In Vivo Polyploid Induction Via Callus In Chinese Jujube And Sour Jujube

Chinese jujube is a kind of special fruit tree derived from China. Because of thedifficult of the traditional cross breeding, polyploid breeding is paid much more attention.In this study, we established no mixploid polyploid induction system, determinationsystem through in vivo treatment to callus with colchicine. What’s more, the originationof regenerated bud was also studied. The results were shown as follows:1. Through treatment with growth regulator to girdling wound, callus could be easilyget but difficult to regenerate new bud from callus. At the4thto5thday after callusinduction, a little callus could be seen. At the40thday, no bud regenerated from callusand the inner callus had been lignification.2. The influencing factors to buds regeneration system from callus of young branches(1-3years old) cross section were studied, including genotypes, branch age and diameter,cutting time and the concentration of TDZ. Genotype plays a bigger role for budregeneration. Chinese jujube ‘Yueguang’,‘Dalilongzao’ and sour jujube ‘Xingtai0605’were easy to regenerate new buds from in vivo callus. A few adventitious buds could beobserved at the15thday after branches being cut and induction. At the20thday, theaverage buds number in average branch cross section could reach to6.92in ‘Yueguang’.However,‘Dongzao’,‘Zanhuangdazao’ and ‘Suanzao C16’ were difficult to regeneratenew bud. No bud regenerate at the15thday after branches being cut and induced, andonly0.11per cross section another5days later. For ‘Dalilongzao’ which is easy toregenerate new buds, both callus and adventitious buds could be obtained easily. Theaverage number per branch cross section could reach to4.78. The more suitable branchdiameter is15-25mm. For branches with equal diameter, adventitious buds could beobtained more easily from new shoots. For genotypes which are difficult to regeneratenew buds, a higher TDZ concentration treatment could enhance the number ofregeneration buds, but could not make it early to regenerate. The better TDZconcentration is8mg/L and12mg/L, in which the regeneration adventitious budsnumber could reach to0.75.3. The influence factors to polyploid induction effect to callus in branches crosssection were studied, including branch ages, genotypes, dosage of colchicine and treatment time. Results showed that both callus and new buds could be more easilyobtained from cross section of young branches (1-3years old) than old branches (morethan3years old).20Chinese jujube genotypes and37sour jujube genotypes werestudied for polyploid induction.11Chinese genotypes and24sour jujube genotypes wereregenerate adventitious buds successfully. At last, pure polyploid of4Chinese jujubegenotypes(‘Dalilongzao’,‘Jinsixiaozao’,‘Wuhe68’,‘Maoboyanliangzao’) and9sourjujube genotypes(‘Xingtai0604’,‘Xingtai0605’,‘Xingtai0608’,‘Xingtai0610’,‘Xingtai0618’,‘Xingtai0641’,‘Beiqi11’,‘Ziayuanpu8’,‘Suanzao17’) were obtained.The more suitable treatment is0.05%colchicine at the third day for1time.5purepolyploid new buds could be gained from12branches treatment and two of thembloomed in the experimental year.4. As can be seen from different steps of new adventitious buds, variation new budswere thicker than diploid ones. In the young shoot step, it can be seen that tetraploidshoots were still thicker and stronger than diploid, octaploid shoots grew very slowly andmixploid shoot became curl. Flatten young leaves of tetraploid is border than diploid, butoctaploid leaves became smaller than both diploid and tetraploid. Mature leaves almosthave the same shape character with flatten leaves. Compared with FCM detection, theaccuracy of flatten young leaves detection had no significant differentiation. That is tosay, the ploidy of new shoots could be detected accurately through flatten young leaveshape. What more, both tetraploid and octaploid buds could be gained via colchicinetreatment to in vivo callus.5. The character of different ploidy materials were studied systematically. The leavesof tetraploid were border than diploid. However, the leaves of octaploid became smaller.As ploidy increased, stomata became bigger and their density decreased(the ratio oflength of stomata:4x/2x≈1.5，8x/4x≈1.4，8x/2x≈2). The pollen diameter of tetraploid isalso bigger than diploid significantly(4x/2x≈1.3).6. Through observation with naked eye, anatomical lens and microscope, the originof new buds was studied systematically. There are mainly two approaches in the in vivocallus bud regeneration system, the one is somatic embryogenesis, and the other isadventitious buds regeneration. Somatic embryogenesis was very rarely, which is onlyobserved in sour jujube experiment. Through observation with microscope, we found thatcell of cambium divided into cell mass firstly. Then some of cells in the cell massdifferentiated into buds primordium, which combined with stock plant gradually throughvascular bundle. The development of all adventitious buds was not consistent. We canensure that adventitious buds derived from new informed callus, and infer thatadventitious buds derived form one or a few cells. With the colchicine treatment timedelayed, the ratio of mixploid increased. The mixploid percentage could reach to17.65%at the tenth day treatment. These mixploid may derived from incomplete chromosome number doubled multiple cells. The ratio of tetraploid could reach to23.53, which mayderive from single cell.7. The in vivo callus buds regeneration and polyploid induction system was also triedin elm, Malus spectabilis, mulberry and acer monoes. Callus was gained from branchcross section in elm, Malus spectabilis and acer monoes successfully. What’s more,adventitious buds regenerated and polyploidy buds were also obtained from callus of elmsuccessfully.