INTERACTIVE TOOLKIT FOR
CROP WILD RELATIVE CONSERVATION PLANNING version 1.0

CWR are defined by their potential for utilization, i.e. the ability of CWR to donate useful traits to crops. The CBD (2010) emphasizes the need to link conservation to use, noting that utilization should be "sustainable" and "meet the needs and aspirations of present and future generations". Maxted and Kell (2009) reviewed the use of CWR in crop improvement for 29 major crops and noted the following points:

• For the 29 major crops studied there were 234 references that report the identification of useful traits from 183 CWR taxa.
• The degree to which breeders use CWR species varies between crops. Use is particularly prominent in barley, cassava, potato, rice, tomato and wheat, but rice and wheat are the crops for which CWR have been most widely used, both in terms of number of CWR taxa used and successful attempts to introgress traits from the CWR to the crop.
• The most widespread CWR use has been, and remains, in the development of disease and pest resistance, with the references citing disease resistance objectives accounting for 39% of all references for the 29 major crops. Pest and disease resistance accounts for 17%, abiotic stress 13%, yield increase 10%, cytoplasmic male sterility and fertility restorers 4%, quality improvers 11% and husbandry improvement 6% of the reported inter-specific trait transfers.
• The number of paper publications detailing use of CWR in breeding has increased gradually over time, presumably as a result of technological developments for trait transfer. Two percent of citations were recorded prior to 1970, 13% in the 1970s, 15% in the 1980s, 32% in the 1990s and 38% after 1999.
• Since the year 2000 the number of attempts to improve quality, husbandry and end-product commodities has increased substantially.
• The use of CWR in crop improvement was primarily based upon published journal papers, but this is unlikely to be a close reflection of the actual use of CWR in commercial crop breeding because: (a) the reporting of a useful trait transfer from a CWR to a crop does not mean that it has resulted in a novel variety and (b) breeders are unlikely to be forthcoming about their use of CWR due commercially sensitive issues. Therefore, the use of CWR in crop improvement is significant but imprecisely defined.
• The use of the potential diversity contained in CWR species remains ad hoc, as CWR use by breeders has not been systematic or comprehensive.

The review concludes that there is a wealth of novel traits available for crop improvement in CWR and so far the vast majority of CWR diversity is untapped in terms of its potential utilization value. Also see Some examples of CWR use in crop improvement  [2].

There are numerous ways in which the use of CWR diversity for crop improvement can be promoted, but traditionally this has focused on identifying traits of interest through phenotypic characterization and evaluation. However, in many cases this has proved prohibitively expensive. The First SoW Report (FAO 1998) highlights the fact that two thirds of globally conserved ex situ germplasm lacks basic passport data, 80% lacks characterization data and 95% lacks evaluation data, making the use of such germplasm—including CWR germplasm—much more difficult than it need be. The SoWPGR-2 (FAO 2010) details several new international initiatives since 1998 that support the increased characterization and evaluation of germplasm, including the fairly widespread adoption of core collections that are adequately characterized and evaluated. However, it still concludes that “the country reports were virtually unanimous in suggesting that one of the most significant obstacles to a greater use of PGRFA is the lack of adequate characterization and evaluation data and the capacity to generate and manage such data”.

The bottleneck of systematic characterization and evaluation has been acknowledged almost since the late 1960s and early 1970s when the need for their conservation was recognized (Frankel and Bennett, 1970). It could be argued that simply increasing the amount of ‘traditional’ characterization and evaluation is unlikely to result in the required step change in the exploitation of CWR diversity. However, novel techniques such as ‘next generation technologies’—that enable the screening of thousands of samples of germplasm for interesting gene variants that are adaptively important (Nordborg and Weigel 2008)—and ‘predictive characterization’—where spatial analysis of germplasm passport data is used to predict which germplasm accessions might have desired traits (see Bhullar et al. 2009, Thormann et al. 2014)—offer an alternative to conventional characterization and evaluation. Ultimately, the use of conserved CWR (and indeed of all PGRFA) diversity is not likely to improve unless the professionals involved with CWR conservation can ensure that conserved germplasm is more accessible to breeders and other user groups, removing the barrier between conservation and use.