以同一稻穗内的不同部位小穗轴为材料,利用低温包埋、免疫胶体金标记和透射电镜技术,对维管束韧皮部的超微结构差异及其花后动态变化进行观察比较,并对筛管-伴胞细胞中的CaM活性与分布进行细胞化学定位.结果表明,稻穗不同部位小穗轴的维管束组织结构差异,主要表现在中央大维管束的总面积、韧皮部面积和导管面积上,强势粒小穗轴的维管输导组织结构一般优于弱势粒小穗轴;水稻抽穗开花后不同部位小穗轴中央维管束筛管分子和伴胞等细胞的超微结构变化过程大致相同.其中,筛管分子在水稻开花前均已分化成熟,而伴细胞仍保持着较完整的细胞结构特征,之后逐渐呈现出明显的退化迹象:与弱势粒小穗轴相比,强势粒小穗轴在灌浆启动时筛管厚壁和伴细胞中的线粒体等细胞器和胞间连丝的数量丰富、CaM标记密度高,表现出较明显的启动机能和输导生理优势,但至水稻灌浆中期之后,不同粒位间小穗轴的输导生理差异可能并不明显.%The ultra-structure of the vascular bundle phloem in rice rachilla and its time-course during grain filling period were observed for different positional rachillae within a rice panicle by using low-temperature embedding and electron microscopy technique, and CaM distribution in sieve element (SE) and companion cells (CC) of the central vascular phloem was investigated by immuno-gold localization. The results showed that there were obvious difference in the anatomical structure of the vascular bundle between different positional rice rachillae, with the relative large total vascular area, phloem area and vessel area in central vascular bundle for superior positional rachilla within a panicle, indicting that the superior rachilla had better structure for the assimilate transport compared to the inferior positional rachilla; the similar time-course in the degradation pattern of some orga-nelles of SE and CC in central vascular phloem was observed in different positional rachillae at grain filling stage, with the relative delaying degradation and disintegration of SE, CC and phloem parenchyma cells for inferior positional rachilla; the abundant mitochondrion, chloroplast, starch granules and plasmodesmata, and numerous CaM labeling density were found in SE and CC of superior rachilla compared to inferior positional rachilla at beginning filling stage, while no significant differences between two types of rachilla at middle and late filling stages, implying that superior postional rachilla had relatively better transporting function at initial filling stage relative to inferior rachilla.
展开▼
