Leaf Senescence Is Accompanied by an Early Disruption of the Microtubule Network in Arabidopsis
Leaf Senescence Is Accompanied by an Early Disruption of the Microtubule Network in Arabidopsis
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DOI：
10.1104/pp.110.163402
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发表时间：
2010-12-01
期刊：
影响因子：
7.4
通讯作者：
Gardestrom, Per
中科院分区：
文献类型：
--
作者：
Keech, Olivier;Pesquet, Edouard;Gardestrom, Per
微管的动态组装和拆卸对细胞功能至关重要。虽然叶片衰老是一个有据可查的过程，MT细胞骨架在植物衰老过程中的作用仍然是未知的。在这里，我们表明，无论是自然叶片衰老和衰老的单独变暗的拟南芥（拟南芥）叶片伴随着早期退化的MT网络在表皮和叶肉细胞，而保卫细胞，不衰老，保留其MT网络。同样，完全黑暗的植物，不衰老，保留其MT网络。虽然编码微管蛋白亚基和捆绑/稳定MT相关蛋白（MAPs）MAP 65和MAP 70 -1的基因在自然衰老和黑暗诱导的衰老中均受到抑制，但我们发现编码MT不稳定蛋白MAP 18的基因受到强烈诱导。然而，诱导MAP 18基因的表达也观察到在叶完全黑暗的植物，表明它的表达是不足以诱导MT拆卸，更可能是一个Ca 2+依赖的信号传导机制的一部分。同样，基因编码的MT切断蛋白katanin p60和两个四个假定的监管katanin p80在黑暗中被抑制，但它们的表达并不相关的MT网络在叶片衰老过程中的降解。两者合计，这些结果突出了早期的皮质MT阵列在叶片衰老过程中的降解，并导致我们提出了一个模型，其中微管蛋白和MAP基因的抑制与MAP 18的诱导一起在MT拆卸衰老过程中发挥关键作用。
The dynamic assembly and disassembly of microtubules (MTs) is essential for cell function. Although leaf senescence is a well-documented process, the role of the MT cytoskeleton during senescence in plants remains unknown. Here, we show that both natural leaf senescence and senescence of individually darkened Arabidopsis (Arabidopsis thaliana) leaves are accompanied by early degradation of the MT network in epidermis and mesophyll cells, whereas guard cells, which do not senesce, retain their MT network. Similarly, entirely darkened plants, which do not senesce, retain their MT network. While genes encoding the tubulin subunits and the bundling/stabilizing MT-associated proteins (MAPs) MAP65 and MAP70-1 were repressed in both natural senescence and dark-induced senescence, we found strong induction of the gene encoding the MT-destabilizing protein MAP18. However, induction of MAP18 gene expression was also observed in leaves from entirely darkened plants, showing that its expression is not sufficient to induce MT disassembly and is more likely to be part of a Ca2+-dependent signaling mechanism. Similarly, genes encoding the MT-severing protein katanin p60 and two of the four putative regulatory katanin p80s were repressed in the dark, but their expression did not correlate with degradation of the MT network during leaf senescence. Taken together, these results highlight the earliness of the degradation of the cortical MT array during leaf senescence and lead us to propose a model in which suppression of tubulin and MAP genes together with induction of MAP18 play key roles in MT disassembly during senescence.