不同自然越冬阶段新疆野苹果花芽石蜡切片比较分析

Comparative Analysis of Flower Bud Anatomical Structure of Malus sieversii with Different Cold Resistance

观察比较新疆野苹果(Malus sieversii Ledeb.Roem)不同自然越冬阶段花芽抗寒性表达的形态学特征,分析新疆野苹果抗寒性形态学变化。本研究选取原生境和引种资源圃抗寒性相对强的小黄酸野苹果和抗寒性相对弱的香酸野苹果一年生枝条上饱满花芽为试验材料,采用石蜡切片法对两个种下类型新疆野苹果在休眠前期、休眠期、解休眠期3个不同越冬阶段分别采集花芽用苏木素和碘化钾染色观察淀粉粒大小和轴经、质壁分离程度等指标。结果表明,花芽细胞内淀粉粒轴径大小与抗寒性呈负相关,小黄酸野苹果花芽淀粉粒轴径在原生境不同越冬阶段分别为9.36、1.16、1.91μm,极显著小于香酸野苹果淀粉粒轴径,分别为10.95、2.88、5.42μm(P<0.01)。在引种资源圃不同越冬阶段小黄酸野苹果花芽淀粉粒轴径分别为6.03、1.37、2.92μm,极显著小于香酸野苹果淀粉粒轴径,分别为7.52、2.51、4.67μm(P<0.01)。小黄酸野苹果花芽在休眠期质壁分离现象最明显,原生质体孤立程度最大,在不同生境中质壁分离现象存在差异,在原生境不同越冬阶段质壁分离程度分别为53.2%、35.9%、49.0%,极显著大于香酸野苹果质壁分离程度,分别为49.0%、29.3%、40.0%(P<0.01);在引种资源圃不同越冬阶段小黄酸野苹果质壁分离程度分别为56.0%、23.8%、46.4%,极显著小于香酸野苹果质壁分离程度,分别为64.2%、41.3%、53.1%(P<0.01)。小黄酸野苹果在自然越冬不同阶段花芽细胞淀粉粒体积小,排列紧密,休眠期水解彻底,解除休眠期淀粉粒积累数量明显低于香酸野苹果;淀粉粒轴径极显著小于香酸野苹果;主花芽基部和花轴之间屏障组织可能是小黄酸野苹果阻止花轴细胞冰晶向花原基转移的特殊组织屏障。

To reveal the morphological mechanism of cold resistance expression in flower buds of Xinjiang wild apple at different natural overwintering stages.In this study,the full flower buds on the annual branches of the relatively strong microxanthic Malus sieversiif.luteolus and the relatively weak Malus sieversiif.aromaticus in the original habitat and introduced resource nursery were selected as experimental materials,and the paraffin section method was used to study the natural overwintering of the two species of Xinjiang wild apple in different stages.Floral bud samples were collected in early dormancy stage,dormancy stage and dormancy stage and stained with hematoxylin and potassium iodide to observe the anatomical characteristics.The axial diameter of starch grains in flower bud cells was negatively correlated with cold resistance.The axial diameths of starch grains from flower buds of Malus sieversiif.luteolus with strong cold resistance were 9.36μm,1.16μm and 1.91μm,respectively,which were significantly lower than those of starch grains from Malus sieversiif.aromaticus with weak cold resistance,which were 10.95μm,2.88μm and 5.42μm,respectively.The axial diameters of starch grains(6.03μm,1.37μm,2.92μm)were significantly lower than those of Malus sieversiif.aromaticus starch grains(7.52μm,2.51μm,4.67μm)at different overwintering stages in the introduced resource garden.The plasma wall separation of flower buds with strong cold resistance was the most obvious,and the isolation degree of protoplasts was the largest.The plasma wall separation was different in different habitats.In the original habitat,the separation degree of plasma wall was 53.2%,35.9% and 49.0%,respectively,which were 49.0%,29.3% and 40.0%,respectively.The separation degree of plasma wall in different wintering stages was 56.0%,23.8% and 46.4%,respectively,which were significantly lower than the separation degree of plasma wall in Malus sieversiif.aromaticus(64.2%,41.3% and 53.1%).The starch grains in flower bud cells of microflavic Malus sieversiif.luteolus with strong cold resistance were small in volume and closely arranged in different stages of natural wintering,and hydrolyzed completely in dormancy.The starch grains accumulated in dormancy were significantly lower than those in aromatic Malus sieversiif.aromaticus.The axial diameter of starch grains was significantly smaller than that of Malus sieversiif.luteolus.The barrier tissue between the base of the main flower bud and the flower axis may be a special barrier to prevent the transfer of ice crystals from the flower axis cells to the flower primordium.