杂交粳稻F2代一粒双苗的倍性鉴定

从杂交粳稻3优18等8个组合的F2代中筛选一粒双苗,并对存活的双苗进行根尖染色体数目和花粉育性的观察鉴定。结果表明：在127610粒3优18F2种子中筛选到双苗16株,双苗率为0．0125％。获得的一粒双苗分为Z-A型和Z-a型两类,每苗都有独立的根系。Z-A型双苗中,Z苗和A苗的根尖染色体数目都是24;Z-a型双苗中,Z苗的根尖染色体数目是24,a苗的根尖染色体数目为12。Z-A型双苗中,Z苗和A苗植株的花药内充满了花粉粒,Z苗植株花粉完全可育,结实正常,A苗植株花粉50％可育,50％不育,与F1相同,结实正常;Z-a型双苗中,Z苗植株花药花粉和Z-A型的Z苗一样,a苗植株花药瘦小,没有花粉粒,自交不结实。

Ploidy identification of two-seedlings per seed in F2 generation of japonica hybrid rice ( Oryza sativa L. )

Two-seedlings per seed were screened from F_2 generation of 8 combinations,mainly 3 You18,and root tip chromosome number and pollen fertility were observed using the two-seedlings obtained,in japonica hybrid rice.The results indicated that in 127 610 grains of F_2 seed of 3 You18,sixteen grains showed two-seedlings per seed(TSPS),frequency of TSPS being(0.012 5%.)The TSPS obtained were divided into 2 types,Z-A and Z-a.Each seedling of TSPS had independent root system.In Z-A type,chromosome number of root tip from both Z seeding and A seeding was 24,while in Z-a type,chromosome number of root tip from Z seeding was 24,and chromosome number of root tip from"a"seeding was 12.Anthers from Z plant and A plant in Z-A type were filled with pollens.In Z plant,pollens were 100% fertile and seed setting was normal,in A plant,50% pollens were fertile,another 50% pollens were sterile but seed setting was normal,the same as F_1 plants.In Z-a type,anthers and pollens from Z plant were the same as Z plant in Z-A type,anthers from"a"plant were smaller and thinner than those from Z plant,and had no pollen,no seed was set by selfing.