盐胁迫条件下转多基因库安托杨根尖离子流变化

摘要

[Objective]Intracellular K + /Na + homeostasis is crucial for cell metabolism and is considered to be a key component of salinity tolerance in plants.[Method]The plant height,dry biomass of roots and net fluxes of Na +,K +,H +from apex roots ( using non-invasive micro-test technology ) were investigated in the multiple transgenic Populus × euramericana‘Guariento’(named D5-21,D5-20)and non-transgenic species(named D5-0)under 100 mmol·L-1 NaCl stress at three different period. [Result]Growth data indicated that: compared with control,all of the three lines had a lower height after 7 days of salt stress treatment,but no significant declined; But after 15 days treatment,the plant height of D5-20,D5-0 was declined significantly;when the treatment extended to 30 days,the height of three poplar lines and their amount of dry matter in root were significantly reduced,the D5-0 and D5-21 remained only 50% of dry matter compare with normal water supply conditions,these data showed that salt stress inhibited the growth of poplar roots seriously; meanwhile,the phenotypic changes showed that,compare to D5-0,D5-21,D5-20 were under lower danger level,had higher height and more dry matter in root after treatment. Na + fluxes results showed that: there is a significant change of each line roots’Na + fluxes after 7 days of stress treatment,but the magnitude is too small; D5-21,D5-20 roots’Na + extruding capacity is 1. 8 times of D5-0 after 15 days of stress treatment; D5-21,D5-20 roots’Na + extruding capacity is 1. 6 times of D5-0 after 30 days of stress treatment. K + fluxes results showed that as stress time continues, D5-0,D5-21 roots’K +effluxing increased,D5-20 is then decreased,but the trends are quite different,D5-0 roots’K +effluxing capacity is 1. 7 times of D5-21 and 2. 1times of D5-20 after 30 days of stress treatment. H + fluxes results showed: as stress time continues,all the three lines roots’H +influxing increased,but the increasing of D5-21、D5-20 is significantly greater than D5-0; D5-21,D5-20 roots’H + influxing capacity is 1. 6 times and 1. 2 times of D5-0 after 30 days of stress treatment. So,whether it is short-term (7 days) ,medium-term (15 days) or long term (30 days) salt stress treatment,transgenic lines D5-21,D5-20 exhibited a higher capacity to extrude Na +,meanwhile,the influx of H +had a significant increasing,and a less reduction of K +versus D5-0,Thus,the transgenic poplar species can avoid excessive cytoplasmic Na + accumulation by extruding Na +,and decreased the K + leakage from cytoplasmic,and these two measuremtnts are helpful to maintain K + /Na +homeostasis. Therefore,transgenic poplar species implied an increased salt tolerance and growth accumulation,this will provide a new evidence for salt tolerance screening of transgenic trees.[Conclusion]JERF36 gene is a ERF transcription factor that can activates the expression of downstream stress resistance genes,and is closely related with plants resistance. So the relationship between JERF36 gene and the gene expression involving in the transport of Na +,H +,K + ions deserves to take a further study.%【目的】细胞质内 K +/Na +平衡对细胞的代谢起重要作用，同时也被认为是植物抵御盐胁迫的重要部分。【方法】以转多基因库安托杨株系 D5－21、D5－20及非转基因受体 D5－0为材料，研究100 mmol·L －1 NaCl处理的不同时期(7，15，30天)各杨树株系的株高、根部干物质量、根尖离子流( Na +、K +、H +)的动态变化(利用非损伤微测技术)。【结果】生长数据表明：与正常供水条件相比，7天盐胁迫处理后，3个株系的株高降低，但不显著；15天处理后，D5－20，D5－0株高显著降低；30天处理后，3个株系株高和根部干物质量均显著降低，D5－0，D5－21的根干物质量只有正常供水条件下的一半，说明盐胁迫严重抑制杨树根的生长；但表型变化表明盐胁迫下D5－21， D5－20植株的受害程度更小，并且株高和根部干物质量均高于 D5－0。Na +流测定结果表明：7天盐胁迫处理后，各株系根尖的 Na +流虽与对照相比有显著变化，但变化幅度均较小；15天盐胁迫处理后，D5－21，D5－20根尖 Na +外排能力均是 D5－0的1.8倍；30天处理后，D5－21，D5－20根尖 Na +外排能力均是 D5－0的1.6倍。K +流测定结果表明：D5－0，D5－21根尖 K +外流流速随着胁迫时间延长而增大，D5－20则是先增大后减小，但3个株系变化趋势差异较大，30天处理时，D5－0的流速已是D5－21，D5－20的1.7倍和2.1倍。H +流测定结果表明：虽然与 D5－21， D5－20一样，D5－0的 H +内流值随着胁迫时间延长而增大，但 D5－21，D5－20的增幅明显大于D5－0，30天处理时，二者的 H +流速是 D5－0的1.6倍和1.2倍。因此，不论是短期(7天)、中期(15天)还是长期(30天)盐胁迫处理，与非转基因株系相比，转基因株系 D5－21，D5－20都具有更强的 Na +外排和 H +内流能力，且 K +的外流幅度远低于D5－0，说明转基因株系可通过将根尖细胞质中过多的 Na +主动外排、并减少根尖细胞中 K +的损失，维持胞质中的适宜的 K +/Na +，转基因株系的耐盐性提高，从而有利于转基因株系的生长积累，这将为转基因林木的耐盐性筛选提供新的参考依据。【结论】JERF36基因属于 ERF类转录因子，它可激活植物中下游抗逆相关基因的表达，与植物的抗逆性密切相关，因此未来可研究盐胁迫下转多基因库安托杨中 JERF36基因与 Na +，K +，H +这3种重要离子的转运所涉及的相关基因表达的关系。