The codling moth Cydia pomonella, a major invasive pest of pome fruit, has spread around the globe in the last half century. We generated a chromosome-level scaffold assembly including the Z chromosome and a portion of the W chromosome. This assembly reveals the duplication of an olfactory receptor gene (OR3), which we demonstrate enhances the ability of C. pomonella to exploit kairomones and pheromones in locating both host plants and mates. Genome-wide association studies contrasting insecticide-resistant and susceptible strains identify hundreds of single nucleotide polymorphisms (SNPs) potentially associated with insecticide resistance, including three SNPs found in the promoter of CYP6B2. RNAi knockdown of CYP6B2 increases C. pomonella sensitivity to two insecticides, deltamethrin and azinphos methyl. The high-quality genome assembly of C. pomonella informs the genetic basis of its invasiveness, suggesting the codling moth has distinctive capabilities and adaptive potential that may explain its worldwide expansion.

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Testa color is an important trait of peanut (Arachis hypogaea L.). Peanuts with red testa are rich in anthocyanin, are very popular with consumers. However, genes responsible for the red testa trait in peanut are rarely reported. In order to ne map red testa gene, two F 4 populations were constructed through the cross of YZ9102 (pink testa) with ZH12 (red testa) and Zhanhong2 (red testa). Genetic analysis indicated that red testa was controlled by a single recessive gene, and named as AhRt2 (Red testa gene 2). Using BSA-seq approach, AhRt2 was preliminary identi ed in chromosome 12, and further mapped to a 530-kb interval using 220 recombinant lines through linkage mapping. Functional annotation, expression pro ling, and sequence variation analyses con rmed that the anthocyanin reductase (ANR), Arahy.IK60LM, was the most likely candidate gene for AhRt2. A SNP in the third exon of AhRt2 changed the encoding amino acids, was associated with red testa of peanut. In addition, a closely linkaged molecular marker to red testa trait was developed. Our result provide insight into the molecular mechanism underlying peanut testa color and provide valuable diagnostic marker for marker-assisted selected (MAS) breeding in peanut. Key MessageThe candidate recessive gene AhRt2 responsible for red testa of peanut was identi ed thorugh combined BSA-seq and linkage mapping approaches.

The bird cherry-oat aphid, Rhopalosiphum padi (L.), is one of the most abundant aphid pests of cereals and has a global distribution. Next-generation sequencing (NGS) is a rapid and efficient method for developing molecular markers. However, transcriptomic and genomic resources of R. padi have not been investigated. In this study, we used transcriptome information obtained by RNA-Seq to develop polymorphic microsatellites for investigating population genetics in this species. The transcriptome of R. padi was sequenced on an Illumina HiSeq 2000 platform. A total of 114.4 million raw reads with a GC content of 40.03% was generated. The raw reads were cleaned and assembled into 29,467 unigenes with an N50 length of 1,580 bp. Using several public databases, 82.47% of these unigenes were annotated. Of the annotated unigenes, 8,022 were assigned to COG pathways, 9,895 were assigned to GO pathways, and 14,586 were mapped to 257 KEGG pathways. A total of 7,936 potential microsatellites were identified in 5,564 unigenes, 60 of which were selected randomly and amplified using specific primer pairs. Fourteen loci were found to be polymorphic in the four R. padi populations. The transcriptomic data presented herein will facilitate gene discovery, gene analyses, and development of molecular markers for future studies of R. padi and other closely related aphid species.