| Excellent traits could be combined by hybridization which has played an important role in genetic improvement of plant. It is urgent to provide new cultivars with excellent trait in Chinese jujube industry. However, up to now, no cross cultivars has been successfully utilized in Chinese jujube. There are two obstacles in Chinese jujube cross, difficulty in manual emasculation and embryo abortion. Chinese jujube flower is small with diameter 3-5 mm and inevitable hurt to flower during manual emasculation usually caused failure in pollination. Simultaneously, heavy embryo abortion occurs in most Chinese jujube cultivars and hybrid seed is absent in most fruit in cross breeding. Both obstacles could be absolved by combination of the use of male sterile germplasm and immature embryo culture. The object of the study is to establish the cross technology basing male sterile germplasm and embryo culture and prepare for mass cross. The main results were as follows:1 The male sterile strait of JMS3,'Chinese jujube male sterile NO.3'was stable. Test of pollen number per anther of Chinese jujube changed during flower season from 2006 to 2007 and the highest level pollen number usually appeared at the peak of flower season. Compared to cultivars which pollen number changed, no pollen was found in yellow bud of JMS3. So, JMS3 was a material with stable male sterility.2 Plant could directly regenerate from immature Chinese jujube embryo at late development stage and Plant regeneration could also be achieved from callus induced from cotyledons in immature fruits. Callus could be induced from cotyledon of JMS3 in medium MS +suger 30g/L+agar 3.3g/L without hormones and the callus rate was 40%. Adventitious buds occurred in 88.9% of callus cultured in medium MS +suger 30g/L+ agar 3.3g/L+TDZ 1.5 mg/L. Rooting medium was MS + suger 30g/L+agar 3.3g/L + IBA1.0 mg/L and the rooting rate was 33.3%. In addition, the growth of vitrified plants was influenced by culture temperature. Only 9.7% of vitrified plants changed into normal plants after they were cultured 30 days at 24℃. In contrast, only 6.7% of plants kept vitrified 30 days later at 20℃. However, there was no obviously different changes of vitrified plants which were cultured in mediums supplemented 30-80g/L suger. 3 Embryo at late development stage from JMS1 and JMS3 in controlled crosses JMS1×'Dasuanzao'and JMS could not germinate when they were directly inoculated. In contrast, the germination rate of embryo reached as high as 75% after pretreatment under 0-4℃for 60 days. Comparison of plant regeneration from embryo at different development stage indicated that severe mature of embryo hindered its direct germination. It was related to accumulation of ABA in embryo at its late development stage.4 Hybrid from controlled cross of Chinese jujube could be identified by RAPD markers. A total of 38 band were obtained from'Lajiaozao','Zizao'and 18 offspring and the average band per primer was 5.The most bands is 7 and amplified by OPE-06. The smallest band is only 2 obtained by primer S186. Markers present only in farther parent'Lajiaozao'were amplified by primers OPG-06,OPE-06,S130 and S200.The total number of markers present only in farther parent'Lajiaozao'is 7, including S130-650,OPE-06-550, OPE-06-380, OPG-06-2000, S200-700, OPE-06-1250 and S200-490. OPE-06-1250 and S200-490 appeared in all 18 offspring and they were hybrid. Markers present only in'Wuhezao'or'Dongzao'were amplified by 4 primers. OPE-02-2100, OPE-02-500, S200-600, OPE-09-1000 and OPE-06-600 appeared only in'Wuhezao'and OPE-02-1000, OPE-02-700 and S200-500 only in'Dongzao'. Finally, 12 hybrid of'Dongzao'×'Wuhezao'and 1'Wuhezao'×'Dongzao'were obtained using these farther markers. |
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