P.V. PATILAMMAJAMMA, R.2019-02-212019-02-212007-01-03TH- 8362http://krishikosh.egranth.ac.in/handle/1/5810096395FACTORS OF RESISTANCE TO SOYBEAN RUST CAUSED BY Phakopsora pachyrhizi Syd. AMMAJAMMA, R. 2005 P.V. PATIL MAJOR ADVISOR ABSTRACT The present investigation deals with the identification of biochemical factors of resistance and enzymatic activities as influenced by rust caused by Phakopsora pachyrhizi Syd. in two resistant (EC 241778 and EC 241780) and two susceptible genotypes (JS 335 and DSb 1) of soybean at 45 and 75 DAS. Also the characterization of these genotypes through DNA fingerprinting by RAPD technique was carried out. The study indicated that at both the intervals, the resistant genotypes had more of total phenols, sugars (reducing, non-reducing and total sugars) and chlorophyll content (Chl-a, Chl-b and total chlorophyll) than susceptible genotypes. But due to infection the per cent increase in total phenol was maximum in susceptible genotypes. However the quantity of sugars and chlorophyll content were decreased in diseased leaf than healthy ones. Analysis on isozyme pattern revealed that, only at 75 DAS both peroxidase and polyphenol oxidase shown polymorphic bands, which indicated the need based synthesis of isozymes. The activities of phenylalanine ammonia lyase and tyrosine ammonia lyase were found similar. However from initial to final stage the activity was found increasing in resistant genotypes where as decreasing in susceptible genotypes. RAPD profiles for four genotypes were generated with 60 random primers out of these OPB-8 and OPB-17 shown polymorphic bands in both resistant genotypes but absent in susceptible genotypes. Similarly other six primers shown polymorphism in both the susceptible genotypes but not in resistant genotypes. Therefore these primers can be tested with large number of genotypes to identify the consistent cosegregation between polymorphic band and disease resistance / susceptibility to utilize them in marker assisted selection programme.ennullThesis