High-temperature stress susceptibility of representative japonica rice cultivars derived from Norin-22: Inadequate ATP supply during seed development may lead to severe damage

Abstract

High temperature stress during seed development can reduce the rice grain yield and lead to poor milling quality because of inadequate grain filling. We tested the high temperature stress tolerance of eight rice cultivars and fluctuations in the ATP content during seed development. The phenotype of Norin-22 was very sensitive to high temperature conditions, which decreased the grain yield and produced defective characteristics. A significant reduction in the ATP content was also detected in the developing seeds. Koshihikari and Nipponbare, which are progenies derived from Norin-22, are known to be sensitive to high temperature stress. It is suggested that the high temperature stress sensitivity of Norin-22 was inherited by these cultivars. Shinriki was tolerant of high temperature stress, and it produced a large proportion of normal-shaped grains under high temperature stress conditions, with only a moderate decrease in its ATP content. These results suggest that there was a relationship between ATP deficiency and defective endosperm characteristics. Therefore, it is expected that identifying a rice cultivar that produces an adequate amount of ATP during seed development will be useful for breeding a cultivar that tolerates high temperature stress.