Studies Of Molecular Marker Linked To Grafting Compatibility In Melon

In this paper, two melon varieties(85-1and B717), being significant differences in grafting affinity with the pumpkin rootstock’a strong man’, were used as parents to construct F2and F23populations; Based on differential DNA pools in grafting affinity, The method of BSA (Bulked Segregant Analysis) combining SSR (Simple Sequence Repeat) was used to detect the molecular markers lingked to the graft compatibility. The main discusses were as follows:1. The F2generation including126individuals produced from the cross between inbred lines85-1and B717of Melon varieties. Using cleft grafted F2singles with the pumpkin root stock’a strong man’respectively and the survey of grafting affinity found that:Compared with the roots grafted plants, the affinity performance of melon scion85-1with pumpkin root stock’a strong man’was optimized (0level), and survival rate reached as high as99%, fruit-setting rate was100%, fruit sweetness without change, the overall quality stayed the same with control; while B717survival rate was only40%(3level), fruit-setting rate was56%, fruit sweetness reduced by2.8%than the contrast, and the overall quality was poor. This suggests that the grafting affinity of melon85-1with pumpkin root stock’a strong man’was higher, and grafting affinity of B717was poor. Meanwhile, the grafted plant of F3family as scion (F2singles as compared) have a performance of separation in the grafting affinity (survival rate, fruit-setting rate, fruit sweetness).2. The genetic DNA of melon was extracted by the method of modified CTAB via collecting each10DNA of F2corresponding melon scions, which graft compatibility performance respectively were optimal (level0) and poor (level3). It showed that the quality of DNA extraction was good and can be used for PCR reaction system through the detection of0.8%agarose gel electrophoresis. Finally, Each of3DNA pool of best and poor in grafting affinity were contrusted respectively using BSA method for primer polymorphism screening.The SSR reaction system was optimized in this research, confirming the stable reaction system for25μL:2x EasyTaq PCR Master Mix12.5μL, DNA template1μL, each of forward and reverse primer1μL and added9.5μL ddH2O to the total; The PCR amplification procedure was that:pre-denature at94℃for3min,94℃modified30s,55℃refolding30s,72℃extension1min, for35cycles, the last72℃for5min. The PCR amplification tested with1.5%agarose gel electrophoresis,120V,90min was stable and reliable.3. The382primers with polymorphism in two melon parents were screened from750pairs of SSR primers, which had published in the cucurbitaceae genetic linkage map. There are9pairs of primers that can respectively amplified different fragments in differential DNA pools in grafting affinity; Only2primers(M103and CMN-0616) polymorphic markers were selected after detection and verification using F2population, and showed that the distance of markers both linked to grafting affinity with the genetic were9.3cM and17.6cM respectively.Two markers related with the gene of grafting affinity in melon were screened out in this experiment using the method of SSR molecular marker, which provides a rapid and effective way for melon grafting affinity screening, and plays a positive role in accelerating molecular plant breeding process of melon grafting affinity.