遮荫对南美蟛蜞菊、蟛蜞菊及其自然杂交种叶片显微结构及叶绿体超微结构的影响

Effects of shade on the leaf microstructure and chloroplast ultrastructure of the invasive Wedelia trilobata, the native W. chinensis and their hybrid

关键词:  蟛蜞菊属  自然杂交种  遮荫  叶片解剖结构  叶绿体超微结构

Key words:  Wedelia  natural hybrid  shading  microstructure  chloroplast ultrastructure

摘要:

利用JSM-6360LV型扫描电镜和JEM-1010型透射电镜,观察了南美蟛蜞菊、蟛蜞菊及其自然杂交种新近成熟和老熟叶片的解剖结构及叶绿体超微结构。结果表明:遮荫后该杂交种与其亲本新近成熟叶片均表现为上下表皮气孔密度、叶片总厚度及上下表皮厚度、栅栏组织、海绵组织厚度减小,叶绿体肿胀变形,基粒片层垛叠程度增加,淀粉粒增多变大; 遮荫后杂交种老熟叶片总厚度及上表皮、栅栏组织、海绵组织厚度增加,入侵种的下表皮厚度及本地种的上表皮厚度增加,叶绿体超微结构在遮荫后均出现严重损伤,基粒片层类囊体结构边缘溶解等。说明三种蟛蜞菊属物种及各物种不同叶龄叶片对弱光条件的响应存在差异; 杂交种叶片显微及超微结构在不同光照下的变化介于亲本之间,对遮荫环境能较好适应。

Abstract:

The microstructure and the chloroplast ultrastructure of the primary fully expanded mature and senescent leaves of Wedelia trilobata,W. chinensis and their hybrid under shade and full light have been investigated using scanning electron microscope(SEM,JSM-6360LV)and transmission electron microscope(TEM,JEM-1010). In contrast to full light treatment,the primary fully expanded mature leaves of the three species under shade treatment had reduced stomatal density of both upper and lower epidermises,and smaller leaf thicknesses and thicknesses of upper and lower epidermises,palisade tissue and spongy tissue. Moreover,the chloroplast of the primary fully expanded mature leaves,the stacking of grana lamellae increased and the number of the starch grain increased. However,the effects of shade on the microstructure of the senescent leaves were different to that found in primary leaves. For hybrids,the thicknesses of the upper epidermis,the palisade tissue,the spongy tissue and the whole leaves increased. Also,the thickness of the lower epidermis of the invasive species(W. trilobata)and the thickness of the upper epidermis of the native species(W. chinensis)increased. Moreover,the ultrastructure of their chloroplasts had more severe impairment under shade treatment,e.g. the grana lamellae had edge-lysis. Conclusively,the response in leaf microstructure and chloroplast ultrastructure varied among different Wedelia species and different leaf developmental stages within the same species; the hybrid showed intermediate response between its parent species.