Genetic Diversity Analysis By AFLP Markers And Identification Of Disease Resistance By Inoculation Of Phytophthora Nicotianae For Agave Germplasm

Agave, commonly known as sisal is the most important fibre crop in the south subtropical and tropical regions in China and the world. However zebra leaf spot caused by Phytophthora nicotianae is the most common and serious disease of sisal.In this paper, we did researches on the genetic diversities used fluorescence AFLP molecular marker and the resistance to Phytophthora nicotianae for 40 agave germplasms collected from home and abroad, including 14 materials without any genetic background. The following results achieved from this study will provide the basis for new sisal varieties selecting and breeding with disease-resistance.1. Compared two methods for sisal genomic DNA extraction. The result showed that the improved CTAB is better than the Resin extraction, with clearer bands, higher purity and output of DNA.2. Established a modified reaction system of fAFLP (fluorescent Amplification Fragment Length Polymorphism) suitable for sisal genetic diversity analysis.3. Compared the digesting effect of two paired restriction enzymes for sisal genomic DNA. The results showed Pst I/Mse I is better than EcoR I/Mse I with more and clearer bands in selective amplification.4. Using Pst I/Mse I paired restriction enzymes, 8 paired primers with good polymorphism were selected from 64 for AFLP. Total 785 AFLP bands were detected including 507 polymorphic bands. The polymorphic frequency is 64.58%. 88 to 117 polymorphic bands could be amplified from each primer, with an average of 98 bands.5. The cluster analysis based on the data of AFLP showed that all the tested materials were clustered into four groups at similarity coefficient level 0.51. Group I included A.attenuata, A.attenuata var, A.fourcroydes, A.cantala and filial generation of A. sisalana×A.hybrid No.11648 and A.hybrid No.11648×A.americana. Group I also could be clustered into five subgroups at similarity coefficient level 0.61. The first subgroup included A.attenuata and A.attenuata var. The second subgroup included A.sisalana var Yuexi, A. sisalana, A.hybrid Yuexi No.114, A.hybrid Yuexi No.75, A.hybrid'Dongfang hong No.16'and Muoyin No.5. In this subgroup, A.hybrid Yuexi No.114, A.hybrid Yuexi No.75 and A.hybrid'Dongfang hong No.16' were the filial generation of A. sisalana×A.hybrid No.11648. The third subgroup included A.cantala and A.fourcroydes. The forth subgroup included A.americana, Dong No.292,Muoyin No.6, A. hybrid D.h.No.368, A.hybrid Nanya No.1, A.hybrid Nanya No.2, A.hybrid No.76416 and Muoyin No.8. In this subgroup, A.hybrid 76416 and A. hybrid D.h.No.368 are the filial generation of A.americana×A.hybrid No.11648; A.hybrid Nanya No.1 and A.hybrid Nanya No.2 were...