干旱区生态环境知识资源中心

Primary roots of two species of Sonoran Desert Cactaceac, Stenecereus gummosus and Pachyccreus pringlei. have a determinate pattern of growth: meristematic cells divide only for a limited time and then differentiate. Detecting DNA fragmentation by terminal deoxynucleotide transferase-mediated dU/TP nick-end labeling (TUNEL), we have shown that programmed cell death (PCD) was not involved in meristem exhaustion. However, we found TUNEL-positive nuclei in the root hair and root cap cells of both species. Programmed cell death in root hair cells has not been previously reported and the pattern of PCD events in the root cap differed front that described earlier. These data suggest that in the studied Cactaceae, PCD is involved in developmental adaptations related to the formation of a compact root system important for rapid seedling establishment in a desert environment. Participation of PCD in developmental loss of the root Cap and in root hair renovation proposed in the current study implicates an evolutionary conserved link between PCD and differentiation processes in plants.