Changes in the synthesis of rubisco in rice leaves in relation to senescence and N influx
Changes in the synthesis of rubisco in rice leaves in relation to senescence and N influx
复制标题
DOI：
10.1093/aob/mcm270
复制
发表时间：
2008-01-01
期刊：
影响因子：
4.2
通讯作者：
Makino, Amane
中科院分区：
文献类型：
--
作者：
Imai, Kazuhiro;Suzuki, Yuji;Makino, Amane
背景：叶片中合成的核酮糖-1，5-二磷酸羧化酶/加氧酶(Rubisco，EC 4.1.1.39)的量与叶片一生中氮素的内流密切相关。在膨大过程中，Rubisco合成和N内流在幼叶中最为活跃，而在衰老叶中则非常有限。然而，即使在非常衰老的叶片中，如果增加N内流，是否可以观察到Rubisco的合成，还没有确定。本研究首次探讨了RBC和RbcL mRNA含量以及单位叶质量的Rubisco合成与叶片衰老的关系。然后，在衰老后期摘除叶片，以检测在非常衰老的叶片中，增加N输入是否会重新刺激Rubisco的合成。方法在第8片叶片衰老的早期(完全展开)、中期和后期(分别在完全展开后8d和16d)向水稻植株供应不同浓度的N(1和4 mm)。为促进氮素向第8叶的流入，除第8叶外，主茎上除第8叶外的所有叶片均被摘除，植株接受4 mM N处理。关键结果表明，随着叶片衰老，Rbcs和rbcL mRNAs的合成、rbcL和rbcL mRNAs的翻译效率均随叶片衰老而降低。结论虽然Rubisco合成、Rbcs和rbcL mRNAs随叶片衰老而减少，但衰老后期叶片具有主动合成Rubisco的潜力，增加了N内流。
Background The amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) synthesized in a leaf is closely correlated with N influx into the leaf throughout its lifetime. Rubisco synthesis and N influx are most active in the young leaf during expansion, but are very limited in the senescent leaf. However, it is not established whether Rubisco synthesis can be observed if N influx is increased, even in a very senescent leaf. This study first investigated changes in the relationships between rbcS and rbcL mRNA contents and Rubisco synthesis per unit of leaf mass with leaf senescence. Next, leaves were removed during late senescence, to examine whether Rubisco synthesis is re-stimulated in very senescent leaves by an increase in N influx.Methods Different N concentrations (1 and 4 mM) were supplied to Oryza sativa plants at the early (full expansion), middle and late stages (respectively 8 and 16 d after full expansion) of senescence of the eighth leaf. To enhance N influx into the eighth leaf 16 d after full expansion, all leaf blades on the main stem, except for the eighth leaf, and all tillers were removed and plants received 4 mM N (removal treatment).Key Results Rubisco synthesis, rbcS and rbcL mRNAs and the translational efficiencies of rbcS and rbcL mRNAs decreased with leaf senescence irrespective of N treatments. However, in the removal treatment at the late stage, they increased more strongly with an increase in N influx than in intact plants.Conclusions Although Rubisco synthesis and rbcS and rbcL mRNAs decrease with leaf senescence, leaves at the late stage of senescence have the potential actively to synthesize Rubisco with an increase in N influx.