| Plant genetic resources are one of the most important substance bases for human to survive and develop, and to keep their diversity is the important guarantee for sustainable development. China is one of the primary origins of persimmon, and has variant genotypes of persimmon, which provide selectable breeding materials for creating better cultivars. However, planting in open field, as a traditional method for conservation of persimmon germplasm, has emerged so many faults such as diseases and insect pests, natural disasters, shortage of fund and so on, which even leads to facing loss or loss of a mass of germplasm. In vitro conservation has been becoming the key complementary conservation technique for its advantages of economy, safety and practicality'. Therefore, We have been beginning to study persimmon germplasm conservation in vitro and genetic stability of regenerated plantlets And, the major results listed as follows:1. Studies were carried out on in vitro culture of 35 genotypes of persimmon including species, cultivars and clones. The results showed that shoot tips, which were cultivated on the modified MS medium with nitrates reduced to half strength [MS(1/2N)] added with PVP 600 mg/L, sucrose 30 g/L, agar 7.0 mg/L, ZT 2.0 mg/L or CPPU 0.2 mg/L, and IAA or IBA 0~0.05 mg/L, could difference and grow better. And in vitro shoots increased by several times. The cost had been reduced greatly when CPPU was adopted instead of ZT above in vitro culture system of persimmon.2. The factors influencing rooting of persimmon shoots in vitro were studied: The results showed mat shoots subcultured constantly for certain times were dipped in IBA solution 250mg/L for 15s, and were incubated on the 1/2MS(1/2N) medium containing activated charcoal 1000mg/L, or were directly inoculated on the rooting medium above added IBA Img/L, which was better for rooting.3. Single-bud sibling lines of 7 persimmon genotypes were established, which provided materials for the studies on genetic stability of conserved regenerated plantlets.4. In vitro shoots were conserved for 4~5 years by subculture at normal temperature and genetic stability of 5 in vitro conserved genotypes was detected The results showed no changes of DNA content and chromosome number were found. And when variation at DNA level was tested by RAPD, there were no aberrant bands presenting among amplified 3648 bands of 6 clones of Jirou and 4752 bands of 8 clones of Luotiantiansbi, the aberrant frequency being 0.028% among 3624amplified bands of 6 clones of Maekawa-Jirou, the aberrant frequency being 0.031% among 3670 amplified bands of 10 clones of Matsumoto-Wase, the aberrant frequency being 0.064% among 4696 amplified bands of 8 clones of Date plum, and the aberrant frequency being 0.016% among 6380 amplified bands of 10 clones of Mopanshi. It revealed that conservation in vitro shoots of persimmon by subculture for long term resulted in variation at DNA level potentially.5. Approaches for conservation of in vitro shoots by slow growth and detecting the genetic stability of regenerated plantlets were established in persimmon. On an average, 90% among in vitro shoots conserved for 18 months at 6 and 800 be (12h photoperiod) with 3 methods by which shoots were cultured on MS(1/2N) medium supplemented with 20g/L sucrose, 7g/L agar and 500mg/L PVP added with 20.0 g/L mannitol or 1.0 mg/L PP333 or on 1/2MS(1/2N) supplemented with 20g/L sucrose, 7g/L agar and 500 mg/L PVP added with 0.2 mg/L CPPU maintained viability. And those regenerated plantlets conserved for 18 months by slow growth were analyzed on genetic stability. As a result, among 3 single-bud sibling lines of Jirou and Date plum conserved with PP333, there were no changes of DNA content and chromosome number, and 0.16% aberrant frequency existing among 1827 bands and 0.86% aberrant frequency existing among 1736 bands amplified by RAPD respectively. And no variations of regenerated plantlets conserved by another two methods were found by cytological and molecular measures.6. A p...
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