外源钙离子对NaCl胁迫下油茶花粉萌发的影响

Effects of exogenous Ca^(2+) on pollen germination of Camellia oleifera under NaCl stress

【目的】探讨NaCl对油茶花粉生活力、花粉萌发和花粉管生长的影响,以及Ca^(2+)是否有缓解作用,旨在探索在盐渍化地区引种油茶的可能性,为油茶的引种和栽培提供参考资料。【方法】以油茶‘华硕’花粉为试验材料,采用MTT染色法和花粉液体培养法,研究NaCl胁迫以及在NaCl胁迫环境中添加Ca^(2+)后对油茶花粉生活力、萌发率和花粉管生长的影响。【结果】1)NaCl对油茶花粉生活力、花粉萌发和花粉管伸长均有抑制作用,且抑制效果随NaCl浓度的提高而增强,而高浓度NaCl可完全抑制花粉萌发。20 mM NaCl的抑制效果显著(P<0.05),此时花粉生活力和花粉萌发率分别为36.22%和42.84%,分别是CK的49.97%和57.33%,花粉管长度为23.75μm,是CK的73.54%。在NaCl胁迫环境中,部分花粉管的顶端有膨大现象。2)在20 mM NaCl的胁迫下,外源Ca^(2+)对花粉生活力有抑制作用,但能部分缓解NaCl对油茶花粉萌发和花粉管伸长的抑制作用。2 mM Ca^(2+)对花粉萌发率的缓解效果最佳,此时花粉萌发率显著提高,为60.5%,而Ca^(2+)浓度超过2 mM时,花粉萌发率显著下降,维持在29%左右,出现抑制作用。花粉管长度随着Ca^(2+)浓度的增加而缓慢增长,25 mM Ca^(2+)对花粉管伸长的促进作用最明显,此时花粉管最长,为35.05μm。当Ca^(2+)浓度超过3 mM时,在刚萌发出来的花粉管或者较短的花粉管中顶端破裂现象严重。【结论】在花粉的离体培养过程中,NaCl会对油茶花粉生活力、花粉萌发和花粉管伸长造成胁迫,所以,在油茶的栽培和管理过程中,应避免将油茶处在盐胁迫环境中。Ca^(2+)参与了油茶花粉适应盐环境的过程,可为提高油茶耐盐性的研究奠定理论基础。

【Objecctive】To explore the effects of NaCl on pollen viability,pollen germination and pollen tube growth of Camellia oleifera,and whether Ca^(2+)can alleviate it,in order to explore the possibility of introducing C.oleifera to salinized areas and provide reference for its introduction and cultivation.【Method】Using C.oleifera‘Huashuo’pollen as experimental material,the effects of NaCl stress and the addition of Ca^(2+)in the NaCl stress environment on the pollen viability,germination rate and pollen tube growth of C.oleifera were studied by MTT staining and pollen liquid culture.【Result】1)NaCl can inhibit the pollen vitality,pollen germination and pollen tube elongation of C.oleifera.The Inhibition effects increases with the increase of NaCl concentration,while high concentration NaCl can completely inhibit pollen germination.The inhibition effect of 20 mM NaCl is significant(P<0.05).At this time,the pollen viability and pollen germination rate are 36.22%and 42.84%respectively,which is 49.97%and 57.33%of CK respectively,and the pollen tube length is 23.75μm,which is 73.54%of CK.The tip of some pollen tubes expands under the NaCl stress environment.2)Under the stress of 20 mM NaCl,exogenous Ca^(2+)can inhibit pollen viability,but it can partially alleviate the inhibition of NaCl on pollen germination and pollen tube elongation of C.oleifera.2 mM Ca^(2+)has the best alleviation effect on the pollen germination and the pollen germination rate significantly increased to 60.5%.When the concentration of Ca^(2+)is more than 2 mM,pollen germination is inhibited and the rate of pollen germination decreases significantly,maintained at about 29%.The length of pollen tube increases slowly with the increase of Ca^(2+)concentration.25 mM Ca^(2+)has the most obvious effect on the elongation of pollen tube,which is 35.05μm.However,when the concentration of Ca^(2+)is more than 3 mM,the top of the newly germinated pollen tubes or the shorter pollen tubes bursts seriously.【Conclusion】In the process of pollen culture in vitro,NaCl can cause stress on pollen viability,pollen germination and pollen tube elongation of C.oleifera.So,during the cultivation and management of C.oleifera,it should be avoided to put C.oleifera in salt stress environment.Ca^(2+)participates in the process of its pollen adapting to salt environment,which can lay the theoretical foundation for the study of improving the salt tolerance of C.oleifera.