Complex sentence: Kay then developed glowing "Arabidopsis thaliana" plants to screen for circadian rhythm mutants, with the help of his student Andrew Millar, and subsequently identified TOC1, the first clock gene identified in plants.
Split into simpler sentences: Kay then developed glowing "Arabidopsis thaliana" plants to screen for circadian rhythm mutants. With the help of his student Andrew Millar, Kay identified TOC1, the first clock gene identified in plants.