State of ex situ conservation of landrace groups of 25 major crops

Abstract

Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation.

Fig. 1. Richness map of the predicted distributions of landrace groups of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity.

Darker colours indicate greater numbers of crop landrace groups potentially overlapping in the same 2.5-arc-minute cells, quantified in terms of number of crops. See Extended Data Fig. 1 for richness across all 71 landrace groups within the 25 crops. Source data

Fig. 2. Richness maps of sorghum landrace group distributions and ex situ conservation gaps.

a,b, Predicted distributions (a) and ex situ conservation gaps (b) for five landrace groups of sorghum in Africa, South Asia, the Mediterranean, and West Asia—namely, the races bicolor, caudatum, durra, guinea and kafir. Small maps, individual distributions of each landrace group; large maps, richness at the crop level. Source data

Fig. 3. The current representation of crop landrace groups in ex situ conservation.

Conservation metrics provide a scale from the lower to the upper estimates of current ex situ conservation status per crop with the averages denoted by circles. The crop importance metric indicates the current significance of the crop, averaged across global food supply, production and trade metrics (Supplementary Information). Gold, cereals; green, pulses; purple, starchy roots/tubers/fruits. Source data

Fig. 4. Geographic hotspots for further collection for the ex situ conservation of crop landrace groups.

a, Global map of ‘gap richness’ across the predicted distributions of landrace groups of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity, indicating where landraces are expected to occur and have not yet been collected and conserved in genebanks. Darker colours indicate greater numbers of uncollected crop landrace groups potentially overlapping in the same 2.5-arc-minute cells, quantified in terms of numbers of crops. b–d, Examples of regions with particularly high gap richness in South Asia (b), the Mediterranean and West Asia (c) and Mesoamerica (d). See Extended Data Fig. 5 for gap richness across the 71 landrace groups within the 25 crops. Source data

Extended Data Fig. 1. Richness map of the predicted distributions of 71 landrace groups of 25 cereal, pulse, and starchy root/tuber/fruit crops within their geographic regions of diversity.

Richness map of the predicted distributions of 71 landrace groups of 25 cereal, pulse, and starchy root/tuber/fruit crops within their geographic regions of diversity. Darker colors indicate greater numbers of crop landrace groups potentially overlapping in the same 2.5 arc-minute cells. Source data

Extended Data Fig. 2. Richness map of the predicted distributions of landrace groups of 9 cereal crops within their geographic regions of diversity.

Richness map of the predicted distributions of landrace groups of 9 cereal crops within their geographic regions of diversity. Darker colors indicate greater numbers of crop landraces potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 3. Richness map of the predicted distributions of landrace groups of 9 pulse crops within their geographic regions of diversity.

Richness map of the predicted distributions of landrace groups of 9 pulse crops within their geographic regions of diversity. Darker colors indicate greater numbers of crop landraces potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 4. Richness map of the predicted distributions of landrace groups of 7 starchy root, tuber, and fruit crops within their geographic regions of diversity.

Richness map of the predicted distributions of landrace groups of 7 starchy root, tuber, and fruit crops within their geographic regions of diversity. Darker colors indicate greater numbers of crop landraces potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 5. Geographic hotspots for further collection for the ex situ conservation of crop landrace groups.

Geographic hotspots for further collection for the ex situ conservation of crop landrace groups. The map displays ‘gap richness’ across the predicted worldwide distributions of 71 landrace groups of 25 cereal, pulse, and starchy root/tuber/fruit crops within their geographic regions of diversity, indicating where landrace groups are expected to occur and have not yet been collected and conserved in genebanks. Darker colors indicate greater numbers of un-collected crop landrace groups potentially overlapping in the same 2.5 arc-minute cells. Source data

Extended Data Fig. 6. Geographic hotspots for further collection for the ex situ conservation of landrace groups of cereal crops.

Geographic hotspots for further collection for the ex situ conservation of landrace groups of cereal crops. The map displays ‘gap richness’ across the predicted distributions of landrace groups of 9 cereal crops within their geographic regions of diversity, indicating where landrace groups are expected to occur and have not yet been collected and conserved in genebanks. Darker colors indicate greater numbers of un-collected cereal crop landrace groups potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 7. Geographic hotspots for further collection for the ex situ conservation of landrace groups of pulse crops.

Geographic hotspots for further collection for the ex situ conservation of landrace groups of pulse crops. The map displays ‘gap richness’ across the predicted distributions of landrace groups of 9 pulse crops within their geographic regions of diversity, indicating where landrace groups are expected to occur and have not yet been collected and conserved in genebanks. Darker colors indicate greater numbers of un-collected pulse crop landrace groups potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 8. Geographic hotspots for further collection for the ex situ conservation of crop landrace groups of starchy root, tuber, and fruit crops.

Geographic hotspots for further collection for the ex situ conservation of crop landrace groups of starchy root, tuber, and fruit crops. The map displays ‘gap richness’ across the predicted distributions of landrace groups of 7 starchy root, tuber, and fruit crops within their geographic regions of diversity, indicating where landrace groups are expected to occur and have not yet been collected and conserved in genebanks. Darker colors indicate greater numbers of un-collected starchy root, tuber, and fruit crop landrace groups potentially overlapping in the same 2.5 arc-minute cells, quantified in terms of numbers of crops. Source data

Extended Data Fig. 9. Comparison of ex situ conservation representation of crop landrace groups and crop wild relative (CWR) for 25 cereal, pulse, and starchy root/tuber/fruit crops.

Comparison of ex situ conservation representation of crop landrace groups and crop wild relative (CWR) for 25 cereal, pulse, and starchy root/tuber/fruit crops. For CWR, conservation representation results were first averaged across CWR taxa in each crop genepool¹⁹. The summary results were also averaged across related crops assessed here; for example, the results for three yam crop genepools were averaged to form a single result for the global yam genepool. The crop genepool results were then transformed to the crop landrace scale and format used here, and are compared to the crop aggregated-level conservation representation average (%) estimate. Crop wild relatives of taro were not assessed in Castaneda-Alvarez et al. (2016)19; for this figure the pertinent score was set to zero. Cereals are displayed in gold, pulses in green, and starchy roots, tubers, and fruits in purple. Source data