Sanger Tree of Life HMW DNA Extraction: Automated Plant MagAttract v.1

Caroline Howard, graeme oatley, Michelle Strickland, Maja Todorovic, Filipa Sampaio, Edel Sheerin

Published: 2023-09-30 DOI: 10.17504/protocols.io.n2bvj3n1xlk5/v1

Abstract

This protocol describes the automated extraction of HMW DNA from cryogenically disrupted plant and fungi tissue samples intended for long-read sequencing. It employs the Qiagen MagAttract HMW DNA extraction kit and the Thermo Fisher KingFisher™ Apex. This process is effective for a wide variety of plant species covered by the Tree of Life Programme. The output of this protocol is HMW DNA, which depending upon yield and genome size of the species, can be directed towards either HMW DNA Pooling or HMW DNA Fragmentation: Diagenode Megaruptor®3 for LI HiFi. This protocol was adapted from Sanger Tree of Life HMW DNA Extraction: Manual Plant MagAttract v.1 to include automation for a higher throughput of samples, and was updated to Sanger Tree of Life HMW DNA Extraction: Automated Plant MagAttract v.2 to improve sample lysis.

Acronyms

HMW: high molecular weight

SPRI: solid-phase reversible immobilisation

HiFi: high fidelity

Before start

Add 100% ethanol to MW1 and PE wash buffers as per manufacturer’s instructions.

Steps

Sample lysis

1.

Prepare a lysis buffer master mix:

AB
Phosphate-buffered saline (PBS)200 µL
Proteinase K20 µL
RNase A4 µL
Buffer AL150 µL
2.

Set a heat block to 50 °C.

3.

Transfer 50 mg of cryogenically homogenised tissue from each sample to 2 mL microcentrifuge tubes and place on dry ice to keep the samples frozen.

4.

Add 374 µL of the lysis buffer master mix to each sample, then homogenise sample and mastermix by gently pipetting 10 times with a wide-bore pipette tip.

5.

Centrifuge tube briefly to collect, then incubate on the heat block at 50 °C for 2 hours.

Loading and Running the KingFisher™ Apex

6.

While samples are lysing, label nine 1 mL 96-well deep-well KingFisher™ plates and fill the number of wells required for the number of samples in each plate as follows:

AB
Tip plate96-well tip comb (no reagent)
Elution 2200 µL Buffer AE
Elution 1200 µL Buffer AE
NFW Wash500 µL Nuclease-free water
PE Wash 2700 µL Buffer PE
PE Wash 1700 µL Buffer PE
MW1 Wash 2700 µL Buffer MW1
MW1 Wash 1700 µL Buffer MW1
Sample plate15 µL Suspension G magnetic beads 280 µL Buffer MB
7.

Once samples have completed lysing, remove sample tubes from the heat block and briefly centrifuge to spin down.

8.

Using a wide-bore pipette tip, set the volume to 380 µL, transfer lysate from the sample tubes to individual wells in the sample plate, taking care not to transfer large pieces of debris if possible.

9.

Select the required protocol in the protocol list on the KingFisher™ Apex (details in KingFisher™ Apex DNA Extraction Protocol Script/attached KFX file in the Materials section) and select using the play button.

10.

Load the filled plates onto the instrument following the instructions provided on screen.

11.

Prior to loading the “Sample Plate”, the instrument will prompt to remove the “Tip Plate”. Once the final plate is loaded, the protocol will automatically begin; this takes approximately 50 minutes.

12.

Once the protocol has completed, follow the on-screen instructions to remove plates from the instrument.

13.

Inspect the elution plates for any magnetic beads in the wells. In the rare instance of magnetic beads remaining in the eluate (possible in viscous samples), these samples will need to be transferred to a 1.5 mL microcentrifuge tube and placed on a magnetic rack. Allow around 5 minutes for the beads to migrate and take the clear eluate containing the DNA using a wide-bore pipette tip.

14.

Using a 200 µL multi-channel pipette and wide-bore tips, pipette eluates from the elution plate into microcentrifuge tubes, pipette mix with wide-bore tips to fully homogenise DNA in the eluate.

15.

Perform required QC and then store the DNA at 4 °C.

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