Hoch G, Keel S G
Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland.
Plant Biol (Stuttg). 2006 Sep;8(5):606-14. doi: 10.1055/s-2006-924279. Epub 2006 Aug 1.
The pathways of currently fixed carbon in fruit bearing branchlets were investigated in two temperate forest tree species (CARPINUS BETULUS and FAGUS SYLVATICA), which differ in texture of their vegetative infructescence tissues (leaf-like in CARPINUS vs. woody in FAGUS). During late spring, (13)C pulse-labelling was conducted on girdled, defoliated, girdled plus defoliated and untreated fruiting branchlets of mature trees IN SITU, to assess changes in C relations in response to the introduced C source-sink imbalances. At harvest in early August, 75 - 100 % of the recovered (13)C label was bound to infructescences (either fruits or vegetative infructescence tissue), revealing them as the prime C sinks for current photoassimilates. Leaves on girdled branchlets were not stronger labelled than on ungirdled ones in both species, indicating no upregulation of the leaves' photosynthetic capacity in response to the prevention of phloemic transport, which was also supported by measurements of light saturated photosynthesis. In contrast, (13)C labels tended to be higher after complete defoliation in the vegetative infructescence tissues of CARPINUS, suggesting enhanced net photosynthesis of green infructescence parts as compensation for the loss of regular leaves. The total labelling-derived (13)C content of whole infructescences was very similar between foliated and defoliated CARPINUS branchlets. Cupulae of FAGUS, on the other hand, remained almost unlabelled on defoliated branchlets, indicating the photosynthetic inactivity of this woody infructescence tissue. Consequently, CARPINUS still produced relatively high fruit masses on girdled plus defoliated branchlets, while in FAGUS fruit development ceased almost completely at this most severe treatment. Our results highlight that green vegetative infructescence tissue assimilates substantial amounts of C and can partly substitute regular leaves as C sources for successful fruit development.
在两种温带森林树种（欧洲鹅耳枥和欧洲山毛榉）中研究了结果小枝中当前固定碳的途径，这两种树种的营养性果序组织质地不同（欧洲鹅耳枥的为叶状，而欧洲山毛榉的为木质）。在晚春时节，对成熟树木原位的环剥、去叶、环剥加去叶和未处理的结果小枝进行了¹³C脉冲标记，以评估碳关系对引入的碳源 - 碳库失衡的响应变化。在八月初收获时，回收的¹³C标记中有75 - 100%与果序（果实或营养性果序组织）结合，表明它们是当前光合产物的主要碳库。在这两个树种中，环剥小枝上的叶片标记并不比未环剥小枝上的更强，这表明叶片光合能力不会因韧皮部运输受阻而上调，光饱和光合作用的测量结果也支持了这一点。相反，在欧洲鹅耳枥营养性果序组织中，完全去叶后¹³C标记往往更高，这表明绿色果序部分的净光合作用增强，以补偿正常叶片的损失。有叶和去叶的欧洲鹅耳枥小枝上整个果序的总标记衍生¹³C含量非常相似。另一方面，欧洲山毛榉的壳斗在去叶小枝上几乎没有标记，表明这种木质果序组织没有光合活性。因此，在环剥加去叶的小枝上，欧洲鹅耳枥仍能产生相对较高的果实质量，而在欧洲山毛榉中，在这种最严重的处理下果实发育几乎完全停止。我们的结果突出表明，绿色营养性果序组织能同化大量碳，并且可以部分替代正常叶片作为成功果实发育的碳源。
Zotero 插件