The structural and photosynthetic characteristics of the exposed peduncle of wheat (Triticum aestivum L.): an important photosynthate source for grain-filling.
The structural and photosynthetic characteristics of the exposed peduncle of wheat (Triticum aestivum L.): an important photosynthate source for grain-filling.
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DOI：
10.1186/1471-2229-10-141
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发表时间：
2010-07-11
影响因子：
5.3
通讯作者：
Zhang B
中科院分区：
文献类型：
--
作者：
Kong L;Wang F;Feng B;Li S;Si J;Zhang B
在小麦(Triticum Aestivum L)中，旗叶被认为是籽粒生长的主要同化物来源，而花序梗通常被认为是运输器官。因此，裸露的花序梗的光合作用特性被忽略了。在本研究中，我们研究了小麦籽粒个体发育过程中裸露的穗梗的解剖特征，并比较了裸露的穗梗和旗叶的叶绿体超微结构、光系统II(PSII)量子产量和磷酸烯醇式丙酮酸羧化酶(PEPCase；EC 4.1.1.31)的活性。透射电子显微镜观察表明，在灌浆阶段1、2和3，旗叶和裸露的花序梗叶绿体发育良好，有大量的基粒堆叠。在裸露的花序梗中，构成类囊体的膜非常明显和丰富，而在旗叶中，类囊体膜在阶段4急剧破裂，在阶段5完全解体。PSII量子效率分析表明，光合作用效率在阶段1、2和3保持不变，然后在两个器官中都下降。然而，旗叶的下降幅度比裸露的花序梗更明显。酶活性测定表明，在第1、2期，露花序梗的PEPCase活性低于旗叶，而在第3、4、5期，露花花序梗的PEPCase活性高于旗叶，其中第5期的差异尤其显著。我们的结果表明，裸露的花序梗是一个光合作用活跃的器官，产生光合作用产物，因此对籽粒生长起着至关重要的作用，特别是在灌浆后期。
In wheat (Triticum aestivum L), the flag leaf has been thought of as the main source of assimilates for grain growth, whereas the peduncle has commonly been thought of as a transporting organ. The photosynthetic characteristics of the exposed peduncle have therefore been neglected. In this study, we investigated the anatomical traits of the exposed peduncle during wheat grain ontogenesis, and we compared the exposed peduncle to the flag leaf with respect to chloroplast ultrastructure, photosystem II (PSII) quantum yield, and phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) activity. Transmission electron microscope observations showed well-developed chloroplasts with numerous granum stacks at grain-filling stages 1, 2 and 3 in both the flag leaf and the exposed peduncle. In the exposed peduncle, the membranes constituting the thylakoids were very distinct and plentiful, but in the flag leaf, there was a sharp breakdown at stage 4 and complete disintegration of the thylakoid membranes at stage 5. PSII quantum yield assays revealed that the photosynthetic efficiency remained constant at stages 1, 2 and 3 and then declined in both organs. However, the decline occurred more dramatically in the flag leaf than in the exposed peduncle. An enzyme assay showed that at stages 1 and 2 the PEPCase activity was lower in the exposed peduncle than in the flag leaf; but at stages 3, 4 and 5 the value was higher in the exposed peduncle, with a particularly significant difference observed at stage 5. Subjecting the exposed part of the peduncle to darkness following anthesis reduced the rate of grain growth. Our results suggest that the exposed peduncle is a photosynthetically active organ that produces photosynthates and thereby makes a crucial contribution to grain growth, particularly during the late stages of grain-filling.
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影响因子：
2.7
作者：
Wang, ZM;Wei, AL;Zheng, DM
通讯作者：
Zheng, DM
影响因子：
4.2
作者：
Wardlaw, IF
通讯作者：
Wardlaw, IF
影响因子：
6.9
作者：
Hetherington, SE;Smillie, RM;Davies, WJ
通讯作者：
Davies, WJ
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作者：
Kutík, J;Kocová, M;Körnerová, M
通讯作者：
Körnerová, M
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6.9
作者：
Wu, Keqiang;Zhang, Lin;Chaikam, Vijaya
通讯作者：
Chaikam, Vijaya