外源水杨酸对低温下寒地冬小麦细胞超微结构的影响

Effects of Exogenous Salicylic Acid on Cell Ultrastructure of Winter Wheat under Cold Stress in Frigid Region

为探讨外源水杨酸(salicylic acid,SA)对低温下寒地冬小麦细胞超微结构的影响,选用东农冬麦1号为材料,在冬小麦幼苗长至三叶期时喷施1×10-4mol/L SA,以喷施等量蒸馏水作为对照,在越冬期自然降温条件下,分别于5℃、0℃、-10℃、-25℃时对分蘖节和茎取样,测定其丙二醛(MDA)含量,并用透射电镜观察其细胞的超微结构,统计返青率及分蘖节数。结果表明,外源SA减轻了低温对冬小麦膜系统造成的损害。对照组细胞仅在-25℃时出现了轻微的质壁分离;在-25℃各细胞器呈现轻微空泡化,线粒体外膜及核膜不清晰,但细胞核没有受到破坏。喷施SA后细胞核受损程度降低,核膜边缘清晰,线粒体结构完整清晰,内嵴数也略有增多,分蘖节的线粒体数目增多,仅在-25℃时核膜和线粒体的外膜不清晰,受到了轻微的破坏,但比对照组受损轻;前质体及淀粉粒数目增加(0℃以上);分蘖节中的液泡数目明显多于对照组。SA处理提高了返青率,并在返青后增加了分蘖节数。这说明SA处理可增强低温下细胞结构的稳定性,从而提高寒地冬小麦的低温适应性,从细胞学角度证实了外施适宜浓度的SA可增强寒地冬小麦的抗寒性。

In order to investigate the effects of exogenous salicylic acid （SA） on cell ultrastructure of winter wheat under low temperature, Dongnongdongmai No. 1 （the winter wheat cultivar in frigid region） was used as material and 1 x 10-4 mol/L SA was sprayed at seedlings growing to three leaves stages using spraying distilled water as control. In the winter natural cooling conditions, tillering nodes and stems were sampled, at 5 ℃, 0℃, -10℃, and -25 ℃, respectively, while Malondialdehyde （MDA） content was determined and the ultrastructure of the cells were observed by transmission electron microscopy, and the return rate and the number of tillering nodes were counted. The results showed that exogenous SA alleviated the damage caused by low temperature on membrane system. The cells in the control group appeared slight plasmolysis and slight vacuolization, mitochondrial membrane and nuclear membrane was not clear, but there was no damage to the nucleus only at -25 ℃. After the application of SA, nuclear damage degree was low, the nuclear and mitochondria membrane were clear, the number of cristae was slightly increased, the number of mitochondria increased in tillering nodes, Only at -25 ℃, nuclear membrane and mitochondrial membrane were not clear, and they were slightly damaged, but lighter than the control group; The number ofplastids and starch grains were increased （above 0℃）, and the number of vacuoles in tillering nodes was significantly more than that in the control group. The return rate and tillering nodes number were increased after reviving by exogenous SA. This showed that SA pretreatment could enhance the stability of the celt structure at low temperature, so as to improve the adaptability to low temperature of winter wheat in cold region, from the view of cytology it was confirmed the application of suitable concentration of SA could enhance the cold resistance of winter wheat in cold area.