A systems biology approach to dissect the contribution of brassinosteroid and auxin hormones to vascular patterning in the shoot of Arabidopsis thaliana.

Systems biology can foster our understanding of hormonal regulation of plant vasculature. One such example is our recent study on the role of plant hormones brassinosteroid (BR) and auxin in vascular patterning of Arabidopsis thaliana (Arabidopsis) shoots. By using a combined approach of mathematical modelling and molecular genetics, we have reported that auxin and BRs have complementary effects in the formation of the shoot vascular pattern. We proposed that auxin maxima, driven by auxin polar transport, position vascular bundles in the stem. BRs in turn modulate the number of vascular bundles, potentially by controlling cell division dynamics that enhance the number of provascular cells. Future interdisciplinary studies connecting vascular initiation at the shoot apex with the established vascular pattern in the basal part of the plant stem are now required to understand how and when the shoot vascular pattern emerges in the plant.