Abstract
Phototropism is caused by the accumulation of growth inhibitory substance(s) in the illuminated sides, interfering with the action of evenly distributed auxin. Based on this concept, benzoxazinoids (DIMBOA and MBOA) have been isolated as candidates for phototropism-regulating substances in maize coleoptiles. In our previous studies, it is suggested that blue light can induce the activity of β-glucosidase in the illuminated halves, resulting the up-regulation of DIMBOA level from its precursor DIMBOA glucoside. As a result, growth inhibition occurs in the illuminated sides that causes phototropic curvature. In this study, the transcriptional level of β-glucosidase and H2O2 level between the illuminated and shaded halves was investigated. Moreover, the level of benzoxazinoids with β-glucosidase inhibitor in both halves was also studied. The mechanism of growth inhibition in the illuminated sides in response to phototropic stimulation in maize coleoptiles will be discussed.
