| Fruit natural mutant (sport) is helpful to enrich wild germ plasm resource and provide precious material both for new cultivars and the study of special gene site. Kiwifruits with dark-red flesh are rare and not reported at home and abroad; The shelf life of early-ripening honey peach being rather short, it is valuable to select new cultivars (line) with different ripening date. Red Sun Kiwifruit and its dark-red-fleshed sport (86-3) as well as Zao Xia Lu Peach and its late-riping sport (Pv) were studied on fruit quality, pollen morphology, POD and EST isoenzyme electrophoresis and RAPD.A series of technology for forecasting sport seedlings of both materials had been set up. The main results were showed as follows:1. The anthocyanin content of flesh in 86-3 was significantly higher than in its maternal cultivar. The flesh of both inner and outer layer was red and the mutant character was stable. The fruit characters of 86-3 were good except for its lighter fruit weight .So 86-3 is an excellent bud mutation. The ripening date of Pv was 7~8 days later than Zao Xia Lu and its fruit quality was much better. Both of the bud sport materials were promising in the market2. The pollens of 86-3 and CK were tricolpate small ones with their diameterlO~25 m. But there were some differences in the size, shape, P/E and exine ornament between them. Pollen morphology is mainly controlled by its genes and slightly affected by the environmental factors. The differences of pollen morphology between 86-3 and CK showed the genetic substance had changed.3. The result from leaves isoenzyme electrophoresis was the following. There were 4 more bands of POD isoenzyme in 86-3 than in CK, whose Rf values were 0.38,0.42,0.48 and 0.67 respectively, while the band of Rf0.09 had stronger activity in CK than in 86-3. As to EST isoenzyme, there appeared 2 new bands (Rf0.52, Rf0.55) and enhancement of enzyme activity of 4 other bands in 86-3.compared with Zao Xia Lu, in the isoenzyme pattern of its sport band Rf0.43 was absent, a newband Rf0.26 appeared and the activities of other isoenzymes decreased. While there was little difference between their POD isoenzyme profiles.Enzyme is the expression product of gene. The differences of isoenzymes from the mutative materials reflected the changes in gene constitution or expression of the isoenzyme tested. For this study, POD, EST are available to kiwifruit analysis, while only EST could be applied to peach.4. Genomic DNAs from Red Sun Kiwifruit and its sport 86-3 were amplified by RAPD with 300 10-bp random primers. Among the primers most amplification products were monomorphic, only 10 of which could generate polymorphic fragments. 20 out of the 148 amplified fragments were distinctive including presence and absence of segments. The differences of amplified DNA fragments showed that the mutation of flesh color was related to changes of some genetic substances. Genomic DNAs from CK and single grafted trees of 86-3 scion with different tree age or rootstock were randomly amplified respectively by Primer S107 % S84 % S157and AY17. The result that each grafted tree has the same polymorphic fragments as 86-3 predicted flesh of the grafted tree would be dark red like 86-3.the inference had been proved true by the ripe fruits later on. The specific fragment could be used to forecast the flesh color of young grafted plants from the sport scion.More than 300 single and 108 mixed random primers were used to amplify the genomes from Zao Xia Lu Peach and its sport. As a result, the profiles amplified by RAPD in both materials were almost identical except one fragment intensity differences amplified by primer S46S. The result showed that these primers hardly combined with the changed sites of genomic DNA. Perhaps the sport material was point mutation. Further research about mutant site needs to be carried on. |
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