John Anglin1, Jorge Franco2, Jose Crossa2, Susanne Dreisigacker2, and Suketoshi Taba2. (1) Clunette Elevator Co., Inc., Clunette Elevator Co., Inc., 4316 W 600 N, Leesburg, IN 46538, (2) CIMMYT, Apdo Postal 6-641, Mexico City, 06600, Mexico
Original landrace maize varieties have been replaced by modern
open pollinated varieties (OPVs) and hybrids in many places, but the elite
materials were formed using landraces as parents. Landraces may have been successful parents,
passing on many alleles to the OPVs and inbreds; they may have been poor
parents, appearing in the pedigree but contributing few useful alleles
following selection; or they may not have been used as parents at all. Knowing which landraces belong to each
category can make future breeding efforts more efficient, and guide the search
for new useful alleles. Inbred lines
created by CIMMYT have
played an important role in hybrid maize production in developing
countries. These inbreds (called CMLs)
were mainly extracted from OPVs that were themselves created by mixing many
different landraces from around the world. 209 CMLs were analysed with 22 individuals from each of 23
landraces, representative of almost all 25 major landraces from Mexico. Many were important in the formation of the CMLs. These were
analyzed with SSRs to see the contribution of each landrace to the CMLs using Structure to assign individuals to their known
population, but allowing the CMLs to vary. Results
indicate that many of the CMLs contain variation from multiple landraces, many
not represented in this study, (in agreement with their pedigrees). However, many looked like only one of the
landraces, indicating considerably less
mixing in the CIMMYT populations since their formation than expected. Landraces that were used often to form
breeding populations were found to be the most similar to the highest number of
CMLs. However, there were also some
cases of landraces that had been used often as parents whose variation are not
reflected in any of the CMLs. These may
have been poor parents, and had their variation selected out over subsequent
generations.
Handout (.pdf format, 92.0 kb)