Rice line 057 and the donor Yanhui 559 was crossed,
and then backcrossed with 057 as the recurrent parent
for four generations. During the backcrosses, agronomic
characteristics of selected plants were maintained
as similar to 057 as possible except that the low
AC trait was maintained by PCR–AccI marker-assisted
selection. After self-fertilization of the BC4F1 generation,
stable lines with low AC and good agronomic
traits were obtained. The original restorer line 057, and
the improved line were referred to as 057(GG) and
057(TT), respectively.