applied by insects to evade loss of proteolytic activity caused by the presence of PI in the gut.…”

“…This could be consistent with an exploitation of alternative sources of energy to compensate for a loss in energy normally derived from protein digestion1418. On the other hand, a β-glucosidase (encoded by 3 transcripts), two hexokinases and cellulase were found downregulated under the same conditions.…”

Antagonistic Regulation, Yet Synergistic Defense: Effect of Bergapten and Protease Inhibitor on Development of Cowpea Bruchid Callosobruchus maculatus

“…Despite the notable plant protective role, many herbivorous insects have evolved various resistance strategies to evade plant defense, and the front line of battle is the digestive canal. Consistently, our microarray analyses demonstrated that the midgut gene expression program in cowpea bruchids changes in response to dietary challenges, whether the challenge was derived from scN [32] or bergapten (Fig. 2).…”

A COMPLEX OF GENES INVOLVED IN ADAPTATION OF Leptinotarsa decemlineata LARVAE TO INDUCED POTATO DEFENSE

“…However, expression of intestain E genes remains unchanged in short-and long-term adaptation. Similar up-and downregulation, as well as unchanged levels of the main class of digestive protease genes in response to PI ingestion, has been observed in Helicoverpa armigera, H. zea, Agrotis ipsilon, C. maculatus, and T. castaneum larvae (Bown et al, 1997(Bown et al, , 2004;;Mazumdar-Leighton and Broadway, 2001;Moon et al, 2004;Chi et al, 2009;Oppert et al, 2010). While inhibitor-insensitive proteases in larval guts of H. zea and A. ipsilon were induced within 2 h after PI incorporation into the diet (Mazumdar-Leighton and Broadway, 2001), in our experiments and those of Gruden et al (2004) expression of specific proteases was induced later than 24 h after feeding on MeJA-induced potato leaves (Fig.…”

Transcriptional Analysis of The Adaptive Digestive System of The Migratory Locust in Response to Plant Defensive Protease Inhibitors

“…This is the first time that this type of compensation is observed in L. migratoria . Partial reliance on insensitive proteases as counter defence however has already been observed in different other insects, including: Helicoverpa armigera, Spodoptera exigua , Callosobruchus maculatus, Leptinotarsa decemlineata and Schistocerca gregaria 914162728. Our findings confirm that regulating the expression of proteolytic enzymes is a common strategy applied by insects to evade loss of proteolytic activity caused by the presence of PI in the gut.…”

“…This could be consistent with an exploitation of alternative sources of energy to compensate for a loss in energy normally derived from protein digestion1418. On the other hand, a β-glucosidase (encoded by 3 transcripts), two hexokinases and cellulase were found downregulated under the same conditions.…”

Antagonistic Regulation, Yet Synergistic Defense: Effect of Bergapten and Protease Inhibitor on Development of Cowpea Bruchid Callosobruchus maculatus

“…Despite the notable plant protective role, many herbivorous insects have evolved various resistance strategies to evade plant defense, and the front line of battle is the digestive canal. Consistently, our microarray analyses demonstrated that the midgut gene expression program in cowpea bruchids changes in response to dietary challenges, whether the challenge was derived from scN [32] or bergapten (Fig. 2).…”

A COMPLEX OF GENES INVOLVED IN ADAPTATION OF Leptinotarsa decemlineata LARVAE TO INDUCED POTATO DEFENSE

“…However, expression of intestain E genes remains unchanged in short-and long-term adaptation. Similar up-and downregulation, as well as unchanged levels of the main class of digestive protease genes in response to PI ingestion, has been observed in Helicoverpa armigera, H. zea, Agrotis ipsilon, C. maculatus, and T. castaneum larvae (Bown et al, 1997(Bown et al, , 2004;;Mazumdar-Leighton and Broadway, 2001;Moon et al, 2004;Chi et al, 2009;Oppert et al, 2010). While inhibitor-insensitive proteases in larval guts of H. zea and A. ipsilon were induced within 2 h after PI incorporation into the diet (Mazumdar-Leighton and Broadway, 2001), in our experiments and those of Gruden et al (2004) expression of specific proteases was induced later than 24 h after feeding on MeJA-induced potato leaves (Fig.…”