桃蚜诱导杏幼叶局部细胞超微结构退化

Ultrastructural degeneration of part cells in young leaves of apricot caused by green peach aphids

蚜虫是以植物韧皮部汁液为食的专性寄生昆虫,杏树春生新梢易受桃蚜等蚜虫侵染,桃蚜在新梢上迅速繁殖并聚集,汲取韧皮部富含糖分的汁液,通常引起杏叶卷曲变形,抑制新梢生长。为了解桃蚜侵染对杏幼叶超微结构产生的影响,以采集被蚜虫寄生的幼叶,经过固定、脱水和包埋,做成厚度60 nm超薄切片,采用透射电子显微镜进行观察。结果表明,受桃蚜侵染幼叶中有少数细胞表现超微结构变化:细胞过度液泡化以致液泡占据了细胞绝大部分内部空间,同时,细胞质过度降解,细胞器减少,细胞核收缩,核质中均匀地积累嗜锇性细颗粒物质致使细胞核电子染色加深,染色质颗粒消失,细胞壁增生导致细胞变形。根据观察结果得出结论,桃蚜侵染杏幼叶能引起幼叶局部细胞发生超微结构退化。

Aphids are plant phloem-feeding insect, sucking the sugary liquids from the host plant＇s vascular system. Green peach aphids （Myzus persicae ） often infest the emerging shoots of apricot （Prunus armeniaca Linn.）. The aphids reproduce rapidly and cause severe distortion of young leaves and inhibit the growth of the new shoots. In order to characterize the ultrastrueture alterations in the infested young leaves, leaf samples were examined by means of transmission electron microscopy. Most cells in the in- fested young leaves were moderately vaeuolated and appeared healthy, but there were a small number of cells that showed excessive vacuolation and cytoplasmic reduction. In the excessively vacuolated cell, a large vacuole occupied almost all the cell＇s total volume, whereas cytoplasm was reduced to very little. The excessive cytoplasmic reduction was concomitant with nucleus deterioration. The nucleus deterioration was symptomized as nucleus shrinkage, extensive accumulation of diffusible osmiophilic compounds, and disappearance of chromatin granules. The excessive cytoplasmic reduction and the concomitant nucleus deterioration led to the subsequent cell distortion. Results suggested that the infestation of green peach aphids caused uhrastructural degeneration to a limited number of cells in the infested young leaves of apri- cot.