Trans Situ Conservation of Crop Wild Relatives

In the face of unprecedented climatic disasters, social conflict, and political uncertainty, integrating in situ and ex situ strategies may become increasingly necessary to effectively conserve crop wild relatives (CWR). We introduce the concept of trans situ conservation to safeguard CWR genetic diversity and accessibility for crop improvement. Building on initiatives to combine in situ protection with ex situ backup in genebanks, trans situ conservation dynamically integrates multiple in situ and ex situ measures, from conservation to research to education, spanning local to global scales. Two important features emerge from a trans situ approach. First, integrating in situ and ex situ studies of CWR genetic diversity, adaptation, and ecological interactions can lead to advances in crop improvement and in situ management. Second, the complementarity, redundancy, and synergy gained through trans situ conservation buffer climatic, economic, political, and institutional instabilities. Focusing on a case study in the United States–Mexico desert borderlands, we evaluate three components of trans situ conservation: in situ protection on working and public lands; seed and living plant collections in local and regional botanical gardens, arboreta, and nurseries; and genebank accessions in the USDA National Plant Germplasm System. We discuss gaps, tensions, and synergies that emerge when coordinating these three components and offer the conservation of the wild chile [ Capsicum annuum L. var. glabriusculum (Dunal) Heiser & Pickersgill] in southern Arizona as an example of concerted in situ and ex situ research integrated in a trans situ framework