Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases...Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases rice yield an d grain numbers. High concentration depresses grain formation (9～30 mg·L -1 ) and root elongation (1.5～30 mg·L -1). No significant influence on str aw dry weight was found over the whole concentration range except the 0.05 mg·L -1 treatment. With the increase of La concentration from 0.05 to 0.75 mg· L -1, catalase (CAT) activity in the first fully expandeing leaves and root s decreases. When La concentration is greater than 0.75 mg·L -1 or less than 9 mg·L -1, it significantly decreases superoxide dismutase activity ( SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promotin g effect on rice growth and reduction effect of ·O- 2 were discussed.展开更多
Split-root system（SRS） approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic（shoo...Split-root system（SRS） approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic（shoot origin）versus local（root/nodule origin） regulation mechanisms. This type of approach is particularly useful when studying the complex regulatory mechanisms governing the symbiosis established between legumes and Rhizobium bacteria. The current work provides an overview of the main insights gained from the application of SRS approaches to understand how nodule number（nodulation autoregulation） and nitrogen fixation are controlled both under non-stressful conditions and in response to a variety of stresses. Nodule number appears to be mainly controlled at the systemic level through a signal which is produced by nodule/root tissue, translocated to the shoot, and transmitted back to the root system, involving shoot Leu-rich repeat receptor-like kinases. In contrast, both local and systemic mechanisms have been shown to operate for the regulation of nitrogenase activity in nodules. Under drought and heavy metal stress, the regulation is mostly local,whereas the application of exogenous nitrogen seems to exert a regulation of nitrogen fixation both at the local and systemic levels.展开更多
文摘Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases rice yield an d grain numbers. High concentration depresses grain formation (9～30 mg·L -1 ) and root elongation (1.5～30 mg·L -1). No significant influence on str aw dry weight was found over the whole concentration range except the 0.05 mg·L -1 treatment. With the increase of La concentration from 0.05 to 0.75 mg· L -1, catalase (CAT) activity in the first fully expandeing leaves and root s decreases. When La concentration is greater than 0.75 mg·L -1 or less than 9 mg·L -1, it significantly decreases superoxide dismutase activity ( SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promotin g effect on rice growth and reduction effect of ·O- 2 were discussed.
基金partially funded by the Spanish National Research and Development Program (AGL2011-30386-CO2-1 and AGL2011-23738)
文摘Split-root system（SRS） approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic（shoot origin）versus local（root/nodule origin） regulation mechanisms. This type of approach is particularly useful when studying the complex regulatory mechanisms governing the symbiosis established between legumes and Rhizobium bacteria. The current work provides an overview of the main insights gained from the application of SRS approaches to understand how nodule number（nodulation autoregulation） and nitrogen fixation are controlled both under non-stressful conditions and in response to a variety of stresses. Nodule number appears to be mainly controlled at the systemic level through a signal which is produced by nodule/root tissue, translocated to the shoot, and transmitted back to the root system, involving shoot Leu-rich repeat receptor-like kinases. In contrast, both local and systemic mechanisms have been shown to operate for the regulation of nitrogenase activity in nodules. Under drought and heavy metal stress, the regulation is mostly local,whereas the application of exogenous nitrogen seems to exert a regulation of nitrogen fixation both at the local and systemic levels.
