Effect of phytohormones on seedling vigor of rice under cold conditions.

: We analyzed the relationship between seedling vigor and phytohormones at the seedling stage in foreign rice “Dunghan Shali” and “Italica Livorno” with vigorous initial growth under low temperature conditions, and Japanese rice “Oboroduki” and “Nipponbare”. The initial growth of “Dunghan Shali” and “Italica Livorno” was superior to that of “Oboroduki” and “Nipponbare” at both 27°C and 12°C. The phytohormone gibberellin supports vigorous initial growth of “Dunghan Shali”. The vigorous initial growth of “Italica Livorno” at 27°C could be induced by the effects of gibberellin since we noted increased expression of OsGA20ox1 , a gene that promotes gibberellin biosynthesis. Both “Dunghan Shali” and “Italica Livorno” harbor common mutations in the promoter region of OsGA20ox1 . At 12°C, the vigorous initial growth of “Italica Livorno” was because of the increased expression of OsGA20ox1 . In “Dunghan Shali”, although the expression of OsGA20ox1 was not high, the level of abscisic acid, which suppresses plant growth, was lower than that in the three other varieties. We conclude that the effect of gibberellin was important for the vigorous initial growth of rice seedlings at 27°C, but a balance of multiple phytohormones may be important for the seedling vigor in rice at 12°C.

[1]  E. Nambara,et al.  Sustained low abscisic acid levels increase seedling vigor under cold stress in rice (Oryza sativa L.) , 2015, Scientific Reports.

[2]  I. Mori,et al.  Ozone-Induced Rice Grain Yield Loss Is Triggered via a Change in Panicle Morphology That Is Controlled by ABERRANT PANICLE ORGANIZATION 1 Gene , 2015, PloS one.

[3]  Yutaka Sato,et al.  Salicylic acid antagonizes abscisic acid inhibition of shoot growth and cell cycle progression in rice , 2014, Scientific Reports.

[4]  Yutaka Sato,et al.  Generation of transgenic rice expressing heat shock protein genes under cool conditions , 2013 .

[5]  Chengcai Chu,et al.  The rice GERMINATION DEFECTIVE 1, encoding a B3 domain transcriptional repressor, regulates seed germination and seedling development by integrating GA and carbohydrate metabolism , 2013, The Plant journal : for cell and molecular biology.

[6]  R. Terauchi,et al.  OsGA20ox1, a candidate gene for a major QTL controlling seedling vigor in rice , 2012, Theoretical and Applied Genetics.

[7]  M. Matsuoka,et al.  Efficacy of microarray profiling data combined with QTL mapping for the identification of a QTL gene controlling the initial growth rate in rice. , 2012, Plant & cell physiology.

[8]  Jianhua Zhang,et al.  Ascorbic acid and reactive oxygen species are involved in the inhibition of seed germination by abscisic acid in rice seeds , 2011, Journal of experimental botany.

[9]  M. Yano,et al.  Molecular identification of a major quantitative trait locus, qLTG3–1, controlling low-temperature germinability in rice , 2008, Proceedings of the National Academy of Sciences.

[10]  Y. Kamiya,et al.  Ethylene promotes submergence-induced expression of OsABA8ox1, a gene that encodes ABA 8'-hydroxylase in rice. , 2006, Plant & cell physiology.

[11]  H. Yoshida,et al.  A role of OsGA20ox1, encoding an isoform of gibberellin 20-oxidase, for regulation of plant stature in rice , 2004, Plant Molecular Biology.

[12]  T. M. Squires,et al.  Induction of (+)-abscisic acid 8′ hydroxylase by (+)-abscisic acid in cultured maize cells , 1997 .

[13]  M. L. Peterson,et al.  Relations Between Alpha-amylase Activity at and Growth of Rice Seedlings 1 , 1973 .

[14]  笹原 健夫,et al.  Genetic variations in embryo and endosperm weights, seedling growth parameters and alpha-amylase activity of the germinated grains in rice (Oryza sativa L.). , 1986 .