Molecular physiological aspects of chalking mechanism in rice grains under high-temperature stress

Toshiaki Mitsui, Hiromoto Yamakawa, Tohru Kobata

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


High-temperature stress during grain filling hastens the growth rate of endosperm and causes grain chalkiness. Scanning microscopy of chalky areas reveals loosely packed, rounded starch granules with occasional small pits. Intensive investigation of the transcriptome, proteome, and metabolome in developing caryopses under high-temperature stress revealed the downregulation of starch synthesis enzymes and the upregulation of α-amylases. High-temperature ripening may unbalance the synthesis and degradation of starch in the developing endosperm cells. In addition to starches, storage proteins are synthesized, assembled, and stored in developing seeds. Several lines of evidence suggest that redox regulation affects seed maturation, including the accumulation of storage starches and proteins, and thus grain quality. A heat-tolerant cultivar of rice shows a characteristic high expression of superoxide dismutase (SOD). H2 O2 produced by SOD under high-temperature stress possibly acts as a signal that rapidly can promote the expression of stress-response proteins. Herein, we will discuss the possible molecular physiology of grain chalking under high-temperature stress.

Original languageEnglish
Pages (from-to)22-29
Number of pages8
JournalPlant Production Science
Issue number1
Publication statusPublished - 2016


  • Chalky grain
  • Grain filling
  • Oryza sativa
  • Reactive oxygen species
  • Starch synthesis and degradation
  • Stress tolerance

ASJC Scopus subject areas

  • Agronomy and Crop Science


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