3-Phenyllactic acid is converted to phenylacetic acid and induces auxin-responsive root growth in Arabidopsis plants

Many microorganisms have been reported to produce compounds that promote plant growth and are thought to be involved in the establishment and maintenance of symbiotic relationships. 3-Phenyllactic acid (PLA) produced by lactic acid bacteria was previously shown to promote root growth in adzuki cuttings. However, the mode of action of PLA as a root-promoting substance had not been clarified. The present study therefore investigated the relationship between PLA and auxin. PLA was found to inhibit primary root elongation and to increase lateral root density in wild-type Arabidopsis, but not in an auxin signaling mutant. In addition, PLA induced IAA19 promoter fused β-glucuronidase gene expression, suggesting that PLA exhibits auxin-like activity. The inability of PLA to promote degradation of Auxin/Indole-3-Acetic Acid protein in a yeast heterologous reconstitution system indicated that PLA may not a ligand of auxin receptor. Using of a synthetic PLA labeled with stable isotope showed that exogenously applied PLA was converted to phenylacetic acid (PAA), an endogenous auxin, in both adzuki and Arabidopsis. Taken together, these results suggest that exogenous PLA promotes auxin signaling by conversion to PAA, thereby regulating root growth in plants.     

Bluejay 1.0: genome browsing and comparison with rich customization provision and dynamic resource linking

Background  

The Bluejay genome browser has been developed over several years to address the challenges posed by the ever increasing number of data types as well as the increasing volume of data in genome research. Beginning with a browser capable of rendering views of XML-based genomic information and providing scalable vector graphics output, we have now completed version 1.0 of the system with many additional features. Our development efforts were guided by our observation that biologists who use both gene expression profiling and comparative genomics gain functional insights above and beyond those provided by traditional per-gene analyses.     

Syntheses of recombinant yellowtail and flounder growth hormones in Escherichia coli.

For syntheses of recombinant yellowtail and flounder growth hormones (r-yGH and r-fGH) in E. coli, expression plasmids were constructed. The expression level of r-yGH and r-fGH in the host cells were very high, reaching 15 and 8% of the total protein, respectively. These product proteins were accumulated in inclusion bodies in the cells. The recombinant hormones were isolated from the pellets ina glutathione reduction/oxidation buffer. The refolded hormones were further purified by DEAE-Toyopearl 650M chromatography to homogeneity. The purified r-yGH and r-fGH were composed of 188 and 174 amino acid residues, respectively, having amino-terminal sequences starting with methionine. The recombinant hormones had potent growth-promoting activities on juvenile rainbow trout Salmo gairdneri in a dose-dependent manner.     

3-Phenyllactic acid,a root-promoting substance isolated from Bokashi fertilizer,exhibits synergistic effects with tryptophan

Bokashi fertilizer, an organic fertilizer made of plant residue, has been used in Japan not only to fertilize plants but to regulate their growth. Lactic acid bacteria have been found to play an important role in the fermentation process of Bokashi, but the relationship between these bacteria and plant growth activity has not been clarified. Using the adzuki rooting assay, this study identified 3-phenyllactic acid (PLA) produced by lactic acid bacteria as a root promoting compound in Bokashi. PLA showed synergistic effect with tryptophan, but no stem elongation activity. Lactic acid bacteria produced equal quantities of the L- and D-forms of PLA, which have similar root promoting activity. PLA did not significantly affect the amount of endogenous indole-3-acetic acid (IAA), although the chemical structure of PLA is highly similar to that of L-2-aminooxy-3-phenypropionic acid (L-AOPP), which inhibits IAA biosynthesis. These results indicate that the root promoting activity of PLA is not simply due to its increase in the amount of active auxin.