Demonstration and induction of apomixis in the genus Diospyros and its utilization for polyploidy breeding

1. 为了证实无融合现象的发生，我们以Diospyros lotus和d.f iriniana为种子亲本，进行了种内和种间传粉。一株荷花不仅通过种内传粉，而且通过种间传粉实现了坐果和种子形成。从这些种子衍生的种子的DNA条带分析（RAPD和AFLP）来看，种间传粉衍生的种子显示出与种子亲本相同的条带，但没有显示出与花粉亲本相同的条带，表明种子形成是无融合的。另一方面，树内传粉的幼苗大多表现出与花粉亲本相同的条带模式，但也有一些表现出无融合的种子形成。D. virginia未出现无融合现象。形态学观察表明，大部分胚发生正常，但也有减数分裂在二分体阶段失败，一个二分体退化，另一个正常胚发生。这表明本种的无融合性为双孢子型，在菊科中可见。用γ射线照射后的红木花粉授粉，未诱导无杂交种子形成。为了寻找无融合性自然发生的可能性，利用倍性分析仪对10个品种的多株油菜幼苗进行了倍性测定。多倍体变异频率高，如非单倍体、十二倍体及其非整倍体和六倍体。Fujiwaragosho。需要揭示它们是否来源于无融合。这些多倍体可作为未来木薯选育的新种质。

1. To demonstrate the occurrence of apomixis, intra- and interspecific (D.kaki) pollinations were conducted using Diospyros lotus and D. virginiana as seed parents. One strain of D. lotus showed fruit setting and seed formation by not only intra- but interspecific pollination. In the banding pattern of DNA anlyses (RAPD and AFLP) of the seedlings derived from these seeds, those derived from interspesific pollination showed the same banding pattern as seed parent, but did not show that as pollen parent, suggesting apomictic seed formation. On the other hand, the seedlings from inraspecific pollination mostly showed the same banding pattern as that specific to pollen parent but some showed apomictic seed formation. D. virginiana did not manifest apomixis.2. Morphological observation of D. lotus showed that most embryogensis normally proceeded but in some cases meiosis failed at a dyad stage, one of the resultant dyads degenerated while the other proceeded normal embryogenesis. This suggests that the apomixis in this species is diplospory type as seen in Compositae family.3. Pollination with γ-ray irradiated pollen of D. kaki did not induce apomictic seed formation in this species. To search for the possibility of natural occurrence of apomixis in D. kaki, ploidy determination of many seedlings derived from 10 cultivars was conducted by using a ploidy analyzer. High frequency of polyploid variation, such as nonaploid, dodecaploid and their aneuploids as well as hexaploid, was specifically found in cv. Fujiwaragosho. It was needed to reveal whether or not they derived from apomixis. However, such polyploids could be used as novel germplasms for breeding of D. kaki in the future.