Study On Biology Of Spores Formation And Pathogenic Differentiation And ISSR Polymorphism Of Pseudopeziza Medicaginis

The objective of this paper is to study on biology of spores and apothecium formation and host category of pseudopeziza medicaginis; to establish the differentiate hosts system on the base of different pathogen;to study relativity of ISSR polymorphism and pathogenecity by using clustering analysis for issr polymorphic marker of pseudopeziza medicaginis.1. Effect of temperature, carbon, nitrogen, light and media on sporulation of pseudopeziza medicaginis were studied.The results showed that V8-CaCO3 and juice of alfalfa culture medium were the best medium for apothecium. P. medicaginis could not form apothecium on different types of carbon and nitrogen source culture medium.The optimum range of temperature was 25℃-28℃. The optimum illumination time was 2000 lux. P. medicaginis were not sporulate on the condition of artificial culture.2.The virulence and infectivity of Pseudopeziza medicaginis to some lequminosae were observed by means of artificial inoculating pathogens of P. medicaginis to fourteen spieces of five category. The results showed the hosts of P. medicaginis were Medicago sativa, Medicago varia, Medicago falcate, Melilotus medic, Melilotus officinalis and Melilotus Mill. P. medicaginis could sporulate on Medicago L and Melilotus Mill .It showed that P. medicaginis is host specialization and take sexual stage in Medicago L. and Melilotus Mill..3. A set of Alfalfa germplasms were screened as P.m(Pseudopeziza medicaginis) pathogen differential hosts which were currently cultivated in China , such as M.sativa Baoji , M.sativa Jingyang, M.sativa Shawan , M.sativa Shahe, M.sativacv.Jinnan , M.sativacv.Tianshui, M.sativacv. TumuNo.1 , M.sativa Baoding and M.sativacv.Iroquois.4.Sever P.m strains were classified into five pathogenecity groups through identification at adult stage according to disease severity on differential host. Among pathogenecity types we detected, the pathogenicity type A appeared to be highest virulence to host plants , and pathogenicity type E was weak one , pathogenicity types C, D and G were in middle place.5.The relationship of genetic diversity,virulence and geographical origin were studied.The analysis showed that there were abundant genetic diversity among Pseudopeziza medicaginis, and the genetic variation was very significant from different area.The ISSR clustering groups had correlation with virulence variation,but virulence variation had no significant correlation with geographical origin and with ISSR groups.