Abstract
In carrot somatic embryogenesis, 2,4-D promotes the transition from organized somatic cells to cells that have embryogenic function. However, 2,4-D has well known to inhibit development of embryogenic cell clusters to embryos. We examined in what manner the development of cell clusters to embryos was inhibited by 2,4-D in this study.
We observed with SEM that the membrane on superficial cells of cell clusters treated with 2,4-D was disrupted. The genes that were specifically expressed in cell clusters treated with 2,4-D were searched by subtraction method. Consequently we found a gene that had high homology with tomato polygalacturonase. Actually, we confirmed that high polygalacturonase activity was present in cell wall fraction of cell clusters treated with 2,4-D. We suppose that cell wall polygalacturonase induced with 2,4-D degrades pectin polysaccharides consisted of cell wall, resulting cessation of subsequent development of cell clusters by inhibition of cell elongation and adhesion between cells.
