干旱胁迫对玉米花粉和花丝表面超微结构及两者活力的影响

Effects of Drought Stress on Surface Ultrastructure and Vigour of Pollen and Filament

电子显微镜下观察发现:干旱胁迫对玉米花粉和花丝表面超微结构均产生了明显的影响。随着干旱胁迫强度的加重,玉米花粉外壳出现逐渐加宽加长的网纹状突起,内壳出现不均匀泡状突起,最终形成网纹状泡状突起;同时,花丝表面横向收缩、高低不平,部分薄壁细胞互相挤压离位,出现塌陷,薄壁细胞横向排列拥挤,花丝表面形成明显的"垄"形结构,绝大多数薄壁细胞表面形成凹陷,花丝毛明显减少,几乎所有剩余的花丝毛均倒伏于花丝表面上。干旱胁迫条件下,花粉和花丝表面超微结构的变化对花粉管进入花丝维管束鞘细胞造成障碍,加之干旱胁迫条件下,花粉和花丝SOD活性降低,自由基清除能力下降,膜脂过氧化作用的终产物MDA含量剧增,生物膜受到直接伤害,结果造成有效花粉数目减少,花粉和花丝活力下降,授粉、受精不良,出现大量不育粒,有效粒数减少,粒重下降,最终导致产量降低。

It was observed and discovered under electronic microscope that the effects of drought stress on surface ultrastructure of pollen and filament were quite obvious. With the deepening of drought stress, the net vein protuberance on exterior shell of maize pollen appeared and became gradually wider and longer. Inner shell appeared asymmetry protuberance like vesicle and finally formed net vein protuberance like vesicle. At the same time, the filament surface shrank horizontally and unevenly. Part parenchyma cell extruded each other and left original location, and appeared dent. The special structure like ridge in a field formed. Many parenchyma cell surface sunk and filament hair significantly reduced. Almost all residual filament hair lodged on the surface of filament hair. The changing of surface ultrastructure of pollen and filament prevented the pollen tube from entering the vascular sheath cell of filament under drought stress, and additionally, SOD activity pollen and filament decreased and membrane lipid perioxidation enhanced, which led to direct injury on the biological membrane system and a sharp increase of electrolyte leakage in maize pollen and filament tissue. These ultrastructure changes led to disorders in metabolism, hindered the development of pollen and filament, decreased pollen and filament fertility, and finally resulted in a reduction of grain number and grain weight per ear.