Hybridization Between Bauhinia And Identify The Genetic Relationship Of Parents Plants

Bauhinia belongs to Leguminosae, tree, shrub or climbing vine. There are about 600 species in the genera, most of them indigenous to the tropics .There are 40 species, 4 subspecies, 11 varieties in china, the main producing areas are southern and south-west.In this study, produce high ornamental value and strong cold resistance Bauhinia new varieties is the main aim, hybridization between B. galpinii and B. hupehana which growing well in non-torrid climate condition, but receive none hybridization seed, a certain reproductive isolation was inferenced by this result. So ISSR-PCR molecular marker technique was used to analyze the genetic relationship between them; and use molecular marker technique to analyze the genetic relationship between 19 Bauhinia materials which successfully introduction in shanghai, in order to provide a certain theoretical basis to hybrid breeding, direct the selection of hybridization parents.The main results of this study are as the followings:1. under 4℃and -20℃storage conditions, the downward trend about B. galpinii pollens vitality are basically identical. After stored 210 days, pollen vitality still keep on 75 percent even better than it, and pollen vitality is not the main factor restricted hybridization infertility was confirmed by hybridization experiments.2. Observations on pollen germination and pollen tubes'growth process of B. galpinii after hybridization by fluorescence microscopy. The results indicated that: pollen of B. galpinii could germinate on the stigma of B. hupehana and a little of pollen tubes can through the stigma, go on growing. But lots of abnormal phenomena were appeared, this lead to the pollen tubes stop growing while in the midway.and preliminary inference that pollen tube's abnormal behavior is the main factor restricted the inter-species incompatibility; stigma papilla cells of B. hupehana is the first barrier which have hindered the growth of pollen tubes of B. galpinii.3. High-quality DNA for PCR amplification was extracted by modified CTAB method; ISSR-PCR reaction system of total Bauhinia genus DNA was constructed, as in 10μL reaction systems, 0.25U Taq polymerase, 0.4mmol/L concentration dNTP, 0.6μmol/L concentration of each primer , 2.0mmol/L concentration Mg2+ and 20ng genomic DNA, the other composition is aseptic water which double distilled.4. Study on the genetic relationships between 19 Bauhinia materials used the 13 ISSR primers which can amplify clear banding pattern and have well polymorphic were screened from 100 ISSR primers. A total of 303 DNA bands were amplified which molecular weights between 100bp and 2000bp, of which 290 bands are polymorphic, the percentage of polymorphic bands is 95.7%. Every primer could amplify averagely 23.31 bands.5. Based on the amplified results, genetic similarity was analyzed by UPGMA and dendrogram was constructed. The results indicated that: 19 Bauhinia materials'genetic similarity is between 0.51-0.83, materials were obvious divided two groups at the genetic similarity 0.59. The first group including B. variegates etc 14 materials, and the second group including B. aurea 5 materials.6. The cluster result indicated that: B. galpinii and B. hupehana are in two large groups respectively, and the genetic similarity is 0.61, they had the relative close relationship, the inter-species hybridization may theoretically successful. So during the hybridizations after then, maintenance after hybridization should be especially paied attention to, or choose the method—Immature embryo rescue to train, with a view to receive the hybridization seeds. In addition, B. galpinii and B. khasiana had closer genetic relationship, so during the hybridizations after then, method about bridge hybridization parents should be tried, it may gain after making hybridization between them.