Required for normal plant growth. May be both photoprotective and play an ancillary role in photosynthesis. May structurally stabilize thylakoids during osmotic and oxidative stress. Associates with the major light-harvesting antenna complex polypeptides of the PSII oxygen-evolving complex. Expressed at high levels in leaves and in the petals and anthers of flowers. Up-regulated in the leaves during tuberization. By light. Levels increase upon illumination and stay high in daylight, dropping back to basal levels in darkness. Belongs to the LIPC family.