Root growth profiles of Aveneae and Poeae plants in optically active α-methylbenzyl-3-p-tolylurea media

Using a root growth inhibition assay, we studied the diverse chiral responses of plants in the tribes, Aveneae and Poeae, to the optically active compounds, R- and S- 1-α-methylbenzyl-3- p -tolylurea (MBTU). We specifically examined the responses of grasses belonging to the Poeae tribe ( Lolium , Briza , Poa , Dactylis , and Festuca ) and the Aveneae tribe ( Avena , Holcus , Agrostis , Alopecurus , Beckmannia , and Phleum ). These plants include companion weeds of wheat and barley, and turf grass. The companion weeds of cereal crops, such as Poa annua , Poa pratensis , Dactylis glomerata , Avena fatua , Avena sativa , Holcus lanatus , Agrostis stolonifera , Alopecurus myosuroides , Al. aequalis , and Beckmannia syzigachne , showed significantly inhibited root growth in response to 20 µmol L⁻¹ R- MBTU, whereas the root growth of Triticum aestivum was not inhibited at this concentration. Like Oryza sativa , almost all the Poeae and Aveneae plants tested here preferentially responded to R -MBTU, but the four grasses, Lolium multiflorum , D. glomerata , Alopecurus species, and Phleum pratense , preferentially responded to S -MBTU. Among them, the Agrostis species were highly sensitive to R -MBTU and the Alopecurus species were highly sensitive to S -MBTU. All the plants among the genera, Poa , Avena , and Alopecurus , showed a homogeneous chiral preference.