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High Temperature‐Induced Repression of the Rice Sucrose Transporter ( Os SUT 1 ) and Starch Synthesis‐Related Genes in Sink and Source Organs at Milky Ripening Stage Causes Chalky Grains
Author(s) -
Phan T. T. T.,
Ishibashi Y.,
Miyazaki M.,
Tran H. T.,
Okamura K.,
Tanaka S.,
Nakamura J.,
Yuasa T.,
IwayaInoue M.
Publication year - 2013
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/jac.12006
Subject(s) - starch , starch synthase , ripening , sucrose synthase , dry matter , biology , panicle , horticulture , grain quality , agronomy , chemistry , zoology , botany , sucrose , biochemistry , amylose , invertase , amylopectin
High temperatures during rice grain ripening reduced yield and grain quality. The proportion of milky white grains was 43.6 % at 30 °C but only 6.5 % at 25 °C. Grain filling was initially faster at 30 °C and finished earlier, and the final dry matter content was less, than at 25 °C. High temperature strongly suppressed the expression of the sucrose transporter gene O s SUT 1 and starch synthesis‐related genes S u S y2 , AGPS 2b , BEII b and Granule‐bound starch synthase in grains during early grain filling; the transcription levels of O s SUT 1 at 14 days after flowering ( DAF ) were about 60 % lower in grains, flag leaf blade, flag leaf sheath and first leaf sheath. These facts are possibly involved in the earlier termination of grain filling at 21 DAF , following the rapid rise of grain dry weight from 0 to 7 DAF , due to possible reduction in assimilate supply via O s SUT 1 under the high temperature. When panicles were partly clipped, the resultant increase in assimilate supply to the remaining grains significantly upregulated the expression of O s SUT 1 and the starch synthesis‐related genes at 14 DAF , which consequently accelerated starch accumulation in the grains and ultimately increased the grain weight of remaining grains at 30 °C. These results indicate that high temperature during grain filling reduces grain yield and quality by changing the expression of O s SUT 1 and starch synthase‐related genes, resulting in earlier ripening due to hastened or premature assimilate supply to grains.