Genetic Diversity Analysis Of Watermelon Germplasm Based On SSR Molecular Markers And Morphological Markers

Watermelon(Citrullus lanatus)is one of the most important cultivated cucurbit watermelon plants in China.It originated from the "Silk Road" from the Middle East to China.The main methods of cultivating watermelon varieties in our country are direct introduction or hybrid of fine characters.At present,most of the hybrid breeding of watermelons only use solid.Several good varieties were bred as parents,and the parent origin was similar to the breeding of watermelon varieties,and the genetic diversity would lead to the degradation of watermelon varieties to affect the quality and yield.In general,the genetic diversity of watermelons is generally evaluated by phenotypic traits,but the phenotypic traits are often affected by the environmental conditions,and it is difficult to distinguish a large number of homologous crops from a short period of time by only one character.Therefore,it is very difficult to identify and identify a large number of Watermelon Germplasm Resources solely by phenotypic traits.Cytological markers,biochemical markers and molecular markers were developed after morphological markers.The molecular markers have the advantages of high reliability,not easy to be affected by the external environment,rich in polymorphism and high efficiency.Therefore,the genetic diversity of 276 watermelon germplasm resources is analyzed by combining the SSR molecular markers in molecular markers and phenotypic traits.11 stem,leaf and fruit related phenotypic traits are used in this experiment.The average variation coefficient was 0.26,and the variation coefficient of peel thickness was the largest,and the average diversity index was 0.57.In the SSR molecular marker,23 pairs of core primers were used to test 276 parts of the material,and 6571 bands were clearly identified.The size of the bands amplified by PCR was 100-300 bp.Each pair of primers could amplify 7-132 polymorphic bands,and the average of each pair of primers could amplify about 35 polymorphic bands.The source places are divided into five types.