Prediction of prospective leaf morphology in lettuce based on intracellular chloroplast position

In the accumulation response, chloroplasts move toward weak blue light, staying at positions along the periclinal cell wall. By contrast, in the avoidance response, chloroplasts move away from strong blue light, escaping to positions along the anticlinal cell wall. The accumulation response maximizes light capture and the avoidance response reduces photodamage. The intracellular positioning of chloroplasts is important for optimizing photosynthesis and may have common signals with the regulators that determine leaf morphology, another factor that affects photosynthesis. Here, we propose that intracellular chloroplast position can be used to predict prospective leaf morphology in lettuce (Lactuca sativa). To test this, we induced the accumulation or avoidance response in lettuce cells through exposure to the appropriate strength of blue light and observed the growth of the plants. Our results indicated that leaf area increased in response to weak blue light inducing the accumulation response, and leaf thickness increased in response to strong blue light inducing the avoidance response.