Genetic analyses and detection of point mutations in the acetylcholinesterase-1 gene associated with organophosphate insecticide resistance in fall armyworm (Spodoptera frugiperda) populations from Uganda

Abstract Background The fall armyworm (FAW), Spodoptera frugiperda; J.E. Smith (Lepidoptera: Noctuidae), is now an economically important pest that causes huge losses to maize productivity in sub-Saharan Africa. Variations in sub-population genetics and the processes of rapid adaptation underpinning the invasion remain unclear. For this, the genetic identity and diversity of FAW populations in Uganda were revealed by sequencing 87 samples (collected across the country). Based on the partial mitochondrial cytochrome oxidase I (COI) gene polymorphisms, we further examined the mitochondrial haplotype configuration and compared the FAW in Uganda with sequences from other parts of the world. The molecular target for organophosphate and carbamate resistance, acetylcholinesterase, was also investigated. Results Analysis of the partial COI gene sequences showed the presence of both rice (predominant) and corn strain haplotypes, with a haplotype diversity of 0.382. Based on the COI marker, pairwise difference distribution analyses, and neutrality tests, showed that the FAW populations in Uganda and the rest of Africa are evolving neutrally, but those in America and Asia are undergoing expansion. Our findings support observations that invasive FAW populations throughout the rest of Africa and Asia share a common origin. Sequencing of the S. frugiperda ace-1 gene revealed four amino acid substitutions, two of which (A201S and F290V) were previously shown to confer organophosphate resistance in both S. frugiperda and several other insect species. The other two previously reported new variations in positions g-396 and g-768, are presumed to be related to the development of insecticide resistance. Conclusions This research has increased our knowledge of the genetics of FAW in Uganda, which is critical for pest surveillance and the detection of resistance. However, due to the low gene polymorphism of COI, more evolutionary studies incorporating the Spodoptera frugiperda whole-genome sequence are required to precisely understand the FAW population dynamics, introduction paths, origin, and subsequent spread

Nicotiana benthamiana, a popular model for genome evolution and plant–pathogen interactions

Nicotiana benthamiana originates from northern Australia and belongs to the Suaveolentes section. It is used extensively as a model organism for many types of research, including plant–pathogen interactions, RNA interference, and functional genomics. Recent publications that used N. benthamiana as a model for plant–pathogen interactions focused mainly on bacteria, viruses, oomycete, and fungi. Two different N. benthamiana whole genome assemblies were published in 2012. These assemblies have been improved and structurally annotated in later versions but are still incomplete. The lineage most widely used in research originates from a population that has retained a loss-of-function mutation in Rdr1 (RNA-dependent RNA polymerase 1) that makes it highly susceptible to viruses. In this chapter, we review some of the techniques used in N. benthamiana to study plant–pathogen interactions, including virus-induced gene silencing, transient protein expression by agroinfiltration, stable genetic manipulation, and transcriptomics analysis, and discuss some of the results. Descriptions and links to some of the most relevant online resources for N. benthamiana are also provided.Fil: Pombo, Marina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; ArgentinaFil: Rosli, Hernan Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; ArgentinaFil: Fernandez Pozo, Noé. University of Marburg; AlemaniaFil: Aureliano, Bombarely. Virginia Polytechnic Institute; Estados Unidos. Università degli Studi di Milano; Itali