NBRP, National Bioresource Project of Japan and plant bioresource management

The National BioResource Project has been organized and established to promote research activities using valuable bioresources. A total of twenty-eight bioresources for ten animals, nine plants and nine microorganisms/cell lines developed or collected in Japan were selected for the project. Resources are categorized into several different groups in the project; genetic resources, germplasm, genome resources and their information. Choices of how many resources must be preserved and maintained and in which categories are dependent on the status of the research community of each organism. These resources, if utilized systematically and intelligently, are powerful means for leading new scientific discoveries. Some examples can be seen in this paper. This paper reviews plant bioresources with the main focus on rice resource activities within the project

Molecular mechanism of crown root initiation and the different mechanisms between crown root and radicle in rice

Monocot plants produce numerous adventitious (crown) roots. The plant hormone auxin has positive effects on crown root formation, while cytokinin suppresses it. We have demonstrated that auxin-induced CROWN ROOTLESS5 (CRL5) regulates crown root initiation in rice through the induction of OsRR1, a negative regulator of cytokinin signaling. CRL5 overexpressing calli formed adventitious roots, although CRL5 overexpressing plants did not induce ectopic roots, suggesting that CRL5, which promotes de novo root initiation, might function only in de-differentiated cells. A radicle initiated normally in a crl5 mutant, in spite of the defect in crown root initiation, whereas crown roots, but not a radicle, were produced in a radicleless1 (ral1) mutant. A crl5 ral1 double mutant displayed an additive phenotype, showing that the formation of each root is regulated by different genetic mechanisms in rice

Rice ERECT LEAF 1 acts in an alternative brassinosteroid signaling pathway independent of the receptor kinase OsBRI1

<p>ERECT LEAF 1 (ELF1) was previously identified as a component of brassinosteroid signaling in rice. A double mutant obtained by crossing <i>elf1-1</i> (a null mutant of <i>ELF1</i>) with <i>d61-1</i> (a leaky mutant of <i>OsBRI1</i>) showed a more severe phenotype than did the <i>elf1-1</i> single mutant, resembling that of a severe brassinosteroid-deficient mutant. Microarray analysis showed that the gene expression profile of <i>elf1-1</i> was distinct from that of <i>d61-12</i> (a leaky mutant of <i>OsBRI1</i> with a phenotype similar to that of <i>elf1-1</i>), and fewer than half of genes differentially expressed between the wild-type and <i>elf1-1</i> showed similar differences in <i>d61-12</i> relative to the wild-type. These results indicate that less than half of ELF1-regulated genes in rice seedlings are affected by OsBRI1, and suggest that ELF1 acts in a rice brassinosteroid signaling pathway different from that initiated by OsBRI1. Gene expression analysis showed that some stress response-related genes were induced in <i>elf1-1</i> but not in <i>d61-12</i>, and 8 of 9 genes oppositely regulated in <i>elf1-1</i> and <i>d61-12</i> were significantly up- or down-regulated in both <i>elf1-1</i> and jasmonic acid-treated wild-type. These results imply that ELF1 suppresses stress-induced signalling, and that jasmonic acid signaling is stimulated in <i>elf1-1</i>; therefore, ELF1 may be involved in the brassinosteroid-mediated suppression of jasmonic acid response in rice.</p

Mechanical Stimulus-Sensitive Mutation, rrl3Affects the Cell Production Process in the Root Meristematic Zone in Rice

Genetic studies on the response of plant root to environmental stimuli are important for elucidating the mechanism of the stress tolerance of plants. We isolated and characterized a recessive rice mutant, rrl3,which was highly sensitive to mechanical stimulus and has short roots. No significant difference was observed between the seminal roots of rrl3mutant and wild type in the mean axial and radial length of mature cortical cells. On the other hand, meristematic zone of the root was smaller and the cortical cell flux in the growing zone of the root was significantly lower in the mutant than in the wild type. In addition, the rrl3mutant and the wild type did not differ in sensitivity to ethylene, IAA or ABA. These results suggest that the RRL3gene specifically regulates the cell production process in the root meristematic zone under a mechanically impeded condition and does not regulate the sensitivities to ethylene, IAA and ABA