The totipotency and relationship of seta-bearing cells to thallus development in the Green Alga Coleochaete Scutata. A laser microbeam study.

The relationship of seta-bearing cells of Coleochaete scutata (Chlorophyta Ulotrichales) to normal growth and development of the thallus was investigated using laser microbeam irradiation. When all of the seta-bearing cells of a thallus, except the small primary seta-bearing cell, were destroyed by laser microbeam irradiation, the thallus grew as rapidly as thalli that had received no radiation. The functional significance of the seta-bearing cell is still not understood, but it has been found that these cells have the capacity to dedifferentiate and divide to form normal vegetative and seta-bearing cells. Mechanisms controlling the number ofseta-bearing cells and growth of the thallus are discussed.