Characterization of a rice variety with high hydraulic conductance and identification of the chromosome region responsible using chromosome segment substitution lines |
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Authors: | Shunsuke Adachi Yukiko Tsuru Motohiko Kondo Toshio Yamamoto Yumiko Arai-Sanoh Tsuyu Ando Taiichiro Ookawa Masahiro Yano Tadashi Hirasawa |
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Institution: | 1Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan;2National Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan;3National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;4Institute of Society for Techno-Innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki 305-0854, Japan |
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Abstract: | Background and AimsThe rate of photosynthesis in paddy rice often decreases at noon on sunny days because of water stress, even under submerged conditions. Maintenance of higher rates of photosynthesis during the day might improve both yield and dry matter production in paddy rice. A high-yielding indica variety, ‘Habataki’, maintains a high rate of leaf photosynthesis during the daytime because of the higher hydraulic conductance from roots to leaves than in the standard japonica variety ‘Sasanishiki’. This research was conducted to characterize the trait responsible for the higher hydraulic conductance in ‘Habataki’ and identified a chromosome region for the high hydraulic conductance.MethodsHydraulic conductance to passive water transport and to osmotic water transport was determined for plants under intense transpiration and for plants without transpiration, respectively. The varietal difference in hydraulic conductance was examined with respect to root surface area and hydraulic conductivity (hydraulic conductance per root surface area, Lp). To identify the chromosome region responsible for higher hydraulic conductance, chromosome segment substitution lines (CSSLs) derived from a cross between ‘Sasanishiki’ and ‘Habataki’ were used.Key ResultsThe significantly higher hydraulic conductance resulted from the larger root surface area not from Lp in ‘Habataki’. A chromosome region associated with the elevated hydraulic conductance was detected between RM3916 and RM2431 on the long arm of chromosome 4. The CSSL, in which this region was substituted with the ‘Habataki’ chromosome segment in the ‘Sasanishiki’ background, had a larger root mass than ‘Sasanishiki’.ConclusionsThe trait for increasing plant hydraulic conductance and, therefore, maintaining the higher rate of leaf photosynthesis under the conditions of intense transpiration in ‘Habataki’ was identified, and it was estimated that there is at least one chromosome region for the trait located on chromosome 4. |
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Keywords: | Chromosome segment substitution lines diffusive conductance hydraulic conductance photosynthetic rate quantitative trait locus rice Oryza sativa root hydraulic conductivity |
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