生长素在蔗糖调节山定子幼苗根系亚低温响应和蔗糖代谢中的作用

The Role of Auxin in Sucrose Regulation of Sub-low Temperature Response and Sucrose Metabolism in the Roots of Malus baccata Borkh.Seedlings

根区低温影响果树根系代谢,不利于果树地上部的萌芽、展叶过程。前期研究发现,外源蔗糖可以增加亚低温下山定子根系内源吲哚乙酸(IAA)水平,但内源IAA在蔗糖缓解根系低温伤害中的生理作用尚不清楚。本试验以当年生山定子为试材,设置对照(CK),5℃根区亚低温(L),根区亚低温+90 mmol·L^(-1)蔗糖(L+S)处理和根区亚低温+蔗糖+300μmol·L^(-1)IAA合成抑制剂(L+S+BBo)处理,通过测定内源IAA含量、渗透调节物质含量、蔗糖代谢相关酶活性等指标和根系活力,探讨内源IAA在蔗糖调控山定子根系响应亚低温中的生理作用。结果表明:与L处理相比,L+S处理显著增加了内源IAA含量,促进了渗透调节物质的积累,根系活力增加,显著提高了山定子根系蔗糖代谢相关酶活性及其基因表达水平,增加了蔗糖、果糖、葡萄糖和山梨醇含量。与L+S处理相比,L+S+BBo处理显著降低根系IAA水平和根系活力,蔗糖和山梨醇含量显著降低,外源蔗糖对亚低温下根系蔗糖代谢的促进效果受到抑制。研究结果明确了内源IAA参与外源蔗糖诱导亚低温下山定子根系渗透调节物质和蔗糖代谢能力增加的过程,为苹果根系低温适应性研究提供了理论参考。

The low root-zone temperature affected the metabolism of roots,which was not conductive to the germination and leaf spreading process of fruit tree.We have found that exogenous sucrose could increase the endogenous IAA level of Malus baccata Borkh.roots under sub-low temperature,but the physiological role of endogenous IAA in alleviating root injury from low temperature by sucrose remains unclear.In this study,the seedlings of M.baccata were used as materials in this study.The treatments included the sub-low root-zone temperature(L,5 ℃),L+90 mmol·L^(-1)exogenous sucrose(L+S),L+sucrose+300 μmol·L^(-1)IAA synthesis inhibitor 4-biphenyl boric acid(L+S+BBo).We measured the contents of endogenous IAA,osmotic adjustment substance,sucrose metabolism related indexes and root activity to discuss the physiological role of endogenous IAA in exogenous sucrose regulating the response of roots to sub-low temperature.The results showed that:Compared with L treatment,L+S treatment significantly increased the contents of endogenous IAA,further promoted the accumulation of osmoregulatory substances,increased root activity,L + S treatment significantly improved the enzyme activity and expression levels of genes related to sucrose metabolism,and sucrose,fructose,glucose and sorbitol in roots were significantly increased.Compared with L+S treatment,L+S+BBo treatments significantly inhibited the level of endogenous IAA and root activity,reduced sucrose and sorbitol contents significantly.The promotion effects of exogenous sucrose on root sucrose metabolism at sub-low temperature were inhibited.These results indicated that endogenous IAA was involved in the process of increasing osmotic adjustment substance and sucrose metabolism ability of roots induced by exogenous sucrose at sub-low temperature,which provided a theoretical reference for the study on the adaptability of apple roots to low temperature.