The changes of leaf carbohydrate contents as a regulator of autophagic degradation of chloroplasts via rubisco-containing bodies during leaf senescence
The changes of leaf carbohydrate contents as a regulator of autophagic degradation of chloroplasts via rubisco-containing bodies during leaf senescence
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DOI：
10.4161/psb.6.5.14949
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发表时间：
2011-01-01
影响因子：
2.9
通讯作者：
Ishida, Hiroyuki
中科院分区：
文献类型：
--
作者：
Izumi, Masanori;Ishida, Hiroyuki
自噬是细胞质成分空泡降解的细胞内过程，对饥饿过程中的营养循环具有重要意义。叶绿体可以通过含有Rubisco小体的球形小体(RCB)通过自噬的方式部分地被动员到液泡中。虽然叶绿体含有约80%的叶片总氮，是循环利用的主要碳源和氮源，但叶片营养状况与RCB产生之间的关系尚不清楚。我们分析了营养因子对拟南芥叶片中RCB出现的影响，并推测通过RCB对叶绿体的自噬降解与叶片中的碳状态密切相关，而与自噬中的氮状态无关。碳水化合物在叶片衰老过程中产生RCB的重要性可以进一步论证。在氮素限制衰老过程中，随着叶片碳水化合物的积累，RCB的产生受到强烈抑制。在叶片的整个生命周期中，RCB的产量随着叶片展开和衰老的进程而增加，而在衰老后期的叶片中RCB的产量下降，碳水化合物、葡萄糖和果糖的积累显著。这些结果表明，RCB的产生可能受到诱导衰老和自然衰老过程中叶片碳状态的控制。
Autophagy is an intracellular process for the vacuolar degradation of cytoplasmic components and is important for nutrient recycling during starvation. Chloroplasts can be partially mobilized to the vacuole by autophagy via spherical bodies named Rubisco-containing bodies (RCBs). Although chloroplasts contain approximately 80% of total leaf nitrogen and represent a major carbon and nitrogen source for recycling, the relationship between leaf nutrient status and RCB production remains unclear. We analyzed the effects of nutrient factors on the appearance of RCBs in Arabidopsis leaves and postulated that a close relationship exists between the autophagic degradation of chloroplasts via RCBs and leaf carbon status but not nitrogen status in autophagy. The importance of carbohydrates in RCB production during leaf senescence can be further argued. During nitrogen-limited senescence, as leaf carbohydrates were accumulated, RCB production was strongly suppressed. During the life span of leaves, RCB production increased with the progression of leaf expansion and senescence, while the production declined in late senescent leaves with a remarkable accumulation of carbohydrates, glucose and fructose. These results suggest that RCB production may be controlled by leaf carbon status during both induced and natural senescence.