Light-dependent death of maize lls1 cells is mediated by mature chloroplasts
Light-dependent death of maize lls1 cells is mediated by mature chloroplasts
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DOI：
10.1104/pp.008441
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发表时间：
2002-12-01
期刊：
影响因子：
7.4
通讯作者：
Johal, GS
中科院分区：
文献类型：
--
作者：
Gray, J;Janick-Buckner, D;Johal, GS
我们先前报道了一个新的细胞死亡抑制基因从玉米（玉米）编码的Lls 1（致死叶斑-1）基因的分离。虽然LLS 1的确切代谢功能仍然难以捉摸，在这里，我们提供了深入了解与LLS 1病变相关的细胞死亡的启动和传播的机制。我们的数据表明，lls 1病变是由任何生物或非生物因子或内在代谢不平衡引起的细胞损伤事件触发的，只要叶组织发育有能力发展lls 1病变。然而，这些病变的持续扩大取决于光的可用性，注量率比光谱质量更重要。lls 1的双突变体分析与两个玉米突变体油黄和iojap，都损害光合作用和不能积累正常水平的叶绿素，表明这是由植物收获的光激发lls 1病变发展。叶绿体似乎是Its I细胞死亡的关键介质;它们的肿胀和扭曲发生在任何其他通常与死亡细胞相关的变化之前。与这些结果一致的是，LLS 1是叶绿体定位的蛋白质，其转录物仅在绿色组织中检测到。光依赖性lls 1病变的繁殖性质预示着与这些病变相关的细胞死亡是由移动的因子如活性氧化物质引起的。LLS 1可以防止反应性氧化物质的形成或用于去除细胞死亡介质，以维持叶绿体完整性和细胞存活。
We reported previously the isolation of a novel cell death-suppressing gene from maize (Zea mays) encoded by the Lls1 (Lethal leaf spot-1) gene. Although the exact metabolic function of LLS1 remains elusive, here we provide insight into mechanisms that underlie the initiation and propagation of cell death associated with lls1 lesions. Our data indicate that lls1 lesions are triggered in response to a cell-damaging event caused by any biotic or abiotic agent or intrinsic metabolic imbalance-as long as the leaf tissue is developmentally competent to develop lls1 lesions. Continued expansion of these lesions, however, depends on the availability of light, with fluence rate being more important than spectral quality. Double-mutant analysis of lls1 with two maize mutants oil-yellow and iojap, both compromised photosynthetically and unable to accumulate normal levels of chlorophyll, indicated that it was the light harvested by the plant that energized lls1 lesion development. Chloroplasts appear to be the key mediators of Its I cell death; their swelling and distortion occurs before any other changes normally associated with dying cells. In agreement with these results are indications that LLS1 is a chloroplast-localized protein whose transcript was detected only in green tissues. The propagative nature of light-dependent lls1 lesions predicts that cell death associated with these lesions is caused by a mobile agent such as reactive oxidative species. LLS1 may act to prevent reactive oxidative species formation or serve to remove a cell death mediator so as to maintain chloroplast integrity and cell survival.