Global dependence on Corn Belt Dent maize germplasm: Challenges and opportunities

Many changes affecting the management of genetic diversity occurred following recommendations made by the National Research Council in the aftermath of the Southern Leaf Corn blight epidemic of 1970-1971. New maize (Zea mays L.) breeding programs involving both publicly and privately funded collaborators were initiated. The number and scope of international maize breeding programs increased. Changes in germplasm usage included reduced usage of Lancaster Surecrop Oh43 and Mo17 types with increased use of Iodent. In contrast, continued and significant reliance upon Iowa Stiff-Stalk Synthetic (BSSS) germplasm has persisted. The availability of exotic germplasm for potential use in U.S. maize breeding has increased. However, we could find no publicly available information confirming the recent deployment of exotic germplasm on U.S. farms. Estimated global dependence upon Corn Belt Dent (CBD) germplasm is highly skewed; four countries producing 55% of global maize are 84-88% reliant on CBD. The United States and China, which collectively contribute 46% of global maize production, are 92% dependent. Trends in global usage of CBD germplasm mirror those previously seen in the United States. Concerns about genetic vulnerability that were initially addressed by the U.S. National Research Council should now be considered on a global scale.

Automated summary

Following the Southern Leaf Corn blight epidemic, the National Research Council's recommendations led to many changes in the management of genetic diversity, including the initiation of new maize breeding programs, changes in germplasm usage, and the uneven global dependence on germplasm resources. Concerns about genetic vulnerability should now be addressed on a global scale.