Abstract:

The utilization of heterosis between indica and japonica rice is an important approach to improve the productivity of rice. However, the reduced productivity due to the influence of abnormal temperature on spikelet sterility has been limiting the application of the indica-japonica cross of rice. The objective of this study was to identify the quantitative traits loci (QTLs) related to the spikelet fertility of the indica-japonica cross of rice under high growth temperature. The backcross population of USSR5/ Guangjie 9//USSR5 and related molecular map were constructed. The spikelet fertility under high temperature and heat susceptibility index (HSI) of spikelet fertility were used to evaluate the tolerance of rice to heat stress at booting stage, respectively. These QTLs related to heat tolerance at the booting stage were detected on chromosome 2, 4 and 5, respectively, which explained 6.4%–15.8% of the observed phenotypic variance. Two QTLs related to relative heat tolerance at the booting stage were detected, with LOD scoring 3.81 and 2.86 on chromosome 4 and 8, and explained 16.8% and 9.9% of the phenotypic variance, respectively. Further analysis of epistatic effected QTLs for relative heat tolerance showed that four pairs of loci exhibited interaction on 8 chromosomes, which indicated that the heat tolerance of spikelet fertility was not only controlled by main effect QTL but also influenced by gene interaction.

Key words: Rice, Heat stress, Heat tolerance at the booting stage, QTLs