Abstract
High temperature impairs grain filling by inhibiting the deposition of storage materials such as starch. To comprehend its impact on grain filling metabolism in rice, levels of metabolites and transcripts related to central pathways of metabolism were simultaneously determined in developing caryopses exposed to high and control temperatures during the milky stage. A capillary electrophoresis-based metabolomic analysis revealed that high temperature increased the accumulation of sucrose and amino acids and decreased levels of sugar phosphates and organic acids. A transcriptomic analysis using a whole genome-covering microarray unraveled the possible metabolic steps causing the shortage of storage materials under the elevated temperature. Starch deposition might be impaired by down-regulation of sucrose import/degradation and starch biosynthesis, and/or up-regulation of starch degradation as well as inefficient ATP production by an inhibited cytochrome respiration chain, as indicated by the response of gene expression to high temperature. An atlas showing the effect of high temperature on levels of metabolites and gene expression in the central metabolic pathways is presented.
