Computational genome-wide survey of odorant receptors from two solitary bees Dufourea novaeangliae (Hymenoptera: Halictidae) and Habropoda laboriosa (Hymenoptera: Apidae)

Snehal D Karpe,Axel Brockmann,Surbhi Dhingra,R Sowdhamini

doi:10.1038/s41598-017-11098-z

Abstract

Olfactory/odorant receptors (ORs) probably govern eusocial behaviour in honey bees through detection of cuticular hydrocarbons (CHCs) and queen mandibular gland pheromones (QMP). CHCs are involved in nest-mate recognition whereas QMP acts as sex pheromone for drones and as retinue pheromone for female workers. Further studies on the effect of eusociality on the evolution of ORs are hindered by the non-availability of comprehensive OR sets of solitary species. We report complete OR repertoires from two solitary bees Dufourea novaeangliae (112 ORs) and Habropoda laboriosa (151 ORs). We classify these ORs into 34 phylogenetic clades/subfamilies. Differences in the OR sets of solitary and eusocial bees are observed in individual subfamilies like subfamily 9-exon (putative CHC receptors) and L (contains putative QMP receptor group). A subfamily (H) including putative floral scent receptors is expanded in the generalist honey bees only, but not in the specialists. On the contrary, subfamily J is expanded in all bees irrespective of their degree of social complexity or food preferences. Finally, we show species-lineage specific and OR-subfamily specific differences in the putative cis-regulatory DNA motifs of the ORs from six hymenopteran species. Out of these, [A/G]CGCAAGCG[C/T] is a candidate master transcription factor binding site for multiple olfactory genes.

Highlights

Honey bees are central to pollination of most flowering plants
D. novaeangliae is a soil-dwelling solitary species found in north-eastern USA, but it is an oligolege of pickerel weed (Pontederia cordata)[8, 9]
Our computational genome-wide survey for odorant receptors (ORs) genes in the solitary bees D. novaeangliae and H. laboriosa genome resulted in the identification of total 112 putative DnOrs and 151 putative HlOrs respectively (Table 1, Supplementary Tables S1 and S2 and Supplementary Data S1 and S2)

Summary

Introduction

Honey bees are central to pollination of most flowering plants. They contribute more than $15 billion to the value of agricultural crops each year in the USA alone[1]. D. novaeangliae is a soil-dwelling solitary species found in north-eastern USA, but it is an oligolege of pickerel weed (Pontederia cordata)[8, 9] It belongs to the family Halictidae and is the phylogenetically most distant bee species to the honey bees amongst all the sequenced species[7]. The best gene family candidates to test this hypothesis are olfactory/odorant receptors (ORs) Since they are known to undergo rapid birth and death evolution in response to the needs of each species[10, 11] and second, they seem to have expanded in eusocial bees and ants compared to distant solitary insect orders[12,13,14,15]. Our analysis sheds light on the evolution of ORs and their putative regulatory elements from solitary and eusocial honey bees

Methods

Results

Conclusion