撤除外源生长素诱发棉花胚性悬浮细胞程序性死亡

棉花胚性悬浮细胞在仅含生长素的MS培养基上培养时,生长良好;但当转入到不含生长素的MS培养基上培养时,大规模死亡.通过细胞学观察发现,在转入无生长素的MS培养基培养3～4 d后可见明显的核质浓缩、胞质收缩,而高温处理引起的细胞坏死无此现象.用抽提悬浮细胞基因组DNA进行凝胶电泳发现:这种细胞死亡还伴随有典型的DNA梯度出现,而坏死的细胞和对照无DNA梯度.表明这种由生长素撤除引起的细胞死亡是一种程序性死亡.这种细胞死亡能被水解酶抑制剂和半胱氨酸蛋白酶抑制剂抑制,表明水解酶和类半胱氨酸蛋白水解酶(CLP)参与细胞程序性死亡.

Withdrawal of Exogenous Auxin Induces Programmed Cell Death of Cotton Embryogenic Suspension Cultures

In the establishment of cotton suspension culture, we had observed an interesting phenomenon that large-scale cell death occurred when the embryogenic cells were transferred from the medium MS supplemented with IBA 0.5 mg/L to fresh MS medium without IBA. Cytological study and genomic DNA electro-phoresis showed that this kind of cell death was accompanied by such morphological characters as chromatin condensation, the maintenance of membrane continuity, a condensed cytoplasm and evident DNA fragmentation of multimers of 140-180 bp (Fig.3, Fig.4). Inhibitor studies suggested the proteolysis and the caspase-like proteases were involved in cell death (Fig.5, Fig.6). These results support that cell death caused by withdrawal of exogenous auxins is a kind of programmed cell death (PCD). So auxin is involved in the regulation of programmed cell death signal transduction pathways, and may be another plant-specific regulator beside ethylene, absci-sic acid and gibberellin in PCD.