低磷胁迫下不同杉木家系根系H^+流动态变化

Dynamic changes of H^+ flow in roots of Chinese fir under low phosphorous stress conditions

通过分析不同杉木家系在不同供磷处理下根系H^+流变化规律,探讨根系H^+流与杉木适应低磷胁迫调控的关系,为揭示磷高效利用杉木适应低磷胁迫的内在机制提供科学依据。以前期筛选出的不同磷利用效率杉木家系M28与M32为研究对象,通过设计3个供磷处理[正常供磷(H-P),31 mg·L^-1;中度缺磷(L-P),16 mg·L^-1;重度缺磷(N-P),0 mg·L^-1]和3个时间处理梯度(3、8、15 d)室内水培试验,并利用非损伤微测技术(NMT)分别测定两个家系在不同供磷处理和不同时间处理梯度下完整根系及不同部位的H^+动态变化规律。结果表明:不同杉木家系完整根系H^+全程表现为内流,但二者H^+流变化存在显著差异,M28完整根系H^+吸收表现为8 d>15 d>3 d,M32在不同时间处理下H^+的变化无显著差异(P>0.05)。结合根系不同部位H^+流向分析可得,M28与M32仅在L-P和N-P处理3 d时表现出少量H^+外排现象,其中M28对外界磷环境的感应比M32更为敏感,在L-P处理下就发生H^+外排现象,M32在N-P处理才发现H^+外排。随着时间推移,在处理8、15 d后,两个杉木家系均未观测到H^+的外排,可见低磷胁迫下根系H^+外排是一种应激反应。不同杉木家系根系H^+流在低磷环境下表现出不同的适应性变化,其中M28根系的H^+流对外界磷环境的改变更为敏感。

This paper analyzes the change of H^+flow in the roots of two different clones of the Chinese fir(Cunninghamia lanceolata)under different levels of phosphorus,discusses the relationship between root H^+flow and adaptation of C.lanceolata to low-phosphorus stress,and provides a scientific basis for the internal mechanism of high-efficiency phosphorus utilization in C.lanceolata under low-phosphorus stress conditions.Two C.lanceolata clones,M28 and M32,which display different phosphorus utilization efficiencies,were tested under three phosphorus supply levels reflecting normal supply,moderate deficiency,and severe deficiency over three time periods(3,8,and 15 d).The results showed significantly greater H^+inflow throughout the root system of M28 clone,but no significant difference in H^+excretion between the two clones over the different treatment time periods.The M28 clone was more sensitive to phosphorus stress than M32,as demonstrated by reduced H^+efflux under moderate phosphorus deficiency stress conditions,whereas M32 maintained H^+low efflux even under severe phosphorus deficiency stress conditions over the shortest time interval.For both the longer time periods,H^+efflux ceased,indicating that H^+efflux from the roots is a stress response to low-phosphorus conditions.The results show that different genotypes of C.lanceolata are capable of different levels of adaptability to conditions of low phosphorus.The H^+flow in the roots of the clone with high phosphorus utilization efficiency M28 was more sensitive to the change in phosphorus inputs,demonstrating that H^+flow in the roots of C.lanceolata is a stress response to changes in external levels of phosphorus.