GB-London: RBGKEW1276 - Whole Genome Sequencing for cacao DNA from herbarium specimens

The Royal Botanic Gardens, Kew (RBG Kew) intends to appoint a supplier for a high-throughput sequencing service from ancient-DNA extractions sourced from historical herbarium collections of cacao specimens (Theobroma cacao, Malvaceae) and wild relative species (Theobroma/Herrania spp.).

Utilizing a CTAB-extraction method, the extracted samples will be sent in batches.

The supplier must conduct pre-quality control (QC) tests (including RNase treatment and DNA purification, if necessary) on these total-genome DNA extractions, ensuring acceptable yields and concentrations.

Tasks also include library preparation using the Nextera XT Library Kit and performing paired-end whole genomic sequencing (WGS) using the Illumina NovaSeq 6000 (or an equally powerful sequencing platform) to seek obtaining ideally ~12 Gb per sample, depending on the conditions of the sample.

This process aims to cover 120-140 samples, targeting a coverage of 15-30x each, given the known genome size of Theobroma species at ~450-490 Mbp.

The supplier should be acquainted with high-throughput sequencing from aged herbarium samples, due to the historical nature of these collections (preserved over 50-100 years ago).

They are expected to have previous experience in the production of satisfactory data under these conditions and will need to state this in the application.

Each sample sent will contain 25-50 uL of DNA, predominantly at concentrations of 10 ng/uL (some with less, but never less than 0.5 ng/uL of total DNA).

It is expected that many samples will have heavily fragmented DNA, and the supplier should be able to present alternatives to deal with these.

Following sequencing, the supplier should conduct post-QC to verify data quality before delivery.

Data transfer methods such as USB, HDD, or preferably Cloud transfer are viable options.

The genomic data obtained will support an ongoing project at RBG Kew.

This project aims to comprehensively study the geographical history, and other population genomic studies of Theobroma cacao at a global scale, utilising molecular data obtained from historical herbarium collections combined with data obtained from other sources.