[O41] Genetic Improvement of Crop Yield

[O41-04] Natural Variation in Photosynthetic Induction Response in Rice (Oryza sativa L.)

*Nominated for Presentation Awards

^○Kazuki Taniyoshi, Yu Tanaka, Tatsuhiko Shiraiwa (Graduate School of Agriculture, Kyoto University, Japan)

Leaves of crop in field conditions experience fluctuating light intensity because of cloud movement and self-shading. The CO₂ assimilation rate increases gradually when leaves are subjected to sudden increases in light intensity. This process is called as photosynthetic induction response and potentially affects the crop productivity. Here, we evaluated the genetic diversity of the photosynthetic induction response among the rice diversity research set of germplasm, with two reference genotypes; Koshihikari and Takanari. Takanari is known to be a high yielding rice variety and have superior photosynthetic induction response to Koshihikari, a popular rice variety in Japan. The photosynthetic induction response showed large diversity among 59 genotypes. Cumulative CO₂ fixation during the first 10 minutes after the transition from low to high light intensity (CCF₁₀) had at most four fold differences among genotypes, from 14.2 mmol CO₂ m^-2 of ARC 11094 to 3.6 mmol CO₂ m^-2 of Koshihikari. CCF₁₀ was closely correlated with CO₂ assimilation rate and stomatal conductance just before the transition from low to high light intensity. These results indicate that the speed of photosynthetic induction response is predictable from the status of plants under low light intensity. In conclusion, the present study shows the large genetic diversity and a room of genetic improvement of the photosynthetic induction response in rice.