异质水分环境下野牛草相连分株间光合同化物的生理整合及其调控

Photosynthate integration and regulation within clones of buffalograss under heterogeneous water supply

异质环境下,克隆植物通过生理整合机制使资源在分株间实现共享,提高了其对异质性环境的适应能力,具有重要的生态进化意义,研究生理整合机制及其调控机理可为进一步发掘克隆植物应用潜力提供理论依据。以野牛草3个相连分株为材料,对其中一个分株用30%聚乙二醇6000(PEG-6000)模拟水分胁迫,通过Hoagland营养液培养试验,研究了异质水分环境下光合同化物在野牛草相连分株间的生理整合及分株叶片与根系内源激素ABA与IAA含量的变化规律。结果表明,14C-光合同化物在克隆片断内存在双向运输,但以向顶运输为主,异质水分环境下,受胁迫分株光合同化物的输出率明显降低,而与其相邻分株合成的光合同化物向受胁迫分株方向运输率明显增加;异质水分环境下,各分株ABA含量均明显增加,但以受胁迫的分株叶片及根系ABA的含量增加幅度最大,各分株IAA含量较对照均显著下降(P<0.05),且以受胁迫分株IAA含量下降幅度最大;各分株叶片与根系ABA/IAA均显著提高(P<0.05),相邻分株ABA/IAA增加幅度低于受胁迫分株。异质水分环境影响野牛草克隆分株间光合同化物的生理整合,且ABA与IAA在分株间光合同化物运输与分配过程中具有重要的调节作用。

Physiological integration（translocation of resources） in clonal plants can improve their ability to cope with heterogeneous environments.Photosynthate integration may increases when one part of a clonal fragment（clone） is subjected to environmental stress such as drought and shading.However,few studies have examined mechanisms underlying physiological integration in clonal plants.The objective of this study was to examine the effects of water stress on the allocation patterns of endogenous hormones（ABA and IAA） and photosynthates within clones of the stoloniferous grass Buchloe dactyloides（buffalograss）.We measured abundance of ^14C-lableled photosynthates and concentrations of ABA and IAA in clonal fragments of buffalograss under homogeneous and heterogeneous water supply.Each clonal fragment consisted of three ramets,i.e.a relatively old,young and intermediate aged ramet.In the homogeneous treatments all three ramets of the fragments were grown without water stress and one ramet was labeled with ^14C.In the heterogeneous treatments one ramet of the clonal fragments was subjected to water stress by 30% PEG-6000 and the other two were not,and one ramet was also labeled with ^14 C.^14 C-photosynthate translocations were predominantly acropetal,i.e.from the older to the younger ramets.Import of ^14 C-photosynthates to the neighbor ramet was larger when the neighbor ramet was suffering from water stress（heterogeneous treatments） than when it was not（homogeneous treatments）.On the other hand,export of ^14C-photosynthates from the ramet subjected to water stress（heterogeneous treatments） decreased significantly as compared with the ramet not subjected to water stress（homogeneous treatments）.As compared with the homogeneous treatments,IAA contents in all the three ramets of the clonal fragments decreased under heterogeneous water treatments,whereas ABA contents and ABA/IAA increased.The results suggest that heterogeneous water supply can affect the carbohydrate integration among connected ramets of buffalograss,and that the stressed ramet can benefit greatly from its connected unstressed ramet.Because plant hormones play important roles in regulating developmental processes,signaling networks involved in plant responses to a wide range of biotic and abiotic stresses and balance of sink-source relationship,the changes in ABA and IAA in response to heterogeneous water supply suggest that endogenous hormones such as ABA and IAA may play an important role in controlling physiological integration of carbohydrates within connected ramets.