| Watermelon is one of the important fruits all over the world,and posessess a projecting position in the fruits of summer season.Its cultivating areas and total output is among the front ten fruits in the worldwide.But fusarium wilt is a main disease in the production of watermelon, which threats watermelon's production and quality seriously. Theory research and practice demonstrate that breeding the watermelon fusarium disease-resistant cultivars is a main way to resolve this problem, which includes differentiation of the isolates, identifying and collecting of resistant material,and resisrance heredity and disease-resistant mechanism. So making experiments on the genetic differentiation of Fusarium Oxysporum f. sp. niveum on the DNA level, and the genetic diversity of watermelon cultivars can provide theoretic foundation and methods to breed resistant cultivars and make full use of watermelon cultivars.In this research,we aim to study differentiation of Fusarium Oxysporum f.sp.niveum and genetic diversity of watermelon cultivars. Meanwhile, analyzing the relationship between differentiation and pathogenic type, and the relationship between genetic diversity and cultivars' resistant power.Based on the identification of specialization types and pathogenic types with Fusarium Oxporum f.sp. niveum, and disease-resistant results of cultivars. On one side, with 47 isolates from the main watermelon product area of Hebei province and physiologic race 1 from Beijing and physiologic race 0 and race 2 from Xinjiang,using RAPD method, we analyzed the differentiation of Fusarium Oxysporum f.sp.niveum. On the other side, we study the genetic diversity of 48 watermelon cultivars from different orign and with different resistance using AFLP.1.By random experiment thoroughly, with isolate FON6, we established RAPD technique system fit for Fusarium Oxporum f.sp. niveum, the concentration of random premier was 10u.mol/L, template 1.6mg/L, Taq DNA polymerase 1.25U, 10xbuffer 2.5uL, dNTPs 2mmol/uL. Meanwhile, we groped on the fitful annealing tempreture. It's 37C.2.50 isolates were analyzed on genetic diversity. The result indicated that therange of the similarity coefficient among the 50 isolates is from 0.45 to 0.93. And the average is 0.71. It indicated that there existed seriously genetic differentiation between these isolates of Hebei province apparently. Based on the result of RAPD clustering, 50 isolates were divided into 6 RAPD groups(RGs for short). They are RGI ,RG II,RG III,RG IV RG V and RGVI. And R.GVI was subdivided into 7 RAPD subgroups (RSGs for short). They are RSG1, RSG2, RSG3, RSG4, RSG5, RSG6, and RSG7. Different RGs or RSGs had different isolate number. RG I and RGII include only one isolate separately, RGlIIand RGV include two, RGIV include 5, others belong to RGVI.Among RSGs, from RSG1 to RSG3 include only one isolate separately, RSG4 and RSG5 include two, RSG6 include 19, and there were great differentiation among the 19 isolates, RSG7 include 13. There were different level of genetic differentiation. This study demostrates: (l)There were no correlation between RAPD groups or RAPD subgroups and watermelon fusarium wilt pathogenic types. (2) There were also no correlation between RAPD groups or RAPD subgroups and the isolates orign.3.With 11 paired premiers,48 watermelon cultivars were analyzed by clustering using AFLP. The result indicate that the range of the similarity coefficient among the 48 cultivars is from 0.32 to 0.95,and the average 0.82. The wide varient is only because of watermelon cultivar TeDaJingXin, which is different from other cultivars on heredity background. If ticking out TeDaJingXin, the similarity coefficient range from 0.59-0.95 among the other 47 cultivars. Which indicated that the genetic base of watermelon is narrow. By clustering, 48 cultivars were divided into 6 groups. They are group AG I AGII AGIII AG IV AG V and AGVI. AG I AG II and AGIII include only one cultivar separately, AGiV. include3, AGVinclude 20, AGVI include 22. AGVcan be subdivided into 3 subgroups. The...
|
PDF Full Text Request