| Strawberry (Fragaria ananassa. Duch) is a kind of renascent species classified to Rosaceae, Fragaria. With attractive colorful fruit, special flavor and rich nutriment, strawberry has being developed rapidly in our country and production area is getting larger and larger. Traditionally, strawberries are vegetative propagated from runners that are often infected by a number of aphid-born viruses in the perennial cultivation period. The loss of yield in strawberry due to virus-disease is estimated to be 30-80 percent per year. As we know there is little effect on controlling virus-disease by chemicals so using virus-free stocks is an efficient way to inhibit the epeidemics of the disease. Strawberry anther culture is an important method to obtain virus-free stocks, however, a problem encountered is that the plantlets from anther culture are not haploid but diploid. In previous studies the cytological origin of ploidy unreduced regenerate plantlets from anther culture is putative either from somatic cells, unreduced microspores or be the result of spontaneous chromosome doubling. The cytological origin of plant regeneration is therefore a main factor of influencing anther culture to adopt in obtaining virus-free stocks commercially. The present research established a techniqal system of strawberry anther culture to look insight the ploidy variation and the cytological origin of the regenerated plants with purpose of providing both theoretic and technical bases for appraising virus-free stocks obtained by anther culture. The main results obtained are as follows:1. The callus inducting rate was increased significantly and the quality of the callus was the best when the anthers at the uninucleate stage were pretreated in 4℃ for 3 days.2. Sucrose concentration and the hormone ratio of the medium had significant effects on strawberry anther culture. Results showed that 3% sucrose not only promoted callus induction but also benefited to adventitious shoots differation. In callus induction, BA and KT combination could increase the inducting rate of callus and BA combined with ZT was favor for the shoot differation. In the present research,MS+BA0.5mg/L+KT0.1mg/L+NAA2.0mg/L was proved to be more optimal in callus induction and MS+BA2.0mg/L+ZT2.0mg/L+NAA2.0mg/L was promising to adventitiou shoots differation respectively.3. Inoculating temperature of 20℃ was piror to 25℃ to obtain more vigorous callus as well as to improve the subsequent shoot regeneration.4. From October to the next March in Wuhan, strawberry has 3 anthotaxy normally. The results indicated that the first anthotaxy is more suitable for anther culture than of the second or the third in callus induction.5. Among the 43 anther derived lines investigated, 39 were octoploid (2n=8x=56), 4 hexadecaploid (2n=16x=112), and no haploid (2n=4x=28) was observed.6. The uninucleate pollen could start devision in the early inoculate time, but only after several divisions, the microspore disintegrated, and thus, there were no callus originated from pollens. All plantlets from anther culture in the present research were proved to originate from somatic cells.7. Field trial showed that plantlets obtained from the anther culture had excellent growth vigor and potential productivity with improvement in yield and quality but without morphological variation compared to the wild types. |
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