Figure 2: Flow chart showing the breeding of the plant materials for mapping HCA1 and HCA2 and for verifying that hca1-1 and hca2-1 were sufficient to cause hybrid chlorosis in the F2 population from the cross between J147 and IR24. Arrows with a solid line indicate the flow of generation of plant materials. Arrows with a dotted line indicate the flow of information on linkage between chlorosis genes and DNA markers.