Light-Dependent Chloroplast Movement in Wild Strawberry (Fragaria Vesca)
Abstract
Chloroplast photorelocation is a vital organellar response that optimizes photosynthesis in plants amid fluctuating environmental conditions. Chloroplasts exhibit an accumulation response, in which they move toward weak light to enhance photoreception, and an avoidance response, in which they move away from strong light to avoid photodamage. Although chloroplast photorelocation has been extensively studied in model plants such as Arabidopsis thaliana, little is known about this process in the economically important crop strawberry. This study, investigated chloroplast photorelocation in leaf mesophyll cells of wild strawberry (Fragaria vesca), a diploid relative of commercially cultivated octoploid strawberry (F. × ananassa). The study determined the induction of avoidance & accumulation response by blue and red light, and the cold dark response induction in F. vesca. Microscopy observation revealed that the periclinal area of leaf mesophyll cells in F. vesca is considerably smaller than that of A. thaliana. Given this small cell size, chloroplast photorelocation in F. vesca was investigated by first visualizing the responses using the white and green band assays and then by measuring light transmittance in leaves and obtaining the change in transmittance with respect to change in light intensities. Weak blue light-induced the accumulation response, whereas strong blue light induced the avoidance response. When light is switch off in the light transmittance set up, the amount of light passing through drops considerably indicating a dark positioning response. Also, inter-merit light that’s unable to induce any visible change in normal temperature shifts to induce an avoidance response in cold temperature. Unexpectedly, strong red light also induced the accumulation response in F. vesca. These findings shed light on chloroplast photorelocation as an intracellular response, laying the foundation for enhancing photosynthesis and productivity in Fragaria.