Analysis On Genetic Diversity And Disease Resistance Of Medicago Varia Martin. By Sequence-Related Amplified Polymorphism Markers

SRAP (Sequence-related amplified polymorphism) molecular markers were used to detect the genetic diversity and disease resistance of 31 accessions of Medicago varia Martin, from China (Xinjiang), Kazakhstan, and Poland, etc.Basing on the SRAP marker system establishment, we take a study on the genetic diversity and disease resistance of tested materials.This research aims to explore the genetic variation and relationship for these germplasm resources,to identify the link of the material resistance and the genetic background,and to provide a theoretical basis to molecular marker assisted selection.The results as follow:1. One of the most suitable 25μL SRAP-PCR systems for Medicago varia Martin, containing dNTP 2μL(0.20mmol/L),Taq DNA polymerase 0.3μL (1.50 U),Mg2+3μL(1.50 mmol/L),each primer 1μL (0.40μmol/L),50ng DNA template 1μL and 10×PCR buffer 2.5μL (exclusion Mg2+) was established. We found out the annealing temperature is 52℃for SRAP-PCR and 35 cycles for PCR reaction procedure. The optimized SRAP-PCR system was tested on four Medicago varia Martin. germplasms,17 primer combinations were selected with abundant polymorphism from 60 primer combinations.2. Studying on the 31 accessions,17 pairs of primer combinations detected a total of 179 bands, and each pair of primers amplified 8.41 polymorphic bands in average. The percentage of polymorphic bands (PPB) was 79.89%.The Nei's genetic similarity coefficient of the tested accessions ranged from 0.59 to 0.874 and the average Nei-Li's coefficient was 0.723. These results suggested that there were rich genetic diversity with the Xinjiang resources comparing to the Central Asia and Europe's resourse. The result from the UPGMA cluster analysis reflected that materials could be divided into 3 groups.3. Disease resistance evaluation results as follow:six germplasms showed high resistance to stemphyllium leaf spot from China (Xinjiang),Kazakhstan and other countries; No.4 and No.9 material the immunity of the root rot; No.1 and No.28 material showed a higher resistance to both. Most of Materials from Central Asia showed no resistance to root rot but high resistance to stemphyllium leaf spot, and most of materials from Europe showed resistance to root rot but not resistance to stemphyllium leaf spot features. Studying on the disease resistance of stemphyllium leaf spot and root rot with 17 pairs of high polymorphism SRAP primers. There are two molecular markers named F14-r14450 and Mel-r14500 which relatively high correlation resistance to stemphyllium leaf spot,one molecular marker named Me4-em4700 which relatively high correlation resistance to root rot.