Regeneration and Characterization of cultivated and wild cereal genetic resources at ICARDA [Standard Operating Procedure]

Seed regeneration is the process that leads to the generation of a new seed-lot for a given
accession with the intention to increase its stored seeds in the collection (also called
“multiplication”) or to increase the viability of its seeds equal to or above an agreed minimum
level, which is referred to as the regeneration threshold. The latter case is often termed as “seed
rejuvenation”.
Characterization is the description of plant germplasm through recording the expression of
highly heritable characters (not affected by the environment) ranging from morphological,
physiological or agronomical features to seed proteins and oil or molecular markers (FAO, 2013).
This activity provides information on traits that allows discrimination among accessions and
facilitates the verification of identity. It also includes the taxonomic identification and verification
when needed.
The Genebanks of ICARDA conserve “in-trust” a total of 76,730 accessions of small-grained
cereals belonging to 68 different taxa and originating from 110 countries (last update December
2021). The term “small-grained cereals” includes cultivated bread wheat (Triticum aestivum L.) and
durum wheat (T. turgidum Desf.), primitive tetraploid (e.g. T. dicoccon Schrank) and hexaploid wheat
(e.g. T. spelta L.), barley (Hordeum vulgare L.) and their wild relatives (Aegilops, Triticum and Hordeum).
It also includes accessions of triticale (x Triticosecale spp.), rye (Secale spp.) and oat (Avena spp). With
the exception of rye and some crop wild relatives (e.g. Aegilops speltoides, Aegilops caudata, Hordeum
bulbosum) these cereals are self-pollinated, annual and cool-season grasses. The cultivated forms are
grown for human food consumption, animal feed and forage. All of these species are found as
both, winter and facultative types (growing primarily during the winter months, requiring
vernalization to flower, and with ability to withstand prolonged periods of below freezing
temperatures) and spring types (growing primarily during the spring and summer months, normally
not requiring vernalization to flower). Details on reproductive system (self vs. cross pollination,
self-incompatibility) and on growth cycle (annual, biennial, perennial) for the most representative
small-grained cereal species maintained by ICARDA’s Genebanks are given in Annex 1.
An essential element of seed regeneration is the maintenance of genetic integrity of the original
sample. The two concerns are maintaining the occurrence of different alleles and maintaining the
frequency of these alleles. Therefore, knowledge on reproductive system, growth cycle and growth
habit of an accession are key elements for regeneration process. Cereal accessions at ICARDA are
regenerated when seed quantity falls below 1,500 seeds in medium-term storage or when seed
viability drops below 85% of initial viability of the stored seeds (75% in case of wild relative
species). Regeneration is also undertaken for the newly introduced, collected or received accessions
to allow to conduct characterization and multiply seeds to replenish active and base collection and
to send samples for safety duplication.
Planting of cereals accessions for regeneration at ICARDA is done in the months of November
and December to exploit favorable winter season precipitations and to meet the vernalization
requirements for the winter type accessions. Characterization can be carried out at any stage of the conservation process, as long as there are sufficient numbers of seeds to sample. However,
characterization of accessions at the field is done as soon as the accession will be acquired by
ICARDA’s Genebank and is often combined with the regeneration process. The GRS aims to
regenerate and characterize the accessions under conditions that meet recognized international
standards based on current technologies and scientific knowledge.
The purpose of this SOP is to give detailed instructions and to ensure consistency on the
regeneration and characterization activities of cultivated and wild cereal germplasm maintained at
ICARDA’s Genebank in compliance with national and international treaties and conventions.