Biology subjects

Yap, J.-Y. S.

Publications and source records attributed to Yap, J.-Y. S..

3 recordsLinked to original sources

bioRxiv2024

Genomics and resistance assays inform the management of two tree species being devastated by the invasive myrtle rust pathogen

Myrtle rust is a plant disease caused by the invasive fungal pathogen Austropuccinia psidii (G. Winter) Beenken, which has a global host list of 480 species. It was detected in Australia in 2010 and has caused the rapid decline of native Myrtaceae species, including rainforest trees Rhodamnia rubescens (Benth.) Miq. (scrub turpentine) and Rhodomyrtus psidioides (G.Don) Benth. (native guava). Ex situ collections of these species have been established, with the goal of preserving remaining genetic variation. Analysis of reduced representation sequencing (DArTseq; n = 444 for R. rubescens and n = 301 for R. psidioides) showed genetic diversity is distributed along a latitudinal gradient across the range of each species. A panel of samples of each species (n = 27 for R. rubescens and n = 37 for R. psidioides) were resequenced at genome scale, revealing large historical e]ective population sizes, and little variation among individuals in inferred levels of deleterious load. In Rhodamnia rubescens, experimental assays (n = 297) identified individuals that are putatively resistant to myrtle rust. This highlights two important points: there are tangible pathways to recovery for species that are highly susceptible to rust via a genetically informed breeding program, and there is a critical need to act quickly before more standing diversity is lost.

genomics↗

bioRxiv2024

Small but mitey: long-read assembly of a streamlined mite genome from contaminated host plant sequencing data

Technological advances have propelled DNA sequencing of non-model organisms, making sequencing more accessible and cost effective, which has also increased the availability of raw data in public repositories. However, contamination is a significant concern, and the use and reuse of sequencing data requires quality control and curation. A reference genome for the Australian native rainforest tree Rhodamnia argentea Benth. (malletwood) was assembled from Oxford Nanopore Technologies (ONT) long-reads, 10x Genomics Chromium linked-reads, and Hi-C data (N50 = 32.3 Mbp and BUSCO completeness 98.0%) with 99.0% of the 347 Mbp assembly anchored to 11 chromosomes (2n = 22). The R. argentea genome will inform conservation efforts for Myrtaceae species threatened by the global spread of the fungal disease myrtle rust. We observed contamination in the sequencing data and further investigation revealed an arthropod source. Here, we demonstrate the feasibility of assembling a high-quality gapless telomere-to-telomere mite genome using contaminated host plant sequencing data. The mite exhibits genome streamlining and has a 35 Mbp genome (68.6% BUSCO completeness) on two chromosomes, capped with a novel TTTGG telomere sequence. Phylogenomic analysis suggests that it is a previously unsequenced eriophyoid mite. Despite its unknown identity, this complete nuclear genome provides a valuable resource to investigate invertebrate genome reduction. This study emphasises the importance of checking sequencing data for contamination, especially when working with non-model organisms. It also enhances our understanding of two species, including a tree that faces substantial conservation challenges, contributing to broader biodiversity initiatives. SignificanceThe genomes of Rhodamnia argentea and an associated eriophyoid mite, which contaminated the tree raw sequencing data, were assembled for the first time. We generated valuable chromosome-level genomic resources for the conservation of myrtle rust impacted tree species, pest genomics, and understanding genome streamlining. The research underscores the growing prevalence of sequencing experiments in non-model organisms while emphasising the importance of quality control and curation of sequencing data.

genomics↗

bioRxiv2021

Chromosome-level de novo genome assembly of Telopea speciosissima (New South Wales waratah) using long-reads, linked-reads and Hi-C

Telopea speciosissima, the New South Wales waratah, is an Australian endemic woody shrub in the family Proteaceae. Waratahs have great potential as a model clade to better understand processes of speciation, introgression and adaptation, and are significant from a horticultural perspective. Here, we report the first chromosome-level genome for T. speciosissima. Combining Oxford Nanopore long-reads, 10x Genomics Chromium linked-reads and Hi-C data, the assembly spans 823 Mb (scaffold N50 of 69.0 Mb) with 97.8 % of Embryophyta BUSCOs complete. We present a new method in Diploidocus (https://github.com/slimsuite/diploidocus) for classifying, curating and QC-filtering scaffolds, which combines read depths, k-mer frequencies and BUSCO predictions. We also present a new tool, DepthSizer (https://github.com/slimsuite/depthsizer), for genome size estimation from the read depth of single copy orthologues and estimate the genome size to be approximately 900 Mb. The largest 11 scaffolds contained 94.1 % of the assembly, conforming to the expected number of chromosomes (2n = 22). Genome annotation predicted 40,158 protein-coding genes, 351 rRNAs and 728 tRNAs. We investigated CYCLOIDEA (CYC) genes, which have a role in determination of floral symmetry, and confirm the presence of two copies in the genome. Read depth analysis of 180 Duplicated BUSCO genes suggest almost all are real duplications, increasing confidence in protein family analysis using annotated protein-coding genes, and highlighting a possible need to revise the BUSCO set for this lineage. The chromosome-level T. speciosissima reference genome (Tspe_v1) provides an important new genomic resource of Proteaceae to support the conservation of flora in Australia and further afield.

genomics↗