| Eggplant (Solarium melongena L.) is a kind of popular vegetable with abundant nutrition, special flavor as well as peculiar medical value. In recent years, with the increase of eggplant consumption and the enlargement of its area of protected cultivation, the demand of the special variety for protected cultivation is increasing. But nowadays the varieties of eggplant for this purpose can't tolerate cold and low-light stress very well, so it is quite necessary to cultivate this kind of varieties.Since the hybrid varieties of eggplant are popularized continuously, many regional varieties have been lost and eggplant's genetic background has been narrowed. So far, as the cold-tolerant materials haven't been found in cultivars, it is very difficult to obtain cold-tolerant varieties by conventional means. Through gene transferring and somatic hybridization, cold-tolerant varieties have been obtained and the exploitation of somaclonal variation of some crops also succeeds. The variation is quite common among regenerated plants after tissue culture, and the frequency of mutation is very high. It can occur both at chromosomal and molecular levels. And many disease-resistant and adversity-tolerant varieties have been developed through in vitro selection with stress.With the condition of our laboratory, the in vitro culturing procedure of eggplant had been well established and through in vitro selection cold-tolerant calli and their regenerated plants had been obtained in the research. The main results were as follows:1. Calli from hypocotyl and cotyledon explants of eggplant were obtained on MS culture medium supplemented with NAA and BA of different concentrations, but there was distinctive difference among genotypes. The combination of BA and NAA had great influence on callus induction of eggplant. One of these combinations, 2.0 mg/L BA and 0.2 mg/L NAA, induced a type of compact callus in color varied from light yellow to light green, which was beneficial to differentiate into adventitious buds.2. Calli of all eggplant genotypes were able to differentiate into adventitious buds, but their differentiation rates were significantly different. Although the optimum growth regulator combination for differentiation from calli to adventitious buds depended on genotype, BA with a concentration ranging from 2.0 mg/L to 4.0 mg/L played an important role in the process and AgNO3 played an auxiliary role.3. Roots could form on 1/2 strength MS culture medium containing 0.2 mg/L NAA or not. After 2~3 weeks, regenerated plants were carefully transplanted to flowerpots individually, then cultured under the condition of 28 C or so and high humidity, finally they grew very well.4. After subculture calli were transferred to subculture medium containing L-hydroxyproline(L-Hyp) with different concentration. With the increasing of its concentration, the survival rate of calli decreased gradually. When the concentration was 8 mmol/L, the survival rate of calli was only 4. 3%. And when increased further the concentration, calli couldn' t grow. Therefore, it was promising to obtain Hydroxyproline-resistant mutants with 8mmol/L L-Hyp as selection stress.5. After repetitive selection with 8 mmol/L Hyp as selection stress, hydroxyproline-resistant calli were obtained, then differentiated into plants. The hydroxyproline-resistant calli had significant higher proline content and higher soluble sugars, while significant lower malondialdehyde content and lower electrical conductivity compared wth controls when identified with physiological and biochemical indices of cold-tolerance of eggplant. So they showed a significant better cold tolerance than controls. The regenerated plants had significant higher proline content and significant lower electrical conductivity than controls. They exhibited stronger cold tolerance than controls.
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