Genome wide analysis identified 14 OBPs in B. tabaci Asia II-1, of which six are new to science. Phylogenetic analysis traced their diversity and evolutionary lineage among Hemipteran insects. Comparative analysis reclassified the OBP gene families among B. tabaci cryptic species: Asia I, II-1, MEAM1, and MED. The 14 OBPs were clustered on four chromosomes of B. tabaci. RT-qPCR showed high expression of OBP3 and 8 across all body tissues and OBP10 in the abdomen. Molecular docking showed that OBP 3 and 10 had high affinity bonding with different candidate ligands, with binding energies ranging from -5.0 to -7.7 kcal/mol. Competitive fluorescence binding assays revealed that β-caryophyllene and limonene had high binding affinities for OBP3 and 10, with their IC50 values ranging from 9.16 to 14 μmol·L-1 and KD values around 7 to 9 μmol·L-1. Behavioural assays revealed that β-caryophyllene and carvacrol were attractants, β-ocimene and limonene were repellents, and γ-terpinene and β-ocimene were oviposition deterrents to B. tabaci. Functional validation by RNAi demonstrated that OBP3 and OBP10 modulated host recognition of B. tabaci. This study expands our understanding of the genomic landscape of OBPs in B. tabaci, offering scope for developing novel pest control strategies.
Keywords: Bemisia tabaci Asia II-1; Functional characterization; Odorant binding protein.
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