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The Introgression of Saltol QTL into ‘TK9’ to Increase Salinity Tolerance by Using Marker-Assisted Selection
Standards used for evaluating salt-tolerance in rice seedling. (A) When plant growth is normal, the scale of salt-tolerance is denoted 0, (B) some leaves are rolled or discolored, the scale of salt-tolerance is denoted 1, (C) some leaf tips are drying, the scale of salt-tolerance is denoted 3, (D) about 1/2 leaves are drying, the scale of salt-tolerance is denoted 5, (E) about 2/3 leaves are drying, the scale of salt-tolerance is denoted 7, (F) and whole plant nearly dead and wilted, the scale of salt-tolerance is denoted 9.
Standards used for evaluating salt-tolerance in rice seedling. (A) When plant growth is normal, the scale of salt-tolerance is denoted 0, (B) some leaves are rolled or discolored, the scale of salt-tolerance is denoted 1, (C) some leaf tips are drying, the scale of salt-tolerance is denoted 3, (D) about 1/2 leaves are drying, the scale of salt-tolerance is denoted 5, (E) about 2/3 leaves are drying, the scale of salt-tolerance is denoted 7, (F) and whole plant nearly dead and wilted, the scale of salt-tolerance is denoted 9.

Author:Ning-Hsiang Wen, Chieh-Wei Kuo, Su-Chen Kuo, Yann-Rong Lin, and Yong-Pei Wu*

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 BC1F1, BC2F1, and BC2F2 generations were 71.5, 85.4, and 82.7%, respectively. In comparison with the theoretical value of traditional backcross breeding of BC2F1, 87.5%, the recurrent parent genome recovered rate of BC2F2 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 BC2F3 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 BC2F3, 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 BC2F3 with good salinity tolerance have great potential to be developed into cultivars for growing in salt affected areas in Taiwan in the future.

Key words:Marker-Assisted Selection, Salt tolerance, Rice

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Journal of
Taiwan Agricultural Research
Vol. 72, No.3 (2023) ISSN: 2790-086X Vol. 72, No.3 (2023)
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