Evolution of a novel and adaptive floral scent in wild tobacco

Abstract

1 Many plants emit diverse floral scents that mediate plant-environment interactions and 2 attain reproductive success. However, how plants evolve novel adaptive floral volatiles 3 remains unclear. Here, we show that in the wild tobacco, Nicotiana attenuata, a dominant 4species-specific floral volatile (benzyl acetone, BA) that attracts pollinators and deters 5 florivore is synthesized by phenylalanine ammonia-lyase 4 (NaPAL4), isoflavone reductase 3 6 (NaIFR3), and chalcone synthase 3 (NaCHAL3). Transient expression of NaFIR3 alone in N. 7 attenuata leaves is sufficient and necessary for ectopic foliar BA emissions, and the BA 8 emission level is increased by co-expressing NaIFR3 with NaPAL4 and NaCHAL3. 9 Independent changes in transcription in all three genes contributed to intraspecific variations 10 of floral BA emission. However, among species, the gain-of-expression in NaIFR3 resulted in 11 the biosynthesis of BA that was only found in N. attenuata. This study suggests that novel 12 metabolic pathways associated with adaptation can arise via re-configurations of gene 13 expression. 14

Establishment and application of Agrobacterium-delivered CRISPR/Cas9 system for wild tobacco (Nicotiana alata) genome editing

“…It has been introduced to other regions as an ornamental plant for its attractive and fragrant flowers that vary in color (Zheng et al, 2021;Zhang et al, 2023). As an important horticultural plant, the genes involved in the secondary metabolism pathway that regulate the fragrance and color of the flowers need to be further addressed (Raguso et al, 2003(Raguso et al, , 2006Fahnrich et al, 2011;Guo et al, 2020;Zheng et al, 2021). In its native wild habitats, N. alata encounters a range of biotic and abiotic stresses.…”