The latest database on world plant genetic resources highlighted that there are still large gaps, more specifically in crop wild relatives and landraces, in ex situ gene bank collections preserved across the globe . Unlike cultivated germplasm, there are difficulties associated with ex situ conservation of crop wild relatives due to their specific crop husbandry, tendency for natural pod dehiscence, seed shattering and seed dormancy, high variability in flowering and seed production, and rhizomatous nature of some of the species. Crop wild relatives have contributed many agronomically beneficial traits in shaping the modern cultivars , and they will continue to provide useful genetic variations for climate-change adaptation, and also enable crop genetic enhancers to select plants which will be well-suited for the future’s environmental conditions . There is a growing interest that crop wild relatives should be preserved in situ in protected areas to ensure the evolutionary process of wild species contributing new variants, which as and when captured by plant explorers, should be able to contribute to addressing new challenges to agricultural production . Worldwide, there are 76,000 protected areas, spread in ∼17 million km², and several countries have taken initiatives to establish crop wild relative’s in situ conservation [59-61]. Promoting in situ conservation may allow genes to evolve and respond to new environments that would be of great help to capture new genetic variants helping to mitigate climate-change impacts .
In general, plants are bred for their most obvious end products, including grain, fiber, sugar, biomass yield, fruit quality, or ornamental qualities. However, plants deployed across the landscape in agricultural or forestry settings affect the environment in measurable ways. Perennial crops have environmentally beneficial properties not present in annual crops, such as helping to prevent erosion in agricultural systems, providing wildlife habitat, and acting as sinks for carbon and nutrients. Traditionally, perennial crops have not been a major focus of breeding programs because they generally take more time and scientific knowledge to improve, and therefore, products such as new cultivars are often not produced within the timeframe of funding cycles. Current tree breeding programs are developing elms (Ulmus spp), chestnuts (Castanea dentata), hemlocks (Tsuga spp), and other species which are resistant to introduced diseases and insects [143,144]. As compared with natural selection, artificial selection via plant breeding has overcome these stresses more effectively by rapidly incorporating diverse exotic genetic sources of resistance, hybridizing to include multiple, different genetic resistances into the same plant, and making use of off-season locations or artificial conditions to shorten generation cycles. A more complex example which may be feasible in the future is tree breeding for larger and improved root systems to decrease soil erosion, sequester carbon, and improve soil quality by increasing soil organic matter.