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Climate change is widely acknowledged to have severe implications for global food production and therefore food security. Utilising crop wild relatives (CWR) to help build resilience in domesticated crops is seen as part of the solution assuming that important genetic traits can be transferred to domesticated crops and that the resulting improved crop varieties can be farmed on a sufficiently large scale. CWR can be exploited as a valuable source of alleles related to adaptive traits to counter abiotic and biotic stresses resulting from climate change, and to improve yield and nutrition. This review aims to critically analyse the degree to which CWR have been utilised by crop breeders and researchers and will draw conclusions about the importance of CWR in preparing agriculture for climate change. Examples for CWR-derived improved varieties of nine major crops and at different plant development stages are presented. However, working with CWR is often seen as ‘marginal’. It is problematic due to the complex processes involved and length of time needed for traditional crop breeding, shortage of funds, the limited availability of CWR germplasm, overcoming risk aversion among farmers, and a reluctance by the wider agricultural community to appreciate the scale of the problem and to embrace the potential benefits that could derive from using CWR in crop breeding. Given the observed lack of availability of CWR in accessible germplasm collections, additional resources must be directed towards ensuring CWR are protected in situ and conserved ex situ so they can be made available to researchers.

Most propagule bank research has been conducted in rural areas and has emphasised agricultural soils, although research on rural riparian propagule banks has expanded rapidly over the last decade. This paper presents observations of the species abundance of plant propagules in urban riparian soils along the River Brent, Greater London, UK. The data are analysed to explore changes in species abundance of the propagule bank with depth (0–5 cm compared with 5–10 cm soil layer), with distance from the river (0–1 m, 1–2 m, 2–3 m), and at different locations on the river network. No significant differences were found in propagule abundance with soil depth or distance from the river’s edge, but significantly more species were found in the propagule bank close to the river’s edge. The species composition of the Brent’s propagule bank is then compared with riparian propagule banks from the rural rivers Dove, Frome and Tern, UK. Species richness of the Brent propagule bank samples was generally lower than was found in the three rural rivers and, in total, 21%, 4%, 5% and 4% of observed species were aliens in the Brent, Dove, Frome and Tern soil samples, respectively. When the species present in the Brent’s propagule bank were compared with published data on urban garden soils in another UK city, the latter were found to support a higher number of alien species, suggesting that other propagule sources to urban river systems support lower numbers of alien species in riparian zones than domestic gardens.

Impatiens glandulifera was first thought to be a highly desirable addition to English gardens. In general, the early recognition of an undesirable/potentially invasive species is rare and often takes decades (Williamson, 1996) and this was most certainly the case with I. glandulifera. This may be due to a lag phase associated with the invasive nature of some plants, where initially the population expansion is slow while the species adapts to the new environment; subsequently, this is followed by the exponential phase that sees arapid explosion in the spread and occurrence of the species. The rate at which a species spreads is likely to be as much related to human activity (Perrings et al, 2002) and landscape factors, as it is to the biology and ecology of the species (Williamson et al, 2005). I. glandulifera has found its ideal conditions predominantly along the rivers of Europe and elsewhere, aided by the explosive release of its seeds coupled with hydrochorous dispersal. There is also evidence thatI. glandulifera is capable of invading disturbed deciduous woodland and ungrazed tall herb/ruderal/ grassland habitats (e.g. Maskell et al, 2006; Andrews et al, 2009) as a result of human-assisted transportation of seed material in soil, by beekeepers and accidental release in garden waste and on vehicles (Kowarik, 2003).