A STUDY OF GENETIC CONTROL OF ADULT PLANT RESISTANCE IN SUBTERRANEAN CLOVER TO TWO RACES OF KABATIELLA CAULIVORA
MJ BARBETTI, P SI and PGH NICHOLS
Agriculture Western Australia, 3 Baron-Hay Court, South Perth, Western Australia 6151, Australia; Centre For Legumes In Mediterranean Agriculture, University Of Western Australia, Mounts Bay Road, Nediands, Western Australia 6009, Australia
Background and objectives
Results and conclusions
Diallel analysis showed that the genetic control for resistance to both races was governed by simple additive and dominant gene effects. Regression analysis indicated an absence of non-allelic gene interactions and the presence of partial dominance.
For the old race, Daliak, Denmark and Meteora showed dominant gene effects for resistance. This is consistent with the results of Beale and Thurling  for ssp. yanninnicum. Goulburn, however, showed recessive gene effects for resistance. The most susceptible parent, Woogeneflup, had recessive genes for susceptibility, while Karridale and Mt Barker showed intermediate gene effects. For the new race, resistance was controlled by dominant genes in Denmark, with Goulburn showing recessive gene effects. Daliak and Mt Barker showed recessive gene effects for susceptibility. However, Meteora, Karridale and Woogenellup showed intermediate effects.
The number of genes controlling resistance to the old race was determined in three crosses between a resistant cultivar (Daliak, Meteora, or Denmark) and the susceptible Woogenellup. F2 plants were examined for their segregation ratios. Daliak and Meteora both had one completely dominant gene governing resistance. However, the resistance in Denmark was controlled by two genes with complete dominance, which may explain its resistance to both races in the field.
Incorporating multiple gene resistance to Kabatielia into a range of subterranean clover cultivars is now a major subterranean clover breeding objective, in order to provide more durable resistance.