(k) Figure 7 Process of microspore development of hybrid(1000x).(a)Abnormal developed anther chamber:(b)PMC formation stage.normal PMC and 4 layers of anther wall:(c)PMC formation stage.showing PMC degeneration:(d)PMC formation stage.showing degenerated PMCs and tapetum and middle layer:(e)prophase I.showing vacuolated cytoplasm of PMC and abnormal proliferated taperum:(f)prophase I showing de- generated PMCs and normal tapetum:(g)prophase I,showing both PMCs and tapetum degenerated:(h)early uninucleate microspore stage.showing a few degenerating microspore in an anther chamber:()middle uninucleate microspore stage.showing an abnormal huge microspore:()middle uninucleate microspore stage,showing many small granule sediments accumulated abnormally in the surface of microspore and tapetum:(k)pollen matured stage.showing remnants of abortive pollen remained in an anther chamber(x100). reproduction
Biology of plant reproduction 21
三、种间杂交杂种衰弱 Hybrid weakness 1. 定义 杂种幼苗和植株在发育期间表现： 植株矮小、长势微弱、器官畸形(organ deformation)、代谢紊乱(metabolic disturbance)→很弱甚至不能成活。 Biology of plant reproduction
Biology of plant reproduction 22 三、种间杂交杂种衰弱 Hybrid weakness 1. 定义 杂种幼苗和植株在发育期间表现： 植株矮小、长势微弱、器官畸形(organ deformation)、代谢紊乱(metabolic disturbance)→很弱甚至不能成活
三、种间杂交杂种衰弱 Hybrid weakness 1. 表现形式 ● 矮小Dwarf 圆锥烟草×郎氏烟草 ↓ F,（其高度相当于亲本的1/10) Biology of plant reproduction w
Biology of plant reproduction 23 三、种间杂交杂种衰弱 Hybrid weakness 1. 表现形式 ●矮小Dwarf 圆锥烟草×郎氏烟草 ↓ F1（其高度相当于亲本的1/10）
三、种间杂交杂种衰弱 Hybrid weakness ● 畸形(deformity):长瘤(tumour)、表皮木栓化 (corkification)、叶片卷曲(crimping)、花扭曲 (curve)、缺绿(chlorosis)等 芥菜(leaf mustard)X甘蓝型油菜(cabbage- type rape) ↓ F1(根部长瘤) Biology of plant reproduction
Biology of plant reproduction 24 三、种间杂交杂种衰弱 Hybrid weakness ●畸形(deformity)：长瘤(tumour)、表皮木栓化 (corkification)、叶片卷曲(crimping)、花扭曲 (curve)、缺绿(chlorosis)等 芥 菜 (leaf mustard)× 甘蓝型油菜 (cabbagetype rape) ↓ F1（根部长瘤）
四、杂种不育(hybrid sterility) l.定义definition 杂种植株正常但性器官或配子或配 子体不正常，无法繁衍后代。 Biology of plant reproduction
Biology of plant reproduction 25 四、 杂种不育（hybrid sterility） 1. 定义definition 杂种植株正常但性器官或配子或配 子体不正常，无法繁衍后代