Heterotrophic gain of carbon from hosts by the xylem-tapping root hemiparasite Olax phyllanthi (Olacaceae)
Heterotrophic gain of carbon from hosts by the xylem-tapping root hemiparasite Olax phyllanthi (Olacaceae)
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DOI：
10.1007/bf00328740
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发表时间：
1996-02
期刊：
影响因子：
2.7
通讯作者：
K. U. Tennakoon;J. S. Pate
中科院分区：
文献类型：
--
作者：
K. U. Tennakoon;J. S. Pate
根半寄生灌木叶下夹竹桃（Olax phyllanthi（Labill）R.Br.）利用C3和C4寄主的碳同位素（δ 13 C）判别法以及寄主和寄生虫木质部汁液和干物质的C：N比，对100个不同寄主和寄生虫进行了分析。根据δ 13 C值计算的两种非天然C4寄主（马齿苋和尾穗苋）对Olax的异养效益（H）分别为30%和19%，而根据寄主木质部汁液的C：N比和Olax干物质的C和N增量计算的H分别为13%和15%。硝酸盐是上述物种盆栽氮的来源，基于C：N比的估计假设Olax积累的所有N来自宿主吸收的硝酸盐。相等的估计HforOlax，生长在无氮盆栽与本地N2固定主机相思littorea作为其唯一的N源，表明63%和51%的依赖于主机碳时，评估木质部汁液组成的主机寄生虫分别。比较木质部汁液溶质ofOlax和一系列的合作伙伴主机表明显着的选择性吸器吸收和转移的硝酸盐，氨基化合物，有机酸和糖。C和无机和有机形式的N在木质部的绝对水平之间的主机的变化可能产生的影响进行了讨论，在有关的证据更好的生长性能ofOlaxonAcacia littorea和其他N2固定豆类比非固定器。
Heterotrophic gains of carbon from various host species by the root hemiparasitic shrubOlax phyllanthi(Labill) R.Br. were assessed using techniques based on carbon isotope discrimination (δ13C) on C3 and C4 hosts and C:N ratios of xylem sap and dry matter of host and parasite. Heterotrophic benefits (H) toOlaxbased on δ13C values were 30% and 19% from two nonnative C4 hosts (Portulaca oleraceaandAmaranthus caudatusrespectively) compared with 13% and 15% from these hosts when computed on the basis of C:N ratios of host xylem sap and C and N increments ofOlaxdry matter. Nitrate was the source of N available to pot cultures of the above species and estimates based on C:N ratios assumed that all N accumulated byOlaxhad come from nitrate absorbed by the host. Equivalent estimates ofHforOlax, grown in nitrogen-free pot culture with the native N2-fixing hostAcacia littoreaas its sole source of N, indicated 63% and 51% dependence on host carbon when assessed in terms of xylem sap composition of host parasite respectively. Comparisons of xylem sap solutes ofOlaxand a range of partner hosts indicated marked selectivity in haustorial uptake and transfer of nitrate, amino compounds, organic acids and sugars. Possible implications of variations between hosts in absolute levels of C and inorganic and organic forms of N in xylem are discussed in relation to evidence of much better growth performance ofOlaxonAcacia littoreaand other N2-fixing legumes than on non-fixers.