Kanako Ishiyama

Publications (12)107.32 Total impact

• Article: Mapping and characterization of seed dormancy QTLs using chromosome segment substitution lines in rice.

  Salem Marzougui, Kazuhiko Sugimoto, Utako Yamanouchi, Masaki Shimono, Tomoki Hoshino, Kiyosumi Hori, Masatomo Kobayashi, Kanako Ishiyama, Masahiro Yano
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  ABSTRACT: Seed dormancy--the temporary failure of a viable seed to germinate under favorable conditions--is a complex characteristic influenced by many genes and environmental factors. To detect the genetic factors associated with seed dormancy in rice, we conducted a QTL analysis using chromosome segment substitution lines (CSSLs) derived from a cross between Nona Bokra (strong dormancy) and Koshihikari (weak dormancy). Comparison of the levels of seed dormancy of the CSSLs and their recurrent parent Koshihikari revealed that two chromosomal regions-on the short arms of chromosomes 1 and 6-were involved in the variation in seed dormancy. Further genetic analyses using an F(2) population derived from crosses between the CSSLs and Koshihikari confirmed the allelic differences and the chromosomal locations of three putative QTLs: Sdr6 on chromosome 1 and Sdr9 and Sdr10 on chromosome 6. The Nona Bokra alleles of the three QTLs were associated with decreased germination rate. We discuss the physiological features of the CSSLs and speculate on the possible mechanisms of dormancy in light of the newly detected QTLs.
  Theoretical and Applied Genetics 11/2011; 124(5):893-902. · 3.30 Impact Factor
• Article: Molecular cloning of Sdr4, a regulator involved in seed dormancy and domestication of rice.

  Kazuhiko Sugimoto, Yoshinobu Takeuchi, Kaworu Ebana, Akio Miyao, Hirohiko Hirochika, Naho Hara, Kanako Ishiyama, Masatomo Kobayashi, Yoshinori Ban, Tsukaho Hattori, Masahiro Yano
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  ABSTRACT: Seed dormancy provides a strategy for flowering plants to survive adverse natural conditions. It is also an important agronomic trait affecting grain yield, quality, and processing performance. We cloned a rice quantitative trait locus, Sdr4, which contributes substantially to differences in seed dormancy between japonica (Nipponbare) and indica (Kasalath) cultivars. Sdr4 expression is positively regulated by OsVP1, a global regulator of seed maturation, and in turn positively regulates potential regulators of seed dormancy and represses the expression of postgerminative genes, suggesting that Sdr4 acts as an intermediate regulator of dormancy in the seed maturation program. Japonica cultivars have only the Nipponbare allele (Sdr4-n), which endows reduced dormancy, whereas both the Kasalath allele (Srd4-k) and Sdr4-n are widely distributed in the indica group, indicating prevalent introgression. Srd4-k also is found in the wild ancestor Oryza rufipogon, whereas Sdr4-n appears to have been produced through at least two mutation events from the closest O. rufipogon allele among the accessions examined. These results are discussed with respect to possible selection of the allele during the domestication process.
  Proceedings of the National Academy of Sciences 03/2010; 107(13):5792-7. · 9.68 Impact Factor
• Article: Three SnRK2 protein kinases are the main positive regulators of abscisic acid signaling in response to water stress in Arabidopsis.

  Yasunari Fujita, Kazuo Nakashima, Takuya Yoshida, Takeshi Katagiri, Satoshi Kidokoro, Norihito Kanamori, Taishi Umezawa, Miki Fujita, Kyonoshin Maruyama, Kanako Ishiyama, Masatomo Kobayashi, Shoko Nakasone, Kohji Yamada, Takuya Ito, Kazuo Shinozaki, Kazuko Yamaguchi-Shinozaki
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  ABSTRACT: Responses to water stress are thought to be mediated by transcriptional regulation of gene expression via reversible protein phosphorylation events. Previously, we reported that bZIP (basic-domain leucine zipper)-type AREB/ABF (ABA-responsive element-binding protein/factor) transcription factors are involved in ABA signaling under water stress conditions in Arabidopsis. The AREB1 protein is phosphorylated in vitro by ABA-activated SNF1-related protein kinase 2s (SnRK2s) such as SRK2D/SnRK2.2, SRK2E/SnRK2.6 and SRK2I/SnRK2.3 (SRK2D/E/I). Consistent with this, we now show that SRK2D/E/I and AREB1 co-localize and interact in nuclei in planta. Our results show that unlike srk2d, srk2e and srk2i single and double mutants, srk2d srk2e srk2i (srk2d/e/i) triple mutants exhibit greatly reduced tolerance to drought stress and highly enhanced insensitivity to ABA. Under water stress conditions, ABA- and water stress-dependent gene expression, including that of transcription factors, is globally and drastically impaired, and jasmonic acid (JA)-responsive and flowering genes are up-regulated in srk2d/e/i triple mutants, but not in other single and double mutants. The down-regulated genes in srk2d/e/i and areb/abf triple mutants largely overlap in ABA-dependent expression, supporting the view that SRK2D/E/I regulate AREB/ABFs in ABA signaling in response to water stress. Almost all dehydration-responsive LEA (late embryogenesis abundant) protein genes and group-A PP2C (protein phosphatase 2C) genes are strongly down-regulated in the srk2d/e/i triple mutants. Further, our data show that these group-A PP2Cs, such as HAI1 and ABI1, interact with SRK2D. Together, our results indicate that SRK2D/E/I function as main positive regulators, and suggest that ABA signaling is controlled by the dual modulation of SRK2D/E/I and group-A PP2Cs.
  Plant and Cell Physiology 10/2009; 50(12):2123-32. · 4.70 Impact Factor
• Article: Three Arabidopsis SnRK2 protein kinases, SRK2D/SnRK2.2, SRK2E/SnRK2.6/OST1 and SRK2I/SnRK2.3, involved in ABA signaling are essential for the control of seed development and dormancy.

  Kazuo Nakashima, Yasunari Fujita, Norihito Kanamori, Takeshi Katagiri, Taishi Umezawa, Satoshi Kidokoro, Kyonoshin Maruyama, Takuya Yoshida, Kanako Ishiyama, Masatomo Kobayashi, Kazuo Shinozaki, Kazuko Yamaguchi-Shinozaki
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  ABSTRACT: ABA is an important phytohormone regulating various plant processes, including stress tolerance, seed development and germination. SRK2D/SnRK2.2, SRK2E/SnRK2.6/OST1 and SRK2I/SnRK2.3 are redundant ABA-activated SNF1-related protein kinases 2 (SnRK2s) in Arabidopsis thaliana. We examined the role of these protein kinases in seed development and germination. These SnRK2 proteins were mainly expressed in the nucleus during seed development and germination. The triple mutant (srk2d srk2e srk2i) was sensitive to desiccation and showed severe growth defects during seed development. It exhibited a loss of dormancy and elevated seed ABA content relative to wild-type plants. The severity of these phenotypes was far stronger than that of any single or double SRK2D, SRK2E and SRK2I mutants, including the srk2d srk2i mutant. The triple mutant had greatly reduced phosphorylation activity in in-gel kinase experiments using basic leucine zipper (bZIP) transcription factors including ABI5. Microarray experiments revealed that 48 and 30% of the down-regulated genes in abi5 and abi3 seeds were suppressed in the triple mutant seeds, respectively. Moreover, disruption of the three protein kinases induced global changes in the up-regulation of ABA-repressive gene expression, as well as the down-regulation of ABA-inducible gene expression. These alterations in gene expression result in a loss of dormancy and severe growth defects during seed development. Collectively, these results indicate that SRK2D, SRK2E and SRK2I protein kinases involved in ABA signaling are essential for the control of seed development and dormancy through the extensive control of gene expression.
  Plant and Cell Physiology 07/2009; 50(7):1345-63. · 4.70 Impact Factor
• Source

  Available from: Shigeo Toh

  Article: High temperature-induced abscisic acid biosynthesis and its role in the inhibition of gibberellin action in Arabidopsis seeds.

  Shigeo Toh, Akane Imamura, Asuka Watanabe, Kazumi Nakabayashi, Masanori Okamoto, Yusuke Jikumaru, Atsushi Hanada, Yukie Aso, Kanako Ishiyama, Noriko Tamura, Satoshi Iuchi, Masatomo Kobayashi, Shinjiro Yamaguchi, Yuji Kamiya, Eiji Nambara, Naoto Kawakami
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  ABSTRACT: Suppression of seed germination at supraoptimal high temperature (thermoinhibiton) during summer is crucial for Arabidopsis (Arabidopsis thaliana) to establish vegetative and reproductive growth in appropriate seasons. Abscisic acid (ABA) and gibberellins (GAs) are well known to be involved in germination control, but it remains unknown how these hormone actions (metabolism and responsiveness) are altered at high temperature. Here, we show that ABA levels in imbibed seeds are elevated at high temperature and that this increase is correlated with up-regulation of the zeaxanthin epoxidase gene ABA1/ZEP and three 9-cis-epoxycarotenoid dioxygenase genes, NCED2, NCED5, and NCED9. Reverse-genetic studies show that NCED9 plays a major and NCED5 and NCED2 play relatively minor roles in high temperature-induced ABA synthesis and germination inhibition. We also show that bioactive GAs stay at low levels at high temperature, presumably through suppression of GA 20-oxidase genes, GA20ox1, GA20ox2, and GA20ox3, and GA 3-oxidase genes, GA3ox1 and GA3ox2. Thermoinhibition-tolerant germination of loss-of-function mutants of GA negative regulators, SPINDLY (SPY) and RGL2, suggests that repression of GA signaling is required for thermoinibition. Interestingly, ABA-deficient aba2-2 mutant seeds show significant expression of GA synthesis genes and repression of SPY expression even at high temperature. In addition, the thermoinhibition-resistant germination phenotype of aba2-1 seeds is suppressed by a GA biosynthesis inhibitor, paclobutrazol. We conclude that high temperature stimulates ABA synthesis and represses GA synthesis and signaling through the action of ABA in Arabidopsis seeds.
  Plant physiology 04/2008; 146(3):1368-85. · 6.53 Impact Factor
• Article: Dissection of the phosphorylation of rice DELLA protein, SLENDER RICE1.

  Hironori Itoh, Akie Sasaki, Miyako Ueguchi-Tanaka, Kanako Ishiyama, Masatomo Kobayashi, Yasuko Hasegawa, Eiichi Minami, Motoyuki Ashikari, Makoto Matsuoka
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  ABSTRACT: DELLA proteins are repressors of gibberellin signaling in plants. Our previous studies have indicated that gibberellin signaling is derepressed by SCF(GID2)-mediated proteolysis of the DELLA protein, SLENDER RICE1 (SLR1), in rice. In addition, the gibberellin-dependent increase of phosphorylated SLR1 in the loss-of-function gid2 mutant suggests that the SCF(GID2)-mediated degradation of SLR1 might be initiated by gibberellin-dependent phosphorylation. To confirm the role of phosphorylation of SLR1 in its gibberellin-dependent degradation, we revealed that SLR1 is phosphorylated on an N-terminal serine residue(s) within the DELLA/TVHYNP and polyS/T/V domain. However, gibberellin-induced phosphorylation in these regions was not observed in the gid2 mutant following the constitutive expression of SLR1 under the control of the rice actin1 promoter. Treatment with gibberellin induced both the phosphorylated and non-phosphorylated forms of SLR1 with similar induction kinetics in gid2 mutant cells. Both the phosphorylated and non-phosphorylated SLR1 proteins were degraded by gibberellin treatment with a similar half-life in the rice callus cells, and both proteins interacted with recombinant glutathione S-transferase (GST)-GID2. These results demonstrate that the phosphorylation of SLR1 is independent of its degradation and is dispensable for the interaction of SLR1 with the GID2/F-box protein.
  Plant and Cell Physiology 09/2005; 46(8):1392-9. · 4.70 Impact Factor
• Article: An important role of phosphatidic acid in ABA signaling during germination in Arabidopsis thaliana.

  Takeshi Katagiri, Kanako Ishiyama, Tomohiko Kato, Satoshi Tabata, Masatomo Kobayashi, Kazuo Shinozaki
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  ABSTRACT: Phosphatidic acid (PA) functions as a lipid signaling molecule in plants. Physiological analysis showed that PA triggers early signal transduction events that lead to responses to abscisic acid (ABA) during seed germination. We measured PA production during seed germination and found increased PA levels during early germination. To investigate the role of PA during seed germination, we focused on the PA catabolic enzyme lipid phosphate phosphatase (LPP). LPP catalyzes the conversion of PA to diacylglycerol (DAG). There are 4 LPP genes in the Arabidopsis genome. Among them, AtLPP2 and AtLPP3 are expressed during seed germination. Two AtLPP2 T-DNA insertional mutants (lpp2-1 and lpp2-2) showed hypersensitivity to ABA and significant PA accumulation during germination. Furthermore, double-mutant analysis showed that ABA-insensitive 4 (ABI4) is epistatic to AtLPP2 but ABA-insensitive 3 (ABI3) is not. These results suggest that PA is involved in ABA signaling and that AtLPP2 functions as a negative regulator upstream of ABI4, which encodes an AP2-type transcription factor, in ABA signaling during germination.
  The Plant Journal 08/2005; 43(1):107-17. · 6.16 Impact Factor
• Article: Comparative genomics in salt tolerance between Arabidopsis and aRabidopsis-related halophyte salt cress using Arabidopsis microarray.

  Teruaki Taji, Motoaki Seki, Masakazu Satou, Tetsuya Sakurai, Masatomo Kobayashi, Kanako Ishiyama, Yoshihiro Narusaka, Mari Narusaka, Jian-Kang Zhu, Kazuo Shinozaki
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  ABSTRACT: Salt cress (Thellungiella halophila), a halophyte, is a genetic model system with a small plant size, short life cycle, copious seed production, small genome size, and an efficient transformation. Its genes have a high sequence identity (90%-95% at cDNA level) to genes of its close relative, Arabidopsis. These qualities are advantageous not only in genetics but also in genomics, such as gene expression profiling using Arabidopsis cDNA microarrays. Although salt cress plants are salt tolerant and can grow in 500 mm NaCl medium, they do not have salt glands or other morphological alterations either before or after salt adaptation. This suggests that the salt tolerance in salt cress results from mechanisms that are similar to those operating in glycophytes. To elucidate the differences in the regulation of salt tolerance between salt cress and Arabidopsis, we analyzed the gene expression profiles in salt cress by using a full-length Arabidopsis cDNA microarray. In salt cress, only a few genes were induced by 250 mm NaCl stress in contrast to Arabidopsis. Notably a large number of known abiotic- and biotic-stress inducible genes, including Fe-SOD, P5CS, PDF1.2, AtNCED, P-protein, beta-glucosidase, and SOS1, were expressed in salt cress at high levels even in the absence of stress. Under normal growing conditions, salt cress accumulated Pro at much higher levels than did Arabidopsis, and this corresponded to a higher expression of AtP5CS in salt cress, a key enzyme of Pro biosynthesis. Furthermore, salt cress was more tolerant to oxidative stress than Arabidopsis. Stress tolerance of salt cress may be due to constitutive overexpression of many genes that function in stress tolerance and that are stress inducible in Arabidopsis.
  Plant physiology 08/2004; 135(3):1697-709. · 6.53 Impact Factor
• Article: An overview of gibberellin metabolism enzyme genes and their related mutants in rice.

  Tomoaki Sakamoto, Koutarou Miura, Hironori Itoh, Tomoko Tatsumi, Miyako Ueguchi-Tanaka, Kanako Ishiyama, Masatomo Kobayashi, Ganesh K Agrawal, Shin Takeda, Kiyomi Abe, Akio Miyao, Hirohiko Hirochika, Hidemi Kitano, Motoyuki Ashikari, Makoto Matsuoka
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  ABSTRACT: To enhance our understanding of GA metabolism in rice (Oryza sativa), we intensively screened and identified 29 candidate genes encoding the following GA metabolic enzymes using all available rice DNA databases: ent-copalyl diphosphate synthase (CPS), ent-kaurene synthase (KS), ent-kaurene oxidase (KO), ent-kaurenoic acid oxidase (KAO), GA 20-oxidase (GA20ox), GA 3-oxidase (GA3ox), and GA 2-oxidase (GA2ox). In contrast to the Arabidopsis genome, multiple CPS-like, KS-like, and KO-like genes were identified in the rice genome, most of which are contiguously arranged. We also identified 18 GA-deficient rice mutants at six different loci from rice mutant collections. Based on the mutant and expression analyses, we demonstrated that the enzymes catalyzing the early steps in the GA biosynthetic pathway (i.e. CPS, KS, KO, and KAO) are mainly encoded by single genes, while those for later steps (i.e. GA20ox, GA3ox, and GA2ox) are encoded by gene families. The remaining CPS-like, KS-like, and KO-like genes were likely to be involved in the biosynthesis of diterpene phytoalexins rather than GAs because the expression of two CPS-like and three KS-like genes (OsCPS2, OsCPS4, OsKS4, OsKS7, and OsKS8) were increased by UV irradiation, and four of these genes (OsCPS2, OsCPS4, OsKS4, and OsKS7) were also induced by an elicitor treatment.
  Plant physiology 05/2004; 134(4):1642-53. · 6.53 Impact Factor
• Article: Genetic manipulation of gibberellin metabolism in transgenic rice.

  Tomoaki Sakamoto, Yoichi Morinaka, Kanako Ishiyama, Masatomo Kobayashi, Hironori Itoh, Toshiaki Kayano, Shuichi Iwahori, Makoto Matsuoka, Hiroshi Tanaka
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  ABSTRACT: The 'green revolution' was fueled by the introduction of the semi-dwarf trait into cereal crop cultivars. The semi-dwarf cultivars--which respond abnormally to the plant growth hormone gibberellin (GA)--are more resistant to wind and rain damage and thus yield more grain when fertilized. To generate dwarf rice plants using a biotechnological approach, we modified the level of GA by overproduction of a GA catabolic enzyme, GA 2-oxidase. When the gene encoding GA 2-oxidase, OsGA2ox1, was constitutively expressed by the actin promoter, transgenic rice showed severe dwarfism but failed to set grain because GA is involved in both shoot elongation and reproductive development. In contrast, OsGA2ox1 ectopic expression at the site of bioactive GA synthesis in shoots under the control of the promoter of a GA biosynthesis gene, OsGA3ox2 (D18), resulted in a semi-dwarf phenotype that is normal in flowering and grain development. The stability and inheritance of these traits shows the feasibility of genetic improvement of cereal crops by modulation of GA catabolism and bioactive GA content.
  Nature Biotechnology 09/2003; 21(8):909-13. · 23.27 Impact Factor
• Source

  Available from: postech.ac.kr

  Article: Accumulation of phosphorylated repressor for gibberellin signaling in an F-box mutant.

  Akie Sasaki, Hironori Itoh, Kenji Gomi, Miyako Ueguchi-Tanaka, Kanako Ishiyama, Masatomo Kobayashi, Dong-Hoon Jeong, Gynheung An, Hidemi Kitano, Motoyuki Ashikari, Makoto Matsuoka
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  ABSTRACT: Gibberellin (GA) regulates growth and development in plants. We isolated and characterized a rice GA-insensitive dwarf mutant, gid2. The GID2 gene encodes a putative F-box protein, which interacted with the rice Skp1 homolog in a yeast two-hybrid assay. In gid2, a repressor for GA signaling, SLR1, was highly accumulated in a phosphorylated form and GA increased its concentration, whereas SLR1 was rapidly degraded by GA through ubiquitination in the wild type. We conclude that GID2 is a positive regulator of GA signaling and that regulated degradation of SLR1 is initiated through GA-dependent phosphorylation and finalized by an SCF(GID2)-proteasome pathway.
  Science 04/2003; 299(5614):1896-8. · 31.20 Impact Factor
• Article: High Temperature-Induced Abscisic Acid Biosynthesis and Its Role in the Inhibition of Gibberellin Action in

  Shigeo Toh, Akane Imamura, Asuka Watanabe, Kazumi Nakabayashi, Masanori Okamoto, Yusuke Jikumaru, Atsushi Hanada, Yukie Aso, Kanako Ishiyama, Noriko Tamura, Masatomo Kobayashi, Shinjiro Yamaguchi