小麦种子成熟过程中果皮衰亡的细胞形态学研究

Cell Morphological Studies on the Pericarp Degeneration in the Mature Process of Wheat Caryopsis

为探明小麦颖果成熟过程中果皮的结构特征和细胞形态变化,以扬麦16颖果为材料,采用半薄切片对花后不同天数果皮的细胞形态进行了显微观察分析。结果表明:花后5d果皮细胞形状规则,排列有序,细胞间隙小;细胞核完整、内含物丰富,淀粉体边缘结构完好,果皮发育完成。随着颖果的成熟,果皮逐渐衰亡,组成结构和细胞形态发生了明显改变,至花后25d外果皮细胞壁明显增厚,中果皮基本消失,内果皮也较明显退化。果皮中的淀粉体有单粒和复粒淀粉体2种,淀粉粒呈圆球状或不规则形状。颖果背部和腹部果皮在早期都有淀粉体积累,后期随着果皮衰亡逐渐降解消失;发育和积累模式均与胚乳细胞中的淀粉体有显著区别。

In order to clarify developmental characteristics and the cell morphological changes of wheat pericarp during the process of maturity,caryopses of Yangmai 16 at different days after anthesis were used as experimental materials and their semi-thin sections were observed with light microscopy in this paper. The results indicated. The pericarp had developed well at 5 days after anthensis, and the shape of cells were also inerratic,arranged closely with small intercellular space,intact nucleus and rich cellular contents.Mean while, the margins of amyloplasts which accumulated in the parenchyma cells were visible.With the ripening of the caryopsis, the pericarp degenerated gradually and composition structure together with the cell form has certainly changed.The cell wall of the pericarp epidermis thickened obviously, and the mesocarp disappeared followed by the degeneration of the endocarp. Pericarp cells contained two types of starch granules： single-granule starch granules and compound-granule starch granules, and the starch granules were spherical or irregular.During the early development stage, starch granules accumulated both in the abdominal and dorsal pericarp of the cariopsis, but were gradually disintegrated and disappeared at last along with degeneration of pericarp cells.It was indicated that the development and accumulation mode of amyloplast in the pericarp were remarkable different from which in the endosperm cells.