Universidad
Politécnica de Madrid

Santiago Moreno, full professor of the Plant Biotechnology- Biology Department, has recently taken on the task of leading the UPM Plant Germplasm Bank (UPM-PGB). He mentions two essential functions in this facility, located in the Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas (ETSIAAB). First, preserving biodiversity, as "basis for good ecosystem status". Secondly, promoting scientific advances "for a better understanding of plant genetic resources and a more sustainable development of food and agriculture". Furthermore, Professor Moreno reminds the connection of these tasks with two of the Sustainable Development Goals (SDGs) promoted by the UN: Protect, restore and promote terrestrial ecosystems and, end hunger.

The importance of the UPM-PGB begins with its historic nature. It was the first in the world to specialise in wild seeds.

Indeed, it was born in 1966, with Cruciferae family wild plants that Professor César Gómez Campo used as a basis for his research work. Its creation comes at the years of excellent plant breeding developments, on what was termed the green revolution. By that time, there already was interest in conserving seeds of cultivated species; in fact, several banks had been created for this purpose in the world. When Professor Gómez Campo made the world's first seed bank for wild species, he was not only recognising the intrinsic value of wild species seeds but also their potential application for crop breeding.

What are the most relevant collections? How many species does the bank keep?

Wild crucifers are, for sure the most internationally recognised collection. Not only cabbages, radishes, turnips and mustard belong to this family but also an endless number of wild species, including Diplotaxis (wall-rocket) that portrays our fields and cities yellow in early spring. The UPM-PGB gathers one of the vastest collections of wild crucifers worldwide with almost 500 species and more than 1,500 accessions. Because of their kinship with the cultivated species mentioned above, many of these species have a particular added value. There is also a well-known second collection of endemic species from the Iberian Peninsula, the Balearic Islands and the Macaronesian region, which includes the Canary Islands archipelago. The Artemis project allowed the implementation of this collection a few years later, in 1973. Its purpose was to collect and conserve the seeds of our endemic species in the long term. Nowadays around 300 endemic species in all are conserved in the bank.

Are the incorporations still ongoing, or is it a closed inventory?

Although budget and staff cuts affect incorporations, these keep on due to two key reasons. First, there is still a lot of exciting material not present in the UPM-PGB. For example, the representation of species of the Cruciferae family is impressive, but the representation of the different populations that frame each species is not so good. This issue becomes vital as breeders [focused on getting varieties with characteristics superior to those already existing] can sometimes find genes of interest in the intraspecific variability of wild material.

Secondly, the bank, as a member of the Collection Network of the National Programme of Plant Genetic Resources, cooperates honouring the international commitments our country has undertaken in terms of plant genetic resources conservation and global management for food and agriculture. Besides, concerning wild material, the Bank also has responsibilities as a member of Redbag [Red Española de Bancos de Germoplasma de Plantas Silvestres y Fitorrecursos] and Ensconet [European native seed conservation network]. In consequence, both nationally and internationally, concerning both wild and crops, we are required, under specific procedures, to provide material for in situ conservation support tasks and for scientific studies too. The outflow of material from a bank together with no inflow at the end decapitalise the Bank; this must not be allowed to happen. Last entries from this year come from a Biosphere Reserve in Madrid named Sierra del Rincón: germplasm of 15 species, all crop wild relatives.

How to keep the seeds for such a long time?

There is some tiny but significant metabolic activity in every living seed. At large, the reason why a seed ends up dying is not that its food reserves are depleted, but because products of its metabolism are accumulated within the seed itself and finally intoxicate it. Therefore, the key to preserving seeds is to slow down metabolic activity as much as possible. In seeds from temperate areas, it is usually achieved by lowering humidity and temperature at which seeds are conserved. Because of this, our Bank keeps the seeds, as most banks do, in a cold chamber with a system for evacuating humidity.

Professor Gómez Campo was aware that humidity was the critical factor of these two parameters. He strived for finding a completely airtight container for the seeds for many years. It would completely prevent ambient humidity entry once seeds had been dried and packed. At last, he found it: a melt-closed glass container; inside, a drying agent indicating packaging defects, silica gel, next to the seeds. This system has been proven to be entirely practical fifty years after the first seed encapsulations. It has been a model for many banks worldwide.

What are the UPM-PGB’s tasks?

On the one hand, seed banks take special care to preserve endangered species seeds in their natural environments. We conserve 20% of Spain's endangered flora. Thus, the UPM is making a significant contribution, helping Spain to fulfil its commitments as a signatory to the Convention on Biological Diversity. The bank has also joined in programmes to restore species disappeared from nature. The reintroduction of Diplotaxis siettiana, a species endemic to Alboran Island which became extinct is the most symbolic example. Despite the importance of the above, it is also essential to bear in mind that banks are committed to ex situ conservation of material that is not critically endangered, even in a good state of in situ conservation. The goal is counting on some backup in case the in situ conservation status deteriorates. This situation is not a figment of our imagination; it is taking place due to climate change, and it is happening fast.

On the other hand, banks promote basic or applied scientific studies on plant species. Scientists do not have to collect species seeds in the field for their research; they directly seek them from the bank. It is worth stressing the germplasm banks role as genes source for crop breeding programmes, among the applied studies. The obtention of ‘superbroccoli’ Beneforte was one of the most paradigmatic examples; It contains extraordinarily high levels of a glucosinolate that helps in cancer prevention; Its breeding programme utilised material (Brassica villosa) from the UPM-PGB.

At the UPM-PGB, the seed bank is the nucleus; however, there is also an in vitro conservation unit and two facilities for practical courses and dissemination activities.

Indeed. Although the in vitro collection is very short when compared to others, its material is considerable due to its rarity or threat. Therefore, species for which seed conservation has drawbacks are maintained, as in the case of Borderea chouardii, Narcissus cavanillesii, etc. In vitro growth slowed down by low temperatures and modification of the culture medium components is used to preserve the material. In addition, two dissemination field resources are located at the agricultural experimentation fields at the ETSIAAB. Four Mediterranean ecosystems are recreated in the Mediterranean Botanic Garden, in just over 6,000 square metres, with their dominant species: cork oak forest, gall oak-ash forest, holm oak forest and kermes oak-savin forest. There is a collection of more than 200 plant species from around the world in the Greenhouse-Classroom; some of the most endangered Spanish endemisms, such as Vella psedocytisus, Silene hifacensis, Lisimaquia minoricensis are kept inside. The first one, an odd shrubby cruciferous, probably one of the most outstanding elements of the endemic flora of Madrid region.

RESEARCH REGARDING THE UPM-PGB

The UPM-PGB is part of the Biotechnology-Plant Biology Department, which makes the research work around this bond intense and continuous. Santiago Moreno, as its new director, indicates, by way of example, that two other lines of study have recently been started. The first deals with "the possible use of wild Brassica oleracea in chemoprotective diets against cancer". The ETSIAAB Professor explains that this cruciferous plant, "has the peculiarity of including both cultivated material (cabbages, kale, cauliflower, broccoli) and wild material". In the second one, "the nutritional values of the microgreens or baby greens (edible seedlings) of wild crucifers are being analysed".

Asking questions is an essential aspect of the scientific method for advancing knowledge; Maybe because that is the teacher in him, Dr. Moreno asks some questions about the review about research activity in the bank, starting with his thought. "There is a primary research task aiming to answer a logical question: is what preserved in the bank representative of what exists in nature? To answer this question, not only the morphology of seeds and plants to which they give rise is analysed, but also their DNA", which enables to analyse "diversity within the species, diversity amongst populations and within populations".

"When it comes to wild material, it is crucial to know the coordinates of the place where the material was collected to enhance and consolidate information provided by morphology and DNA" explains the head of the Bank. "It is possible to know, thanks to these coordinates and through geographic information systems, many aspects regarding the environment in which live the plants that provided us with the seeds. If a species can live, let us say, ten different environment types, our seed collection in the Bank can only be representative if it contains seed samples from most of the environments above."

Professor Moreno explains that "It has been less than ten years since three researchers involved in the bank developed protocols for eco-geographical evaluation of germplasm collections with these purposes: Detect gaps, create nuclear collections (without duplicates) and rationalise recollections (to cover gaps)". "Today many European and South American institutions use these procedures," he says with delight.

The Bank has worked towards another key aspect: maintenance of the material. "The essential issue now is: what are the conservation techniques that most prolong seed viability and least alter genetic and epigenetic stability?” The Professor explains that "Considering two key parameters, humidity and temperature, Professor César Gómez Campo, the Bank's founder, improved very long term conservation techniques by focusing on humidity. However, there are other questions that keep being asked. How far can a seed be cooled? Is it possible to use liquid nitrogen to preserve seeds? What is the optimum desiccation level?  What can be done with seeds that do not tolerate desiccation? To what extent seeds ageing in a germplasm bank alter genetically or epigenetically their DNA?

The listing of interrogations keeps on. "When it comes to face a given seed lot, a common question in any genebank would be: are they viable? Germination tests must be undertaken to answer this question; however, when they start germinating, viable seeds do not germinate for sure because they have mechanisms that prevent or slow down germination. Seed germination study has been a recurring research issue in our bank, and continues to be," says Dr. Moreno.

The Professor states that the researcher's interest has also focused on the wild relatives of crops in recent years. Once again, a question arises: what can they offer to meet the challenge that climate change poses to current crops? The answer, he says, is simple: resilience to alterations "resulting from the hydrological cycle intensification (major droughts, heavy rainfall) caused by global warming". Dr. Moreno explains that the Bank is, on the one hand, extending this type of material and, on the other, characterising in an eco-geographical way. "The hypotheses could be, for instance, that species germplasm collected in arid areas provides water scarcity resilience and that species germplasm collected in warmer areas provides more significant temperature rise adaptation ".

Nevertheless, even if this were indeed the case "how can that be applied to crops better-adapted to climate change? he asks. "There are two paths, and the role played by technology is crucial". The first one using genomics, the bigdata of the genome, to support the classical process gene introgression from wild material into cultivated material. The second one, by de novo domestication of the wild relatives of the crops utilising high-precision biotechnology techniques such as genome editing".

Finally, Dr Moreno almost begs "one last note on this", "The contrast between the wild and the cultivated by means of pangenomic studies (comparison of multiple genomes of the same species or taxon) will help to understand the genetic keys to the resilience of wild material that have been lost in the process of domestication. Biotechnology has undoubtedly increased the value of germplasm banks in general, and particularly of those specialised in wild germplasm".