You, H.-L. | bioRxiv Science

bioRxiv2026

Evolutionary dynamics of the pan-centromere architecture in oaks

Centromeres ensure faithful chromosome segregation and genome stability, yet their DNA evolves rapidly, presenting a long-standing centromere paradox. Here we characterise the genomic and epigenomic architecture of >1,300 candidate centromeres from 111 high-quality Quercus (oak) genomes. We show that lineage-specific expansion of QuCEN146 satellite drives centromere turnover in oaks by displacing ancestral LTR-rich sequences into flanking regions, with genetic drift facilitating fixation of satellite-rich centromeres. Population-scale analyses in Q. serrata reveal extensive variation in satellite rich centromeres, generated by array expansion and contraction, strand-orientation shifts, and interspecific introgression. By contrast, LTR rich centromeres of Q. variabilis exhibit extremely low polymorphism and high collinearity across populations, sustained by suppressed local recombination, linked selection, and constrained LTR dynamics. We further demonstrate chromosome-independent evolutionary patterns for both satellite-rich and LTR-rich centromeres. Collectively, these findings demonstrate how evolutionary processes drive centromere turnover and shape contrasting centromeric sequence landscapes in forest trees.

evolutionary biology↗

bioRxiv2022

Plant-on-Chip: core morphogenesis processes in the tiny plant Wolffia australiana

A plant can be thought of as a colony comprising numerous growth buds, each developing to its own rhythm. Such lack of synchrony impedes efforts to describe core principles of plant morphogenesis, dissect the underlying mechanisms, and identify regulators. Here, we use the tiniest known angiosperm to overcome this challenge and provide an ideal model system for plant morphogenesis. We present a detailed morphological description of the monocot Wolffia australiana, as well as high-quality genome information. Further, we developed the Plant-on-Chip culture system and demonstrate the application of advanced technologies such as snRNA-seq, protein structure prediction, and gene editing. We provide proof-of-concept examples that illustrate how W. australiana can open a new horizon for deciphering the core regulatory mechanisms of plant morphogenesis. SignificanceWhat is the core morphogenetic process in angiosperms, a plant like a tree indeterminately growing, or a bud sequentially generating limited types of organs? Wolffia australiana, one of the smallest angiosperms in the world may help to make a distinction. Wolffia plantlet constitutes of only three organs that are indispensable to complete life cycle: one leaf, one stamen and one gynoecium. Before the growth tip is induced to flower, it keeps branching from the leaf axil and the branches separate from the main plantlet. Here we present a high-quality genome of W. australiana, detailed morphological description, a Plant-on-Chip cultural system, and some principle-proof experiments, demonstrating that W. australiana is a promising model system for deciphering core developmental program in angiosperms.

plant biology↗