| The aim of this study is to establish efficient apple polyploid breeding system and speed up apple breeding career that would work out for the existing problems of apple production in our country. The existing problems are mainly as follows: variety of main apple cultivar fewness, independent intellectual property rights species shot, genetic factor straitness and the progress of breeding tardiness , and so on. In order to exploit and utilize triploid cultivars, its biological characteristics had been investigated. The general idea included four steps. The first step is to select the best diploid cultivars as the excellence resource. The second step is to double it and make become tetraploid. Then the tetraploid across with different ploidy apple cultivars and obtain F1 hybrids. The last step is to determine the ploidy of hybrids by flow cytometry and AS-PCR. According to S-gen type , selecting young seedling and apple triploid cultivar breeding system.1,Experiments were carried out with new leaves of tissue culture plant of middle maturity cultivar Red General Apple (Malus domestica) to study the rate of adventitious bud regeneration. Regeneration rate have been studied by various plant growth regulator categories, concentration, darkness treatment time, and leaves part. The adventitious shoot were reproduced 3~4 generations in vitro , 3~4 top tender leaves of adventitious shoots were used as explant when the last subculture generation 25~35 days later . To cut the leaf edge off and press obverse leaf surface contact inducing medium. After 15 day darkness treatment, all treatment culture medium were moved to have light culture room, The adventitious bud regeneration rate were 100%. The optimal medium for regeneration is MS+TDZ1.0mg/L+IAA0.75 mg/L+Sucrose 30g/L , pH 5.8. The tetraploid plant were induced after the leaves were treated with the colchicine dipping for 48h, the percentages of tetraploid were 0.6%,with colchicine 40mg/L and 50mg/L on mix medium treatment the percentages of tretaploid is 0.26% and 0.37%,respectively.2,Although M.hupehensis ( Pamp. ) Rehd.var.pinyyiensis.Jiang has apomixi procreate ability, it still has hybrids. Our results showed that the rate of hybrid was 4.7 percent. The apospory may meiosis to become bivalence or trivalence, then by hybridize with foreign pollen to produce triploid or tetraploid hybrids. And these hybrids could keep the characteristic of apomixi of which was the result of whole hereditary of female unreduced gamete. But the diploid hybrids has not apomixi procreate ability. The result of paraffin slice up showed that the ovule of M. var.pinyyiensis.Jiang has MMC, we also found two-nucleus megaspore, four-nucleus megaspore and eight-nucleus megaspore. But the growth of megaspore lagged the florescence. And the flower has not pollen. Because the developing period of unreduced gamete lagged bloom, some unreduced gamete that hadn't been pollination developped apomixi procreated triploid seed, about 2.5 percent F1 hybrids which had been pollinated developped tetraploid offspring. therefore,we may hybridize different apple resource purposively and get the innovation of rootstock resource by selectting and mensurating the apomixi procreate ability of tetraploid offspring.3,To investigate the cross-compatibility in different ploidy apple cultivars, the ploidy of F1 hybrids had been detected by flow cytometry . The result showed that over 50 percent F1 offspring is diploid. And many of polyploid plant is unstable which would become diploid in growing process. The state of diploid is the most stable ploidy in apple species. We studied the ploidy of hybrids of Tetraploid Tianxing and Tetraploid Royal Gala , the result showed that the ratio of diploid and tetraploid is 18 percent, the rest being triploid. The hybrid of diploid and diploid can form a little triploid , the percentation was about 2.5 percent, but triploid percentation is lower than 0.25%. When triploid crossed with triploid , the fruit could been formed, but the seed often cease growth easily. Nevertheless, when crossed with diploid, the seed set was higher, and the average of seed is 2.5 per fruit.Many of triploid apple cultivars, such as Jonagold, Hokato, Mustu and Hac9 etc, derived from female unreduced gamete. Two S-gene of triploid hybrids obtained from Tianxing and Royal Gala come from Tianxing by AS-PCR. Tianxing and Royal Gala are more compatible to breed triploid cultivars. 4,The pollen shape and the chlorophyll content of different ploidy apple cultivars have obvious difference. With the decrease of ploidy, the chlorophyll content is increase, nevertheless the growth amount is decrease. The amount of pollen of every anther isn't orderliness. And there isn't different between the triploid and diploid cultivars. According to the number of pollen aperture, tetraploid and tripoid have obvious difference with diploid. Such as Hokato and Hac9 are N3-4P4C5 type.5,Method of body interstocks, head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to measure the composing factors of fruit quality and aroma compound of Honglu fruit on different cultivars body interstocks. The results showed that the firmness (7.02kg/cm2) and soluble solid sugar content (12.5%) of Honglu fruit on Fuji body graft were the highest compared with the fruit on other body graft. However, the firmness and SSC of Honglu fruit on Jonagold body interstock were the lowest, but its fruit weight was the highest (211.85g). The body interstock could not affect the number of aroma compounds of Honglu, but it could affect kinds of aroma significantly. The relative content of the same aroma category of Honglu fruit was different on different cultivars body interstocks. The contents of esters and alcohols were the highest (4.56% and 42.93%, respectively) on Fuji interstock, and they were the lowest on Jonagold body graft, 1.98% and 29.76% respectively. So grafting on Fuji body interstock could enhance the fruit quality of Honglu apple. |
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