Fath A, Bethke P C, Jones R L
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102, USA.
Plant J. 1999 Nov;20(3):305-15.
Barley aleurone cells undergo programmed cell death (PCD) when exposed to gibberellic acid (GA), but incubation in abscisic acid (ABA) prevent PCD. We tested the hypothesis that PCD in aleurone cells occurs by apoptosis, and show that the hallmark of apoptosis, namely DNA cleavage into 180 bp fragments, plasma membrane blebbing, and the formation of apoptotic bodies do not occur when aleurone cells die. We show that endogenous barley aleurone nucleases and nucleases present in enzymes used for protoplast preparation degrade aleurone DNA and that DNA degradation by these nucleases is rapid and can result in the formation of 180 bp DNA ladders. Methods are described that prevent DNA degradation during isolation from aleurone layers or protoplasts. Barley aleurone cells contain three nucleases whose activities are regulated by GA and ABA. CA induction and ABA repression of nuclease activities correlate with PCD in aleurone cells. Cells incubated in ABA remain alive and do not degrade their DNA, but living aleurone cells treated with GA accumulate nucleases and hydrolyze their nuclear DNA. We propose that barley nucleases play a role in DNA cleavage during aleurone PCD.
大麦糊粉层细胞在接触赤霉素（GA）时会经历程序性细胞死亡（PCD），但在脱落酸（ABA）中孵育可防止PCD。我们检验了糊粉层细胞中的PCD通过凋亡发生的假说，并表明当糊粉层细胞死亡时，凋亡的标志，即DNA裂解为180 bp片段、质膜起泡和凋亡小体的形成并未发生。我们表明，大麦糊粉层细胞内源性核酸酶以及用于原生质体制备的酶中存在的核酸酶会降解糊粉层DNA，并且这些核酸酶对DNA的降解速度很快，可导致形成180 bp的DNA梯状条带。文中描述了在从糊粉层或原生质体分离过程中防止DNA降解的方法。大麦糊粉层细胞含有三种核酸酶，其活性受GA和ABA调节。核酸酶活性的CA诱导和ABA抑制与糊粉层细胞中的PCD相关。在ABA中孵育的细胞保持存活且不会降解其DNA，但用GA处理的活糊粉层细胞会积累核酸酶并水解其核DNA。我们提出大麦核酸酶在糊粉层PCD期间的DNA裂解中起作用。
