Sun Tracking Science

Sunflowers efficiently track the apparent movement of the sun across the sky. Laboratory studies at the University of California Davis, using artificial light, suggested these flowers orientate themselves using a mechanism apparently common to other plants. Here, activating phototropins (blue light receptors) on the illuminated side of the plant's stem, concentrates auxins (plant hormones) on its unlit side. These auxins lengthen the cells, causing the stem to bend towards the light source. The Davis researchers went on to analyse the genes, switched within Sunflower stems, when illuminated on one side indoors with artificial blue light. Genes related to phototropins appeared activated on the stem's lit side. Conversely, genes related to auxin production and cell growth seemed to be 'switched on' on the shaded side. QED? This didn't, however, appear to happen in actual sunshine (https://www.theguardian.com/science/2023/oct/31/seeds-of-doubt-mystery-remains-over-how-sunflowers-track-light). In field studies, the Davis scientists found little difference in gene activities on the illuminated and non-illuminated sides of the Sunflower's stem. Findings obtained in controlled environments don't appear to be replicated by Sunflowers in the real world. Sun tracking by sunflowers retains its mystery.