CIMMYT's Asian Regional Maize Program has developed several downy mildew resistant inbred lines for use in tropical hybrid maize production in Asia. These lines, CML425-433, were released in 2001. For these CMLs, like for many CMLs released by CIMMYT, heterotic patterns (with one or more heterotic partners) via field tests of crosses to tester lines have been identified. The Asian CMLs, along with representative CMLs from the tropical, subtropical, highland, and mid-altitude maize breeding programs were analyzed with 24 simple sequence repeat (SSR) markers on polyacrylamide gel electrophoresis (PAGE) using an automatic DNA sequencer. Data were compared using a similarity coefficient and cluster analysis. For all CMLs, a total of 236 alleles were found using the 24 SSRs, with an average of 9.8 alleles per locus. Looking only at the nine Asian CMLs, 91 alleles were recorded, with an average of 3.8 alleles per locus. Cluster analysis revealed eight clusters, of which the Asian CMLs fell into only three clusters. Lines did not cluster well according to the breeding program or the source population from which they were developed, but lines closely related by pedigree did cluster together. CMLs with similar heterotic partners did cluster together in many cases, but if lines had been assigned merely to heterotic group A or B, rather than specific partners, there was no agreement with heterotic group and clustering patterns. Marker data combined with field and pedigree data may be useful to determine possible heterotic partners in the future, reducing the need for extensive field crosses.

English

0501|AGRIS 0501|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Staff Publications Collection