[O31] Temperature Stress

[O31-07] Heat Resilience in Rice by Early-Morning Flowering Trait

(Invited Speaker)

^○Tsutomu Ishimaru (Division of Lowland Farming, Central Region Agricultural Research Center/National Agriculture and Food Research Organization, Japan)

Global warming is projected to have a negative impact on rice production. Reduction in grain yield due to heat-induced spikelet sterility (HISS) is one of the concerns since rice is most sensitive to heat stress at flowering. Indeed, high frequency of HISS was observed in the broad area of temperate, subtropics, and tropics in hot summer/dry season.
Shifting flower opening time (FOT) to the cooler early morning has been proposed to be effective in escaping from heat stress at flowering. Variation in FOT among modern rice varieties is very limited around 9-12AM, while there is wide variation among wild rice species. To mitigate HISS at flowering, a near-isogenic line (NIL) carrying a QTL for early-morning flowering (EMF) trait was developed by using an accession of wild rice, Oryza officinalis, as genetic resource. NIL with a background of Indica variety, IR 64, flowered 1-2 hours earlier than modern rice varieties. Multi-environmental testing with NIL for EMF is an ongoing project. Developed NIL for EMF is a unique material not only for basic study but also for the breeding program to develop the heat-resilient rice varieties. A comprehensive strategy for heat resilience in rice by early-morning flowering trait will be presented.