Pseudotaxus chienii
, the only species in the genus
Pseudotaxus
, is closely related to
Taxus
genus. Whether
P. chienii
can produce paclitaxel has long remained controversial. Here, we present a chromosome-level, haplotype-resolved genome of
P. chienii
, with each haplotype ( ~ 15.4 Gb) exhibiting high continuity and completeness. We identify a structurally conserved yet physically dispersed genomic region, termed the Taxane Biosynthetic Archipelago (TBA), containing three biosynthetic gene clusters and collinear core genes essential for taxane biosynthesis. Integrative transcriptomic, metabolite, and heterologous enzymatic analyses reveal that while
P. chienii
retains a largely conserved genomic architecture associated with paclitaxel biosynthesis, its terminal pathway shows severe functional degradation and may have largely lost the functional capacity for paclitaxel production. Concurrently, it exhibits significant accumulation of taxinine J. This study provides an evolutionary framework for interpreting the long-standing debate on paclitaxel production beyond
Taxus
, and understanding the evolutionary decay of complex specialized pathways.
Huan Wang, Hai-Dong Chen, Ya-Ping Sun et al.· Nature Communications· 0 citations
The olive family (Oleaceae) comprises numerous species of economic, horticultural, and medicinal importance. Despite its significance, the evolutionary history of this complex family remains enigmatic. Here, we generated a high-quality haplotype-resolved genome of Forsythia suspensa, a distylous species that occupies a key phylogenetic position in Oleaceae. The two haplotypes exhibit significant allelic divergence with potential allele-specific regulation. We reconstructed the polyploidization history of Oleaceae by confirming and precisely dating a shared whole-genome triplication (WGT) and an independent whole-genome duplication (WGD) event. We revealed a complex reticulate evolution that gave rise to the tribe Oleeae: an initial hybridization between Forsythieae (♂) and Jasmineae (♀), a subsequent backcrossing event, and a final WGD. We identified a novel tandemly duplicated pectin methylesterase inhibitor (PMEI) gene cluster that regulates filament length and pollen size via restricting cell elongation in the long-styled morph. Dosage augmentation via stepwise cluster formation (0.99-3.83 Mya) may contribute to maintaining stamen traits of the long-styled morph. These FsPMEIs are co-expressed with many cell wall-related genes, suggesting a functional link in cell wall modification. Our study reveals the reticulate evolution in Oleaceae and a novel gene cluster controlling stamen development in F. suspensa, provides valuable haplotype-resolved genomic resources for heterostylous species, offering novel framework and molecular pathways to understand plant adaptive evolution.
Quanling Zhang, Ezi Zhao, Xiao-Min Fu et al.· Plant Physiology· 0 citations
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