利用分子標幟輔助導入Saltol QTL提升水稻「台稉九號」之耐鹽性

Abstract

In this study, japonica cv. 'TK9', a rice variety with high quality in Taiwan, was used as the recurrent parent and indica cv. 'Pokklali', a salt-tolerant variety with Saltol, was used as the donor parent. Marker-assisted backcross was applied to introgress Saltol QTL from 'Pokkali' to 'TK9'. For each backcross generation, the foreground selection was conducted first, and the selected progenies were subsequently subjected to background selection by marker-assisted selection. Among the backcross progeny carrying Saltol QTL, the average recovered rates of genetic background of the recurrent parent in BC_1F_1, BC_2F_1, and BC_2F_2 generations were 71.5, 85.4, and 82.7%, respectively. In comparison with the theoretical value of traditional backcross breeding of BC_2F_1, 87.5%, the recurrent parent genome recovered rate of BC_2F_2 has decreased, indicating the genetic background between parents were quite different or the condition of genetic dragging occurred. In addition, 'Pokkali', CWY981126, 'IR64', and ten lines of BC_2F_3 were treated with five concentrations of saline soution, 100, 150, 200, 250, and 300 mM of NaCl, at the fifth-leaf seedling stage. The results showed that 'Pokkali' expressed high salt-tolerance under 100, 150, and 200 mM NaCl. Moreover, STK7 and STK8, the backcross progenies of BC_2F_3, performed better salt-tolerance. Under the condition of 200 mM NaCl, STK8 had the best salt tolerance, followed by STK4 and STK7, at the fifth-leaf stage. STK7 and STK8 had best salt tolerance at active tillering stage. The Saltol QTL was successfully introgressed into 'TK9' by the evidence of salinity tolerance in the selected backcross progenies. The backcross lines of BC_2F_3 with good salinity tolerance have great potential to be developed into cultivars for growing in salt affected areas in Taiwan in the future.