Determination Of Physiological Indicators And Analysis Of Genetic Vairation Among Different Ploidy Watermelon

In this study, different ploidy watermelons (diploid, triploid crossed with4X×2X and autotetraploidinduced by colchicine) of Jiuhuaxi, Jinerlv and Chenghong3were test materials, and some physiology andbiochemistry characteristics of different ploidy watermelon materials were studied systematically, and amplifiedfragment length polymorphisms (AFLP) was used to study genomic DNA polymorphism of different ploidywatermelon materials and cDNA-AFLP was used to study the differences in the expression level on differentploidy watermelon materials. In different areas and levels, for example molecular biology, physiology andbiochemistry and so on, the relationships of the watermelon chromosome ploidy, the gene dosage and the traitexpression were investigated, providing an important theoretical basis for the polyploid breeding and resistancebreeding of watermelon. Through the experimental study, the following results were obtained mainly:1. The resistance of the polyploid was better than the diploid. The conductivities of the three watermelonvarieties were2X>3X>4X,3X and4X of Jiuhuaxi and Jinerlv, as compared with the corresponding2X, hadthe significant differences. The malondialdehyde (MDA) contents of three watermelon varieties were2X>4X>3X,3X and4X of Jiuhuaxi and Chenghong3, as compared with the corresponding2X, had thesignificant differences. The proline(Pro) contents of Jiuhuaxi were4X>2X>3X, the proline contents ofJinerlv and Chenghong3were4X>3X>2X,3X and4X of Jinerlv and4X of Chenghong3, as comparedwith the corresponding2X, all had the significant differences. The peroxidase (POD) activities in threewatermelon varieties were3X>4X>2X,3X and4X of Chenghong3, as compared with the corresponding2X,all had the significant differences.2. The chlorophyll(chlorophyll-a,chlorophll-b) contents of Jiuhuaxi and Chenghong3per unit freshweight leaf of watermelon were2X>3X>4X, and the chlorophyll contents of Jinerlv were2X>4X>3X,4Xof Jiuhuaxi and3X of Jinerlv, as compared with the corresponding2X, all had the significant differences.3. The prolycopene contents of the fruit of watermelon were relative to the color of pulp of fruit, and itwas mainly to be present in red pulp of fruit, the contents of Jiuhuaxi (red pulp of fruit) were4X>3X>2X, ascompared with the corresponding2X, polyploid all had the significant differences. The prolycopene contents of the yellow (Jinerlv) and orange (Chenghong3) pulp of fruit were extremely low, and there was not asignificant difference among the different ploidy.4. Using AFLP technology, we screened47pairs of primer combinations totally,28pairs of primercombinations did not amplify specific bands. The seven band forms were amplified among the different ploidyof each watermelon variety, and there were all the specific bands among the different ploidy watermelon.Jiuhuaxi amplified1063detected sites, and there were41polymorphic sites, accounting for3.86%. Jinerlvamplified1044detected sites, and there were18polymorphic sites, accounting for1.72%. Chenghong3amplified1054detected sites, and there were20polymorphic sites, accounting for1.90%. The resultssuggested that the polymorphism among the different chromosome ploidy watermelon was low in the genomicDNA level.5. Using cDNA-AFLP technique, we researched the different ploidy watermelon materials difference inthe level of the gene expression, we screened18pairs of primer combinations totally,4pairs of primercombinations did not amplify specific bands. The seven band forms were amplified among the different ploidyof each watermelon variety, and there were all the specific bands among the different ploidy watermelon.Jiuhuaxi amplified334detected sites, and there were53polymorphic sites, accounting for15.87%. Jinerlvamplified319detected sites, and there were32polymorphic sites, accounting for10.03%. Chenghong3amplified311detected sites, and there were17polymorphic sites, accounting for5.47%. The results suggestedthat among the different chromosome ploidy of three watermelon varieties, there was the widely geneticexpression diversity in the RNA level, and the polymorphism was higher than in the DNA level. As comparedwith the corresponding diploid, it occurred that the polyploid of the different watermelon varieties all had acertain percentage of the expression varieties about activation and silencing, but the regularity of activationand silencing was different in different varieties.