Nature Plants最新文献

Orchids constitute one of the most diverse families of angiosperms, yet their genome evolution and diversity remain unclear. Here we construct and analyse chromosome-scale de novo assembled genomes of 17 representative accessions spanning 12 sections in Dendrobium, one of the largest orchid genera. These accessions represent a broad spectrum of phenotypes, lineages and geographical distributions. We first construct haplotype-resolved genomes for a Dendrobium hybrid and uncover haplotypic variations and allelic imbalance in the heterozygous genome, demonstrating the significance of diverse ancestry. At Dendrobium genus-wide scale, we further elucidate phylogenetic relationships, evolutionary dynamics, entire gene repertoire, and the mechanisms of preserving ancient genetic variants and rapid recent genome evolution for habitat adaption. We also showcase distinctive evolutionary trajectories in MADS-box and PEBP families over 28 Ma. These results considerably contribute to unearthing the mystery of orchid origin, evolution and diversification, laying the foundation for efficient use of genetic diversity in breeding.

Pseudouridine (Ψ) is the most abundant RNA modification, yet studies of Ψ have been hindered by a lack of robust methods to profile comprehensive Ψ maps. Here we utilize bisulfite-induced deletion sequencing to generate transcriptome-wide Ψ maps at single-base resolution across various plant species. Integrating ribosomal RNA, transfer RNA and messenger RNA Ψ stoichiometry with mRNA abundance and polysome profiling data, we uncover a multilayered regulation of translation efficiency through Ψ modifications. rRNA pseudouridylation could globally control translation, although the effects vary at different rRNA Ψ sites. Ψ in the tRNA T-arm loop shows strong positive correlations between Ψ stoichiometry and the translation efficiency of their respective codons. We observed a general inverse correlation between Ψ level and mRNA stability, but a positive correlation with translation efficiency in Arabidopsis seedlings. In conclusion, our study provides critical resources for Ψ research in plants and proposes prevalent translation regulation through rRNA, tRNA and mRNA pseudouridylation.

Plant cuticular waxes serve as highly responsive adaptations to variable environments^{1,2,3,4,5,6,7}. Aliphatic waxes consist of very-long-chain (VLC) compounds produced from 1-alcohol- or alkane-forming pathways^5,8. The existing variation in 1-alcohols and alkanes across Arabidopsis accessions revealed that 1-alcohol amounts are negatively correlated with aridity factors, whereas alkanes display the opposite behaviour. How carbon resources are allocated between the 1-alcohol and alkane pathways responding to environmental stimuli is still largely unknown. Here, in Arabidopsis, we report a novel 1-alcohol biosynthesis pathway in which VLC acyl-CoAs are first reduced to aldehydes by CER3 and then converted into 1-alcohols via a newly identified putative aldehyde reductase SOH1. CER3, previously shown to interact with CER1 in alkane synthesis, is identified to interact with SOH1 as well, channelling wax precursors into either alcohol- or alkane-forming pathways, and the directional shunting of these precursors is tightly regulated by the SOH1–CER3–CER1 module in response to environmental conditions.