Abstract: This study aimed to reveal the changes in cell and tissue structure of leaves and stems of alfalfa (Medicago sativa L.) after being damaged by thrips and its correlation with alfalfa tolerance to thrips. Thrips-resistant alfalfa clone R-1 and thrips-susceptible alfalfa clone I-1 were selected as materials to compare the changes of leaf and stem microstructure and leaf ultrastructure after damaged by thrips. The results showed that the tissue structure of R-1 and I-1 alfalfa changed obviously after being injured by thrips:the serrated edge of cells were disappeared,the cells were uplifted significantly and the stomata were shrunk,the number of cells and stomata per unit area increased significantly in the upper and lower epidermis of alfalfa leaf. The distance and diameter of the vascular bundle became smaller,the number of the vascular bundle cells decreased,and the width of collenchyma decreased,the epidermal cells became shorter and narrower,the number of cells and stomata increased obviously in the stem of alfalfa. The cells were contracted,vacuoles became smaller,chloroplast starch granules became smaller or decreased,the grana of chloroplast lamellae and osmiophiles increased in palisade tissue of alfalfa leaf. The number of cells and stomata per unit area of the upper and lower epidermis of R-1 leaves healthy were less than those of I-1. The number of cells per unit area in the upper and lower epidermis of R-1 leaves damaged increased by 1.75 and 1.51 times,respectively,and the number of cells increased,chloroplast lamellae and grana were more than those of I-1 leaves damaged. In conclusion,the change of R-1 tissue structure was more significant than that of I-1 after being damaged by thrips.

Key words: Alfalfa, Thrips, Microscopic structure, Resistance to insect

摘要： 为了揭示蓟马为害后紫花苜蓿（Medicago sativa L.）叶片和茎秆细胞组织结构的变化及其与苜蓿耐害性的关系，本研究选用抗、感蓟马苜蓿无性系R-1和I-1，比较蓟马为害后苜蓿叶片和茎秆的显微结构及叶片超微结构的变化。结果表明，受害后，R-1和I-1苜蓿的组织结构有明显改变：叶片上下表皮细胞锯齿边缘消失，细胞显著隆起，气孔缩小，单位面积细胞和气孔数显著增加。在茎秆中，维管束间距和直径变小，维管束细胞减少，厚角组织宽度下降；表皮细胞变短变窄，细胞和气孔数明显增加。叶片栅栏组织细胞收缩，液泡变小，叶绿体淀粉粒变小或减少，叶绿体片层基粒增加，嗜锇体增多。健康R-1叶片上下表皮单位面积细胞和气孔数均少于I-1。受害后，R-1叶片上下表皮单位面积细胞数分别增加1.75和1.51倍，细胞增加倍数、叶绿体片层和基粒均多于I-1。受蓟马为害后，R-1组织结构的变化较I-1更显著。

关键词: 苜蓿, 蓟马, 显微结构, 抗虫性