Allelic differences of clustered terpene synthases contribute to correlated intra-specific variation of floral and herbivory induced volatiles in a wild tobacco

Abstract

O_LIPlant volatile emissions can recruit predators of herbivores for indirect defence and attract pollinators to aid in pollination. Although volatiles involved in defence and pollinator attraction are primarily emitted from leaves and flowers, respectively, they will co-evolve if their underlying genetic basis is intrinsically linked, either due to pleiotropy or genetic linkage. However, direct evidence of co-evolving defence and floral traits is scarce. C_LIO_LIWe characterized intra-specific variation of herbivory-induced plant volatiles (HIPVs), the key components of indirect defence against herbivores, and floral volatiles in the wild tobacco Nicotiana attenuata. C_LIO_LIWe found that variation of (E)-{beta}-ocimene and (E)--bergamotene contributed to the correlated changes in HIPVs and floral volatiles among N. attenuata natural accessions. Intra-specific variations of (E)-{beta}-ocimene and (E)--bergamotene emissions resulted from allelic variation of two genetically co-localized terpene synthase genes, NaTPS25 and NaTPS38 respectively. C_LIO_LIAnalyzing haplotypes of NaTPS25 and NaTPS38 revealed that allelic variations of NaTPS25 and NaTPS38 resulted in correlated changes of (E)-{beta}-ocimene and (E)--bergamotene emission in HIPVs and floral volatiles in N. attenuata. C_LIO_LITogether, these results provide evidence that pleiotropy and genetic linkage result in correlated changes in defences and floral signals in natural populations, and the evolution of plant volatiles is likely under diffuse selection. C_LI