Department of Botany, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom.
Plant Physiol. 1992 Nov;100(3):1177-83. doi: 10.1104/pp.100.3.1177.
Mechanically isolated asparagus (Asparagus officinalis) mesophyll cells dedifferentiate and divide when cultured in the dark in a medium containing sucrose. A strong correlation was observed between the onset of cell division and a loss of photosynthetic capacity. For the first 8 to 9 d of culture, there was no change in chloroplast size or morphology. However, following this period, the chloroplasts divided to form smaller proplastid-like structures. The gross chlorophyll content of the cell population did not change, suggesting that the loss of photosynthetic potential was not by senescence. Northern analysis showed that mRNA of the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase was undetectable within 1 d postisolation, which was quicker than in dark-treated plants. The mRNA of the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase decreased to low levels within 2 d of cell isolation. Both the large and small subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase protein showed a gradual reduction in abundance, falling to basal levels by days 6 to 7, which coincided with the onset of rapid cell division. A similar trend was observed with chloroplast rRNA molecules, which decreased to basal levels by day 6 in culture.
在黑暗条件下、含有蔗糖的培养基中培养时，被机械分离的芦笋（石刁柏）叶肉细胞会去分化并进行分裂。细胞分裂的开始与光合作用能力的丧失之间存在很强的相关性。在培养的前 8 到 9 天，叶绿体的大小或形态没有变化。然而，在此之后，叶绿体分裂形成更小的前质体样结构。细胞群体的总叶绿素含量没有变化，这表明光合作用潜力的丧失不是由衰老引起的。Northern 分析显示，在分离后 1 天内，1,5-二磷酸核酮糖羧化酶/加氧酶的大亚基 mRNA 无法检测到，这比在黑暗处理的植物中更快。1,5-二磷酸核酮糖羧化酶/加氧酶的大亚基 mRNA 在细胞分离后 2 天内降低到低水平。1,5-二磷酸核酮糖羧化酶/加氧酶的大亚基和小亚基蛋白的丰度也逐渐减少，到第 6 到 7 天降至基础水平，这与快速细胞分裂的开始相吻合。叶绿体 rRNA 分子也呈现出类似的趋势，在培养的第 6 天降至基础水平。
