Project description:During the over 300 million years of co-evolution between herbivorous insects and their host plants, a dynamic equilibrium of evolutionary arms race has been established. However, the co-adaptation between insects and their host plants is a complex process, often driven by multiple evolutionary mechanisms. We found that various lepidopteran pests that use maize as a host exhibit differential adaptation to the plant secondary metabolites, benzoxazinoids (BXs). Notably, the Spodoptera genus, including Spodoptera frugiperda (fall armyworm) and Spodoptera litura (cotton leafworm), demonstrate greater tolerance to BXs compared to other insects. Through comparative transcriptomic analysis of the midgut, we identified four candidate genes potentially involved in BXs detoxification in S. frugiperda. Subsequently, we confirmed two UGT genes, Sfru33T10 and Sfru33F32, as key players in BXs detoxification using CRISPR/Cas9 gene-editing technology. Phylogenetic analysis revealed that Sfru33T10 evolved independently within the Noctuidae family and is involved in the glycosylation of HDMBOA, while Sfru33F32 evolved independently within the Spodoptera genus and functions as a key detoxification enzyme responsible for the glycosylation of both DIMBOA and HMBOA. Our study demonstrates that the UGT gene family plays a crucial role in the adaptation of noctuid insects to maize, with multiple independent evolutionary events within the Noctuidae family and the Spodoptera genus contributing significantly to host adaptation.
Project description:Verson’s glands are segmental pairs of dermal glands attached to the epidermis in lepidopteran larvae. They produce macromolecules during intermolt period and empty them during each molt. Morphological, histochemical, developmental, and protein analysis studies have been conducted to determine the functions of Verson’s glands. However, the exact role of Verson’s glands remains unclear. In our previous study, a strain of transgenic fall armyworm, Spdoptera frugiperda expressing green fluorescence protein (GFP) and Systemic RNA interference defective protein 1 (SID-1) from Caenorhabditis elegans was established to improve RNA interference (RNAi) efficiency. Unexpectedly, we found that GFP fluorescence was significantly brighter in Verson’s glands than in other tissues. Also, RNAi efficiency improved more in Verson’s glands than in other tissues. We took advantage of improved RNAi efficiency to explore the function of Verson’s glands. RNA-seq analysis revealed that genes highly expressed in Verson’s glands code for cuticular proteins, molting fluid proteins, hemolymph proteins, and antimicrobial peptides. Injection of dsRNA targeting essential genes interfered with Verson’s glands growth. These studies revealed that Verson’s glands contribute to hemolymph, cuticle, molting fluid, and immune response during molting. These studies also provide useful tools for future research in identifying the physiological role of Verson’s glands in lepidopteran insects.
Project description:Fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is an invasive and noxious pest of maize (Zea mays), which is native to tropical and subtropical regions of America. It is now an invasive pest of Indian Sub continent, first reported from Karnataka on maize in 2018.
Project description:The mechanism of evolution in different conditions can be examined from various molecular aspects that constitute a cell, namely, transcript, protein or metabolite abundance. We have analyzed transcript and metabolite abundance changes in evolved and ancestor strains in three different evolutionary conditions, namely, excess-nutrient adaptation, prolonged stationary phase adaptation and adaptation due to environmental shift, in two different strains of Escherichia coli K-12 (MG1655 and DH10B).
Project description:The fall armyworm (FAW; Spodoptera frugiperda) is one of the major agricultural pest insects. FAW is native to the Americas, and its invasion was first reported in West Africa in 2016. Then it quickly spread through Africa, Asia, and Oceania, becoming one of the main threats to corn production. We analyzed whole genome sequences of 177 FAW individuals from 12 locations on four continents to infer evolutionary processes of invasion. Principal component analysis from the TPI gene and whole genome sequences shows that invasive FAW populations originated from the corn strain. Ancestry coefficient and phylogenetic analyses from the nuclear genome indicate that invasive populations are derived from a single ancestry, distinct from native populations, while the mitochondrial phylogenetic tree supports the hypothesis of multiple introductions. Adaptive evolution specific to invasive populations was observed in detoxification, chemosensory, and digestion genes. We concluded that extant invasive FAW populations originated from the corn strain with potential contributions of adaptive evolution.
Project description:The threat of invasive species is increasing with the expansion of global trade and habitat disruption. A recent example is the establishment of fall armyworm (FAW), a noctuid moth native to the Americas, into most of the Eastern Hemisphere with projections of significant economic losses on a global scale. The species has traditionally been subdivided into two populations that differ in their propensity to use different plant hosts, a phenotype with clear relevance for identifying crops at risk. However, inconsistencies in the genetic and phenotypic descriptions of these "host strains" has led to controversy about their composition and even existence. In this study, the locus for the Triosephosphate isomerase gene (Tpi) is used both as a host strain marker and for phylogenetic analysis. Association of the host choice phenotype with the Tpi-derived phylogenetic tree uncovered genetic differentiation between populations that supports the existence of the host strains and provided evidence that they are subject to different selection pressures. This correspondence of differential host use with Tpi was demonstrated for populations from a broad geographical range and supports the involvement of one or more Z-chromosome functions controlling the phenotype. Comparisons of collections from multiple locations identified significant differences in the efficacy of different molecular markers that implicate regional variations in host strain behavior.