| 研究実績の概要 |
Rice plants deficient in JA-Ile formation are sterile. To determine contribution of various jasmonates and other hormones in flower development in rice, in 2016 we investigated jasmonates (JA, JA-Ile, OH-JA, OH-JA-Ile, COOH-JA-Ile), salicylate and abscisic acid at four stages of flowers (pre-anthesis, anthesis, post-anthesis, and seed formation stage). Maximum accumulation of JA and JA-Ile was confirmed during anthesis in rice flowers. While abscisic acid did not show changes during flower development, salicylic acid has accumulated mainly after anthesis and during seed development. In JAR1 mutant flowers, JA-Ile contents were downregulated and JA increased (compensatory response). Next we investigated the expression of key MADS box (flower identity) genes in rice flowers of wild type and JAR1 mutant by qPCR using cDNA material available in the laboratory. Expression of most MADS box genes was highest before and during anthesis, however there were no major changes found between wild type and JAR1 mutant. It suggests that MADS box gene expression if independent of jasmonate signaling. Secondly, it suggests that factor(s) other than MADS genes is causative reasons for complete failure of seed development in JAR1 rice. Finally, we verified the flower deficient phenotype in hebiba mutant lacking jasmonate synthesis.
In addition to original plan, we also examined the experimental potential of Sorghum bicolor as another useful monocot plant model to be used in the study. In the first stage, content and potential roles of jasmonates sorghum plants were investigated.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
Main reason is that grant decision received on 10/21/2016 (additional announcements). Despite this, we accomplished several important experiments such as basic characterization of rice plant materials, JAR1 and hebiba mutants in six months of FY2016. However, field experiment and sampling for microarray experiment could not be conducted due to delayed approval (field season was in May-August). According to newly modified plan, field sampling and microarray analyses will be conducted in summer of FY2017. To accelerate progress, funds and efforts will be used aggressively to compensate for delayed start and transition to second stage of this project that involves construction of transgenic plants silenced in genes putatively involved in jasmonate action in rice flower and seed development.
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| 今後の研究の推進方策 |
We focus on obtaining transriptome profiles from rice flowers. Data will be analyzed and differentially expressed genes will be identified. Subsequently, we will initiate cloning and construction of vectors necessary for silencing of jasmonate regulated flower specific genes. At first, five candidate genes will be selected and used. To obtain detailed information about distribution of hormones in flowers during anthesis, tissue specific samples will be collected from wild type Nipponbare rice and subjected to highly sensitive LC-MS/MS analysis. Next, the expression of jasmonate-regulated genes in flowers will be examined at tissue specific level to create support platform for functional characterization of these genes and their role in flowers.
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