中文摘要：

【目的】通过研究枳橙砧木对硼胁迫的反应,揭示缺硼对柑橘砧木细根根尖成熟区和中部功能叶解剖结构的影响。【方法】采用营养液的方式培养枳橙砧木幼苗,试验设置2个处理,分别为不施硼（-B）处理和施硼（硼酸含量为10μmol·L^-1,＋B）处理。取枳橙砧木中上部的幼嫩叶片和细根根尖成熟区部分为观察材料,采用石蜡切片并结合透射电镜（TEM）,研究缺硼对枳橙砧木解剖结构和亚细胞微观结构的影响。【结果】缺硼导致根部的皮层薄壁细胞数目减少且排列疏松紊乱、细胞变形破裂,细胞间隙增大;同时,细胞质出现解体并伴随多种细胞器消失,细胞壁厚度明显增加;而加硼处理的植株根部薄壁细胞的形态则表现正常,细胞大小均一,排列紧密,细胞间隙小;加硼处理的维管束细胞着色较深,形态正常,维管束的结构层次清晰,呈圆周状均匀分散在中央髓部周围。硼胁迫严重抑制了根部维管束发育,使其分化不明显、细胞体积小且排列无规则。缺硼的叶片纵切面加厚且不均匀,海绵组织细胞变形破裂,细胞间出现大的空缺,细胞数目多且体积大,使得海绵组织在叶肉中所占的比例明显增加;加硼处理的叶片纵切面各处厚度均一,表皮细胞形状规则排列紧密,栅栏组织细胞呈长圆柱形,细胞单层垂直分布表皮细胞之下,细胞排列整齐紧密;栅栏组织下面的海绵组织细胞结构完整,排列疏松,细胞间形成大小均匀的气腔。另外,缺硼导致叶片细胞中积累较多淀粉粒,叶片可溶性糖与淀粉含量比加硼时分别提高35.3%和66.7%,而加硼处理的叶片细胞中则没有观察到有明显的淀粉粒存在;缺硼叶片的维管束中薄壁细胞出现变形、破裂等现象。【结论】缺硼破坏细胞内部结构,造成细胞壁加厚,叶片细胞内淀粉粒积累加剧;影响叶片中海绵组织细胞形态大小,细胞出现不正常增生,从而抑制砧?

英文摘要：

[Objective]The aim of this study was to determine the effects of boron deficiency on the cellular structures of the maturation zone in root tips and the functional leaves in citrus.[Method]A hydroponic experiment was conducted with（10 μmol·L^-1 H3BO3,＋B） and without boron（-B） treatment.Fine root mature zone and young leaf samples were observed by paraffin sections and transmission electron microscope（TEM）.[Result]Boron deficiency reduced the amount of parenchyma cell in root and,arranged loosely,led to cell deformation and enlarged the intercellular space.Also,boron deficiency caused the disintegration of the cytoplasm and organelles,and increased the cell wall.Whereas the parenchyma cell morphology was normal,evenly sized,and arranged densely in ＋B treatment,the parafin section showed the root vascular bundle was dyed deeper and the structure was clearly organized in a circular pattern around the root pulp.Low B stress seriously inhibited the development of vascular bundle and restricted its differentiation,making the cell small and randomly arranged.In the plant,Boron leakage made the leaves thick and uneven and sponge tissue became deformed,leading to bigger cell gaps and an increase in the number and volume of sponge tissue.This improved the proportion of sponge tissue in mesophyll.However,in B＋ treatment,leaf thickness was more even and the epidermis cell was more densely arranged.The palisade mesophyll was closely packed and sponge tissue underneath was loosely and organically arranged.Under B deficiency,there was also an accumulation of starch grains in the cell and leaf soluble sugar and starch content increased by 35.3% and 66.7%,respectively.But there was no obvious accumulation of starch in the leaves with ＋B treatment.[Conclusion]The internal structure of the leaf cell was destroyed by boron deficiency.Cell wall thickness and starch accumulation intensified while sponge tissue showed obvious proliferation.The leaf＇s abnormal growth further inhibited the development of leaf and