Role of digestive protease enzymes and related genes in host plant adaptation of a polyphagous pest, Spodoptera frugiperda

Abstract

The evolutionary success of phytophagous insects depends on their ability to efficiently exploit plants as a source of energy for survival. Herbivorous insects largely depend on the efficiency, flexibility, and diversity of their digestive physiology and sophistication of their detoxification system to use chemically diverse host plants as food sources. The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a polyphagous pest of many commercially important crops. To elucidate the ability of this insect pest to adapt to host plant mechanisms, we evaluated the impact of primary (corn) and alternate (rice) host plants after 11 generations on gut digestive enzymatic activity and expression profiles of related genes. Results indicated that the total protease and class-specific trypsinand chymotrypsin-like protease activity of S. frugiperda significantly differed among host plant treatments. The class-specific protease profiles greatly differed in S. frugiperda midguts upon larval exposure to different treatments with inhibitors compared with treatments without inhibitors. Similarly, the single and cumulative effects of the enzymespecific inhibitors TLCK, TPCK, and E-64 significantly increased larval mortality and reduced larval growth/mass across different plant treatments. Furthermore, the quantitative reverse transcription polymerase chain reaction results revealed increased transcription of two trypsin (SfTry-3, SfTry-7) and one chymotrypsin gene (Sfchym-9), which indicated that they have roles in host plant adaptation. Knockdown of these genes resulted in significantly reduced mRNA expression levels of the trypsin genes. This was related to the increased mortality observed in treatments compared with the dsRED control. This result indicates possible roles of S. frugiperda gut digestive enzymes and related genes in host plant adaptation.

Molecular characterization and functional analysis of cytochrome P450-mediated detoxification CYP302A1 gene involved in host plant adaptation in Spodoptera frugieprda

“…The midguts of the larvae were dissected at 48, 72 and 96 h after feeding on the corn, rice plant and an artificial diet (Ck) as a control treatment according to ( Hafeez et al., 2021b ). Larvae from each treatment were cold immobilized and their midguts were separated in 0.1 mol/L phosphate-buffered saline with pH 7.4.…”

Four MicroRNAs, miR-13b-3p, miR-278-5p, miR-10483-5p, and miR-10485-5p, Mediate Insecticide Tolerance in Spodoptera frugiperda

“…Spodoptera frugiperda is native to North America, South America, and subtropical regions and feeds on a variety of crops including corn, soybeans, cotton, and rice (Gouin et al, 2017). Two biotypes, the "corn-strain" and "rice-strain", have been identified for S. frugiperda (Hafeez et al, 2021). S. frugiperda has strong migratory capacity, first found in Central and Western Africa in 2016, moving into India in 2018, and invading China in January 2019 (Junior et al, 2012;Goergen et al, 2016;Early et al, 2018;Li et al, 2020).…”

Behavioral and Physiological Plasticity Provides Insights into Molecular Based Adaptation Mechanism to Strain Shift in Spodoptera frugiperda

“…Two populations of S. frugiperda were established, designated as Corn-pop and Rice-pop, from the original population by rearing each continuously on their respective plants. Both populations were reared according to the method described by [ 30 ] for 20 generations.…”

“…In most cases, this generally involves the induction of a cocktail gut digestive enzymes that allow the exploitation of the toxic phytochemicals encountered during feeding [ 24 , 27 ]. The expression of gut digestive plasticity to cope with plant chemical toxicants as an adaptive mechanism to noxious chemical containing host plants has been documented in a number of herbivorous insects including Busseola fusca [ 28 ], Helicoverpa armigera [ 29 ], Spodoptera frugiperda [ 30 ], Heliothis virescens [ 31 ] and Manduca sexta [ 32 ]. In herbivorous insects, digestive proteases with diverse structures and functions play an important role in host plant adaptation.…”