After such a cross, the initial plant will have genetic abnormalities. A series of crosses back to the hexaploid wheat is necessary before the desired trait from the wild species is expressed without any genetic abnormalities.
The second part of Rudd's research, working with synthetic or man-made hexaploid wheats, provides a more accessible bridge to the wild species, he said.
Most synthetic hexaploid wheats are crosses between Durum (pasta-type) wheat, which has two genomes or sets of chromosomes, and Aegilops Tauchii or goat grass, Rudd said.
The synthetic hexaploid made from this initial cross is generally wild and unuseable, except as a bridge to the wild species, he said.
"Valuable genetics are lost in the direct cross with the wild grass due to genetic abnormalities," Rudd said. "With synthetic hexaploids, the full compliment of wild relative genes is available for selection."
Researchers in Bushland and Vernon are studying synthetic hexaploids already developed through CIMMYT. Crosses between Texas winter wheat and 117 CIMMYT synthetics have already been made and another 1,100 crosses are expected to be made available to U.S. researchers, he said.
"We want to look at them for the forage characteristics they may offer, which have not been evaluated," Rudd said. "They have been shown to have large, strong seed for rapid stand establishment and early growth in the fall."
These synthetic spring wheat varieties must be backcrossed to make them winter wheats, he said. Then they can be looked at for other characteristics. "If we find something useful in the wild, we may make a synthetic hexaploid from it, or directly cross into wheat," Rudd said.
"Through traditional genetic variability we've been able to gain 1 percent a year in
Source:Texas A&M University - Agricultural Communications