拟南芥根毛衰老死亡过程的PCD检测

Characterization of Programmed Cell Death During the Senescence of Root Hairs in Arabidopsis

根毛是植物体吸收养分的重要器官,自然条件下根毛的寿命很短,仅能存活2–3周,随即脱落死亡。以模式植物拟南芥(Arabidopsis thaliana)根毛为材料,对根毛死亡的细胞学特征进行了报道。结果发现,根毛衰老死亡后细胞内的原生质体发生了收缩,并在胞质中观察到凝集物的出现;通过原位末端标记(TUNEL)检测,发现幼根上的根毛细胞核DNA发生了片段化。上述结果表明,拟南芥根毛的衰老死亡很可能是植物体自主调控的程序性细胞死亡(PCD)。另外,当根毛衰老死亡后,细胞核大多会迁移到靠近根毛基部的位置,且正常的长管状根毛发生旋转扭曲。

The root hair is an essential organ for the uptake of nutrients in plants; root hair cells can only survive for 2 to 3 weeks and then die off, but the mechanisms underlying root hair death is not clear. In this study, we investigated the cellular characteristics of root hair death. Arabidopsis dying root hairs underwent protoplast retraction from the cell wall, and some unknown aggregates were observed in the cell. On detecting DNA fragmentation by terminal deoxynucleotide transferase-mediated d UTP nick-end labeling（TUNEL）, we found TUNEL-positive nuclei in root hairs. Protoplast retraction and nuclear DNA fragmentation are both considered hallmark features of apoptotic-like programmed cell death in plants. Therefore, we propose that the death of Arabidopsis root hairs belongs to programmed cell death, which is mediated by an intracellular program. As well, fluorescence staining with DAPI demonstrated that in dying root hairs, the nucleus would migrate to a position close to the basement of the root hair. Moreover, the tubular-shaped root hairs finally twist.