摘要
集应用免疫细胞化学及显微红外光谱分析技术，深入研究了硼元素对花粉管生长的调节作用。用识别甲酯化果胶的单克隆抗体JIM7和识别酸性果胶的JIM5对离体培养的百合（LiliumlongiflorumThunb．）及烟草（NicotianatabacumL.cv．“PetitHavana”）花粉管进行免疫荧光标记，发现无硼培养导致细胞壁果胶成分呈异常分布，酸性果胶在花粉管顶端大量富集；苯胺蓝诱导荧光法揭示，无硼培养引起胼胝质在顶端细胞壁积累。通过显微红外光谱（FTIR）分析，进一步验证了无硼培养导致细胞壁酸性果胶质含量的增加，并发现酚酯含量比正常情况减少，而游离酚类化合物含量明显增加。上述结果表明，硼可能作为一种相关因子影响关键酶活性，改变细胞壁多糖网状结构以至细胞壁的延展性，从而调节花粉管生长；酚类积累对质膜完整性的影响也会对调节花粉管生长有间接作用。
In an attempt to understand the functions of boron in the regulation of Pollen tube growth, thestructure and localizat ions of two major polysaccharide components, pectins and callose, in cell walls were studied in pollen tubes cultured in standard medium and boron-deficient medium, respectively.Immunochemical localization of acid pectin and methyl-esterified pectin in the walls of pollen tubes of tobacco (Nicotiana tabacum L. cv. 'Petit Havana' ) and lily (Lilium longiflorum Thunb. ) was investigated by using monoclonal antibody JIM7 and JIM5 and observed by means of confocal laser scanning microscopy (CLSM).Most of the boron-deficient pollen tubes were remarkably labelled by JIM5 in the wall of tip region,demonstrating an abnormal accumulation of acid pectin in the pollen tube tip, which is the only growth region of the cell. The localization of (1-3)-β-D-glucan (callose) in the walls of pollen tubes was revealed by ultraviolet excitation of aniline blue staining. The accumulation of callose was also found in the wall of the tipregion of the pollen tubes cultured in the boron-deficient medium. In addition, the changes in the structures of pectins and phenols were investigated by fourier transform infared (FTIR) microspectroscopy. It was further confirmed that boron deficiency caused the increment of acid pectin in the pollen tube walls. The increase in the content of phenolics and the decrease in that of phenolic esters were also revealed in boron-deficient pollen tubes. These results imply that boron may function as a regulatory factor of pollen tube growth by affecting the activity of the corresponding enzymes that induce the changes of polysaccharide network and thus the extensibility of the cell wall. The accumulation of free phenolic compounds influences the integrity of plasma membrane, which might also contribute to the regulation of pollen tube growth.
基金
国家自然科学基金!39770081
