RAPD And ISSR Analysis Of Genetic Diversity In Orna-mental Gourd Germplasm Resourse

Orna-mental gourds are also known as the pumpkin toys,which are originated from tropical area.It belongs to Cucurbita of Cucurbitaceae.Many of them are cultivars from Cucurbita pepo L.The economy organ of the pumpkin was the fruit of the plant.The brightly colored squash is perfect for cultivating in the greenhouse,it also can be used for landscaping.The interest in using the adorable Orna-mental gourd is increasing in recent years.The study on genetic polymorphism of germplasm resources in orna-mental gourds are beneficial to rational utilization of it.Molecular marker,which can directly reflect genetic polymorphism at DNA level, is a powerful tool to study genetic polymorphism of the orna-mental gourds.RAPD and ISSR markers have been popularized for their simplicity,rapidity,non-specialty among different genera and saving cost. In this study,28 kinds of orna-mental gourds cultivars.were analyzed by using RAPD and ISSR markers, adopting cluster analysis.The study shows the results as follows:1.The RAPD and ISSR analysis system were optimized:the concentration of Mg²⁺,dNTPs,Taq DNA Polymoerse,the template DNA and primers were 2.0mmol/L,0.15mmol/L,1.0U,20ng and 10pmol in the 20μL RAPD reaction system;the concentration of Mg²⁺,dNTPs,Taq DNA Polymoerse,the template DNA and primers were 2.0mmol/L,0.25mmol/L,0.5U,20ng and 10 pmol in the 20μL ISSR reaction system.2.12 RAPD primers were screened out form 300 RAPD primers for PCR amplification of the 28 kinds of orna-mental gourd DNA,from which89 bands were amplified from the primers.The polymorphic fragment bands and percentage were 73 and 82%.After the PCR amplification,the molecular weights were between 300bp and 3000bp.the bands after amplification were 5 to 11 of each primer,and the average number of bands were 7.4.The value of GS(genetic similarity indexes)was estimated between 0.31 and 0.99 of 28 materials based on the RAPD analysis and the average is 0.73.The polygenetic tree of the genetic relationship in 28 individuals was drawn.It showed that when the value of GS is from 0.72 to 0.76,28 kinds of orna-mental gourds materials can be divided into four categories. 3.13 ISSR primers were screened out form 100 ISSR primers for PCR amplification of the 28 kinds of orna-mental gourds DNA,from which 93 bands were amplified from the primers.The polymorphic fragment bands and percentage were separately 81%and 86%.After the PCR amplification, the molecular weights were between 300bp and 3000bp.The bands after amplification were 4 to 11 of each primer,and the average number of bands were 7.15.The value of GS was estimated between 0.33 and 0.99 of 28 materials based on the ISSR analysis,and the average is 0.68.The polygenetic tree of the genetic relationship in 28 individuals was drawn.It showed that when the value of GS is 0.67 to 0.70,28 kinds of orna-mental gourds materials can be divided into three categories.4.The correlative coefficient is 0.862 means of analyzing the value of GS of RAPD and ISSR,and the result came out outstanding.It showed that the application of RAPD and ISSR has very high consistency and credibility on analysis of genetic diversity in orna-mental gourd.5.The value of GS was estimated between 0.34 and 0.97 of 28 materials based on the RAPD and ISSR analysis,and the average is 0.70,which is between RAPD and ISSR,but it is of no significant difference.The polygenetic tree of the genetic relationship in 28 individuals was drawn.It showed that when the value of GS is from 0.70 to 0.74,28 kinds of orna-mental gourd materials can be divided into three categories.It is closely similar with the RAPD and the ISSR,Comparatively,it is more similar to the latter one.