Study On Genetic Diversity Of Rootstock Germplasm Resources From Main Mango Producing Areas By SSR Marker

Mango (Mangifera indica Linn.) is the important tropical and subtropical fruits. Anthracnose is one of the main diseases in mango production,postharvest and transport,.it harm to mango production and quality seriously, overcoming of anthracnose is the serious problem that mango production must face. So breeding cultivars and rootstocks resourses resisting anthracnose is very important.Our country have more abundant mango resourses, and there are no lack of cultivars or rootstocks resourses resisting anthracnose among these. But we are lack of analysis of the genetic diversity of these resources at present. The resourses has not been utilized fully. At first, this study first optimized the mango of the SSR system,and analysis the genetic diversity of 116 Tu mang resourses, lay the foundation for breeding cultivars resisting anthracnose in future.The main results were as follow:Using Chun Hwang as material, the concentration of Mg2+, dNTPs, Taq polymerase, template DNA and primer, influencing SSR-PCR of mango in five factors, were optimized by orthogonal design. The results showed the effective degree of the factors on the PCR reaction was in the order:template DNA> dNTPs> primer> Mg2+> Taq polymerase, a suitable 20μl SSR reaction system was established, and the system containing 10×buffer 2μl,80 ng template DNA,0.4 mmol·L-1 dNTPs,0.2μmol·L-1 primer,1.8 mmol·L-1 Mg2+ and 0.75 U Taq polymerase. Amplification program was:2 min 30 s at 94℃; then 35 cycles that consisted of 30 s at 94℃,45 s at the best annealing temperature of each primer,1 min at 72℃; follow by 5 min extension at 72℃. This system had well reproducibility and stability proved by time after time amplification practice.This study collect Hainan, Guangdong, Guangxi, and Yunnan 4 provinces,116 rootstock germplasm resources in mainly mango cultivated in China, and then this article analysed genetic diversity of 116 rootstock germplasm resources through the SSR molecular markers.There are 31 pairs of SSR primers were synthesized for amplifying the genonmic DNA.18 primers were successfully amplified and the amplification primers accounted for 58%.There are 193 bands were found to be polymorphic by 8% native polyacrylamide gel electrophoresis,and the overall polymorphic loci percentage was 95.54%. The number of bands per primer pair ranged form 3 to 21. Using the software of NTSYSpc2.1 to construction dendrogram, the results showed that, at the similarity coefficient of 0.62,Hainan,Guangdong, Guangxi and a parts of Yunnan of the local mango were grouped together, at the similarity coefficient of 0.83, Haian and Guangdong of the local mango were grouped together, so the genetic distance between populations and geographical distance have certain correlation. The results of cluster analysis showed that rootstock resources have large genetic distance among populations for 4 provinces, but the genetic distance is small within a population, have a low level of genetic diversity.