A crop wild relative (CWR) is a wild plant that is closely connected to a plant that people grow. It could be the wild ancestor of the grown plant or a different type of plant that is closely related.

Overview

Crop wild relatives (CWRs) are becoming an important resource for improving farming and keeping ecosystems healthy. In nature, these plants develop traits that can be passed to crops through breeding. As human-caused climate change and unstable ecosystems grow, CWRs may be essential for keeping food supplies safe in the future. In the early 1900s, Russian scientist Nikolai Vavilov recognized the value of CWRs. For thousands of years, humans have used genetic material from CWRs to improve crops. Farmers have long used traditional breeding methods, such as growing wild maize (Zea mexicana) near cultivated maize to encourage natural crossbreeding and increase yields. Recently, plant breeders have used genes from CWRs to improve crops like rice (Oryza sativa), tomato (Solanum lycopersicum), and grain legumes.

CWRs have given many useful genes to crops, and most major crop varieties today include genes from their wild relatives. CWRs are wild plants related to species important for food, animal feed, medicine, decoration, and industry, such as plants used for oils and fibers. These plants can provide helpful traits to crops. A CWR is defined as "a wild plant species that has indirect value because of its close genetic connection to a crop."

Conservation of crop wild relatives

Crop Wild Relatives (CWRs) are important parts of natural and farming ecosystems. They are necessary for keeping ecosystems healthy. Protecting and using CWRs wisely helps improve farming, increase food supplies, and keep the environment healthy.

Many CWRs are at risk because their natural homes are being destroyed or changed for other uses. Trees are being cut down, which harms wild relatives of fruit, nut, and industrial crops. Wild relatives of cereal crops in dry areas are losing their populations due to overgrazing, which causes land to become dry and barren. As farming becomes more industrialized, CWRs are disappearing from traditional farming areas. Protecting and using CWRs wisely is important for improving food supplies, reducing poverty, and keeping the environment healthy.

Ways to conserve CWRs include protecting them in their natural habitats and storing their seeds in special places. These methods work together because each has strengths and weaknesses. For example, storing seeds in special places protects them from dangers in the wild, but this method might not help them adapt to new challenges.

In 2016, 29% of wild relative plant species were not found in global seed collections. Another 24% had fewer than 10 samples stored. Over 70% of all CWR species needed more samples to be fully represented in seed collections. More than 95% of CWR species were not well represented in terms of where they naturally live and the different environments they grow in. The most urgent need for collecting was in areas like the Mediterranean and Near East, Western and Southern Europe, Southeast and East Asia, and South America. However, CWRs that are not well represented in seed collections are found in nearly every country around the world.

Examples of wild relatives

• Oats (Avena sativa) – Avena byzantina
• Quinoa (Chenopodium quinoa) – Chenopodium berlandieri
• Finger Millet (Eleusine coracana) – Eleusine africana
• Barley (Hordeum vulgare) – Hordeum arizonicum and Hordeum spontaneum
• Rice (Oryza sativa) – Oryza rufipogon
• African Rice (Oryza glaberrima) – Oryza barthii
• Pearl Millet (Pennisetum glaucum) – Pennisetum purpureum
• Rye (Secale cereale subsp. cereale) – Secale cereale subsp. dighoricum
• Sorghum (Sorghum bicolor) – Sorghum arundinaceum and Sorghum halepense
• Broom millet (Panicum miliaceum) – Panicum fauriei
• Wheat (Triticum aestivum) – Einkorn wheat (Triticum monococcum)
• Maize (Zea mays subsp. mays) – Zea diploperennis

Note: Many vegetables share a common ancestor, especially in the Brassica genus. Some vegetables are hybrids of different species, which is common among Brassicas.

• Asparagus (Asparagus officinalis) – Asparagus dauricus
• Beet (Beta vulgaris subsp. vulgaris) – Beta vulgaris subsp. maritima
• Black Mustard (Brassica nigra) – Wild mustard (Sinapis arvensis)
• Cabbage (Brassica oleracea var. capitata) – Brassica elongata
• Carrot (Daucus carota) – Daucus gracilis
• Garlic (Allium sativum var. sativum) – Allium atroviolaceum
• Leek (Allium ampeloprasum) – Welsh onion (Allium fistulosum)
• Lettuce (Lactuca sativa) – Prickly lettuce (Lactuca serriola)
• Mustard (Brassica juncea subsp. juncea) – Brassica carinata
• Onion (Allium cepa var. cepa) – Allium galanthum
• Rape (Brassica napus var. napus) – Common dogmustard (Erucastrum gallicum)
• Spinach (Spinacea oleracea) – Spinacia turkestanica
• Squash (Cucurbita pepo subsp. pepo) – Cucurbita okeechobeensis
• Turnip (Brassica rapa subsp. rapa) – Brassica rapa

• Almond (Prunus dulcis) – Chinese plum (Prunus salicina and others)
• Apple (Malus domestica) – Mostly Malus sieversii, with some cultivars possibly from Malus sylvestris or hybrids of the two
• Apricot (Prunus armeniaca) – Prunus brigantina
• Avocado (Persea americana) – Persea schiedeana
• Banana – Musa acuminata, Musa balbisiana, and Musa schizocarpa
• Breadfruit (Artocarpus altilis) – Jackfruit (Artocarpus heterophyllus)
• Cacao (Theobroma cacao) – Theobroma angustifolium
• Cherry (Prunus avium) – Prunus mahaleb
• Cucumber (Cucumis sativus) – Cucumis hystrix
• Eggplant (Solanum melongena) – Thorn apple (Solanum incanum), Solanum insanum
• Grape (Vitis vinifera) – European wild grape (Vitis sylvestris). Hybrids also exist with other Vitis species
• Grapefruit (Citrus paradisi) – Citrus medica
• Lemon (Citrus limon) – Citrus indica
• Mango (Mangifera indica) – Mangifera altissima
• Orange (Citrus sinensis) – Key lime (Citrus aurantiifolia)
• Papaya (Carica papaya) – Jarilla chocola
• Peach (Prunus persica var. persica) – Prunus tomentosa
• Pear (Pyrus communis) – Pyrus pyraster and Pyrus caucasica
• Pepper (Capsicum annuum) – Capsicum baccatum
• Pineapple (Ananas comosus) – Ananas bracteatus
• Plum (Prunus domestica subsp. domestica) – Prunus spinosa and Prunus cerasifera
• Pumpkin (Cucurbita maxima subsp. maxima) – Cucurbita ecuadorensis
• Strawberry (Fragaria × ananassa)
• Tomato (Solanum lycopersicum) – Solanum chilense
• Watermelon (Citrullus lanatus var. lanatus) – Bitter apple (Citrullus colocynthis)

• Peanut (Arachis hypogaea subsp. hypogaea) – Arachis duranensis
• Sunflower (Helianthus annuus) – Helianthus exilis
• Soya (Glycine max) – Glycine clandestina
• Safflower (Carthamus tinctorius) – Carthamus creticus
• Rapeseed (Brassica napus) – Brassica rapa, Brassica oleracea

• Lentil (Lens culinaris) – Lens ervoides
• Garden Pea (Pisum sativum) – Pisum fulvum
• Butter Bean (Phaseolus lunatus) – Phaseolus augusti
• Garden Bean (Phaseolus vulgaris) – Phaseolus coccineus
• Faba Bean (Vicia faba) – Vicia johannis
• Grasspea (Lathyrus sativus) – Lathyrus tuberosus
• Cowpea (Vigna unguiculata) – Vigna monantha
• Bambara groundnut