A. Regarding the collection and organization of the samples

1. Streamline a protocol that not only facilitates the sample collections, but also warrants sample identification throughout the whole process (leaf collection, DNA extraction and purification, organization and storage of the DNA extracts in the bank). For the purposes of sampling, we also strongly recommend to have a stock of the following materials for your own team or any eventual collaborators:

a) zippered plastic bags with a DNA bank code. The simplest system we have devised is to print stick-on labels with the DNA bank code and stick them on the outer surface of the sampling bag, so that the sample never prevents us from seeing the code). It is useful to make 3,000 to 5,000 of these labeled bags in advance, so you don’t have to rush when there is an unforeseen collection trip.
b) silica gel for sample dessication. For an adequate drying of the leaves prior to extraction, we use a silica gel indicator, which changes colour when moisture accumulates, so you always can tell when it needs to be replaced.
c) labels and big plastic bags or newspaper sheets to organise the herbarium vouchers. Each accession at the DNA bank must have a corresponding herbarium voucher deposited at an institutional herbarium, so that the taxonomic identity of each sample can be checked if necessary. Do coordinate with the herbarium that will host the vouchers, strictly fulfilling its requirements for sample collection and labelling.
d) pre-formatted sheets to register all the information that is important to annotate during sampling in the wild.

2. If you are on the staff of (or have access to) a Botanic Garden, you can use its living and research collections to increase the resident collections of your DNA bank; only make sure you use specimens of known geographic origin and for which you can safely discard artificial hybridization (i.e., resulting from crossing with congeners growing in the Botanic Garden).

3. Build a network of collaborating taxonomists from the region the DNA bank represents and, if possible, from areas with which its present flora holds phylogeographic links. These researchers are extremely knowledgeable of the floras from their regions, they go out on field trips and collect voucher specimens regularly, and they can sample leaves for DNA isolation easily. Apart from the material we mentioned earlier, it is important to send them a leaflet with instructions to sample for DNA banking (see our lab manual) and an official letter that officially credits their important collaboration. They can also be of instrumental scientific assistance in all aspects of the research conducted with the DNA samples.

4. Build a database to keep all the information related with the DNA bank samples. This should include, at least, the specimens’ names correctly spelled out (whenever possible, use reliable thesaura), the herbarium and DNA bank codes, the geo-referenced positions of the populations, collector names, collecting locality and date, method of choice for preservation, DNA extraction process (method, volume, quality and concentration), observations (presence or absence of parasites and/or fungi on the leafs, DNA degradation, purification info, low/no volume of extracted DNA),…. Adding links to photographs of the population/plant (if you or someone in your staff sampled it), to digitalised voucher images, to the published sequences obtained with those samples or any other valuable ancillary information (papers where these samples were used, information of laboratory methods, etc...) will give your database an added scientific value.

5. Keep sufficient amounts of the dry leaves used for DNA isolation perfectly organised (if possible at -20ºC), as an insurance policy for your DNA samples, just in case re-isolations of genetic material resident at the DNA bank have to be carried out. At the moment, we keep this important material in individually labelled bags within a cold chamber within the facilities of the Molecular labs.

6. Having a curated website with information on the DNA bank stocks, downloadable sample request sheets and policy of your DNA bank for sample shipment, will allow you to offer open access to groups of research for requesting samples or collaboration.