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Increasing Drought Tolerance in a Salt-Tolerant Japonica Rice Cultivar Using Marker-Assisted Selection
Standards used for evaluating salt-tolerance in rice seedlings. (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, and (F) whole plant nearly dead and wilted, the scale of salt-tolerance is denoted 9.
Standards used for evaluating salt-tolerance in rice seedlings. (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, and (F) whole plant nearly dead and wilted, the scale of salt-tolerance is denoted 9.

Author:I-Chun Lien, Chieh-Wei Kuo, Su-Chen Kuo, Yann-Rong Lin, and Yong-Pei Wu*

Abstract:

    Five mutant lines of Oryza sativa ssp. japonica, SM61, CWY981126, CWY981127, CWY9811268, and CNY911303, were evaluated for salt tolerance by treated with 100, 150, 200, 250, and 300 mM NaCl solutions, respectively. The CWY981126 showed the most tolerant cultivar under all concentrations except 150 mM of NaCl. On the other hand, drought tolerant cultivars were evaluated among four indica rice cultivars including ‘HY15’, ‘IR29’, ‘IR64’, and SM1 by treated with 28% PEG 6000. The ‘HY15’ showed the best tolerance to drought stress. To improve drought tolerance in the salt-tolerant japonica cultivar, the ‘HY15’ was used as a donor parent to pyramid the drought tolerant trait into the CWY981126. After two backcross generations, the drought tolerant trait was successfully introgressed into the salinity tolerant line, CWY981126. For each generation, all progenies were visually screened by drought or salinity stress tolerant phenotypes combined with a background selection using molecular markers. The recovery rates of recurrent parental genome in BC1F1, BC2F1, and BC2F2 were 73.6%, 85.5%, and 88%, respectively. Seven accessions of BC2F3 exhibited better drought tolerance than the recurrent parent, and four of them such as LD1, LD7, LD8, and LD10 also showed good salinity tolerance, indicating that these lines have dual tolerance to drought and salinity. Thus, new accessions harboring both drought and salinity tolerance were bred and could be applied to cultivate in fields with water deficiency and high salinity in Taiwan.

Key words:Marker-assisted selection, Drought tolerance, Salinity tolerance, Rice

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Journal of
Taiwan Agricultural Research
Vol. 73, No.2 (2024) ISSN: 2790-086X Vol. 73, No.2 (2024)
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