Differential expression profiling of Oxycarenus laetus Kirby (Hemiptera: Lygaeidae) upon exposure to gossypol.

BACKGROUND: Gossypium hirsutum seeds are rich in gossypol. In addition to its diverse beneficial properties, it is a known anti-fertility inducing agent in humans. Oxycarenus laetus feeds on the cottonseeds and yet its courtship, mating and reproduction is unaffected. METHODS AND RESULTS: In this study, we performed a transcriptome profiling of O. laetus fed on Abutilon indicum (AB-no gossypol), G. hirsutum (GH-natural gossypol) and 1400 ppm commercial gossypol-soaked GH seeds (GHGO). Illumina NextSeq-500 paired-end 75 bp reads were generated and de novo assembled (48,214 genes) to identify the differentially expressed transcripts (DET) between the samples. Gene enrichment, KEGG pathway and cluster profiling of the DETs resulted in the identification of vital genes involved in the detoxification, pheromone biosynthesis, cuticle protein in the GHGO sample. Cyp4C1, Cyp6a13, Cyp6a14, Cyp4g15, Cyp4em8, Cyp303a1 were the detoxification related genes identified. Similarly, SDR dehydrogenase family 11 and fatty acid synthase in pheromone biosynthesis and cuticle proteins (RR1 and RR2) coding transcripts were found to be differentially expressed. CONCLUSION: This is the first study to report the expression of genes induced by gossypol in O. laetus. Based on the findings from the DET analysis, we conclude that the detoxification related genes of gossypol treated samples were affected.

Gut Metagenomic Profiling of Gossypol Induced Oxycarenus laetus (Hemiptera: Lygaeidae) Reveals Gossypol Tolerating Bacterial Species.

Oxycarenus laetus is a cotton pest that primarily feeds on seeds that are rich in gossypol. Though gossypol is toxic to general herbivores, O. laetus does not show such complications and instead grows and reproduces well on cotton plants compared to its other hosts. In this study, we have fed O. laetus with natural and induced gossypol-based diets to explore the difference in its gut microbiota. We performed NGS 16S rRNA amplicon sequencing on the Illumina MiSeq platform and analyzed the data using the QIIME2 pipeline supplemented with Greengenes and EZBioCloud reference databases. We also used culture-based methods to identify a few abundant gut bacteria present in O. laetus. Enterococcus faecalis, Wolbachia bourtzisii, Wolbachia pipientis, Corynebacterium glyciniphilum, Staphylococcus sciuri, and Kocuria rosea were some of the major species that formed the core gut microbiome of O. laetus. We have also observed that some species were present only in the sample with the highest concentration of gossypol, signifying that they might have the potential to degrade gossypol. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00964-0.

Complete mitochondrial genome sequencing of Oxycarenus laetus (Hemiptera: Lygaeidae) from two geographically distinct regions of India.

Oxycarenus laetus is a seed-sap sucking pest affecting a variety of crops, including cotton plants. Rising incidence and pesticide resistance by O. laetus have been reported from India and neighbouring countries. In this study, O. laetus samples were collected from Bhatinda and Coimbatore (India). Pure mtDNA was isolated and sequenced using Illumina MiSeq. Both the samples were found to be identical species (99.9%), and the complete genome was circular (15,672 bp), consisting of 13 PCGs, 2 rRNA, 23 tRNA genes, and a 962 bp control region. The mitogenome is 74.1% AT-rich, 0.11 AT, and - 0.19 GC skewed. All the genes had ATN as the start codon except cox1 (TTG), and an additional trnT was predicted. Nearly all tRNAs folded into the clover-leaf structure, except trnS1 and trnV. The intergenic space between trnH and nad4, considered as a synapomorphy of Lygaeoidea, was displaced. Two 5 bp motifs AATGA and ACCTA, two tandem repeats, and a few microsatellite sequences, were also found. The phylogenetic tree was constructed using 36 mitogenomes from 7 super-families of Hemiptera by employing rigorous bootstrapping and ML. Ours is the first study to sequence the complete mitogenome of O. laetus or any Oxycarenus species. The findings from this study would further help in the evolutionary studies of Lygaeidae.