الفهرس 
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Abstract
Production of new improved varieties of mushrooms with higher yield and quality as well as resistance to diseases are the major aims for mushroom breeders and mushroom research. Breeders now use DNA molecular markers to identify and select specific genes to locate superior traits from wild isolates and expand the genetic base of the cultivated mushroom. In this study, we induced mutation for improvement of Calocybe indica strains by applying gamma radiation with six different doses, including 0 as control, 10,250,500,750 and 1000 gray on C. indica mycelia grown on PDA. By using different doses; post radiation observation on the mushroom morphology, twelve morphological parameters, chemical analysis, protein electrophoresis and genetic similarity using the ISSR PCR polymorphic bands were measured and analyzed the genetic diversity of five different isolates of mushroom (AB , Po , CI-1, CI-2 and CI-3) belong to three species (Agaricus bisporus , pleurotus ostreatus and Calocybe indica ) using six SSR loci. The results obtained from Strain improvement of Calocybe indica confirmed the existence of different response of three strains of milky mushrooms to different doses of radiation. When measured 14 days after irradiation, strain CI-2 take less time to complete mycelia growth and mycelial growth of cultures treated with low dose (10 gray) was faster than other that of unirradiated cultures. High doses (250,500,750,1000 gray) inhibited mycelial growth significantly. The strain CI-1 gave the highest yield , B.E % , the smallest cultivation period and the largest number of fruits . Irradiation dose 750 gray gave the highest yield, B.E. % and the largest number of fruits bodies. Mutants showed wide range of variability, whereas mutant CI1(250 gy) gave the highest yield (746.67 g) , B.E % (149.33%) and the highest number of buttons (12.67) . These results confirmed the important of mutant CI-1(250gy) followed by CI-1(750gy) in next breeding and production programs for milky mushroom (calocybe indica). All the mutants (100%) yielded a remarkable increase in total protein , whereas mutant CI-3 (10 gray ) gave the highest total protein content (26.14 ± .02 %). 73% of mutants yielded a remarkable increase in total carbohydrates , whereas mutant CI-1 (250 gray ) gave the highest total carbohydrates content (27.55 ± .81 %). 60 % of mutants yielded a remarkable increase in total phenols ,whereas mutant CI-1 (10 gray ) gave the highest total phenolic content (12.05 ± .72 %). 93 % of mutants increase antioxidant activity in terms of radical scavenging activity on the DPPH free radical ,whereas the highest antioxidant activity in terms of radical scavenging activity on the DPPH free radical were mutant CI-3 (10Gy) ( 10.37 ± 0.23 ) followed by mutant CI-2(1000 gy) ( 7.94 ± 0.25 % ) compared to their controls 6.3 ± 0.01 and 5.19± 0.74 , respectively . 73% of mutants yielded a remarkable increase in vitamin C content , whereas mutant CI-2 (250 gray ) gave the highest vitamin C content (73.15 mg/100g) when compared to all controls and other mutants. The content of ca (0.73 %) and k (26.54 ppm ) of strain CI-3 is higher than other strains , Se content of CI-1 (3.5 ppm) is slightly high compared to other strains whereas, applied irradiation doses did not show a systematic effect on the elements profiles. SDS-PAGE analysis of the investigated mushrooms proteins has demonstrated a great heterogeneity in the separated protein fractions. An extra number of bands of protein was observed in mutant CI-1(10 gy) in comparison to wild strain CI-1 (0gray) So , it can be said that these proteins might be playing a major role in the mycelia radial growth of irradiation dose (10 gray). ISSR analysis revealed that gamma irradiation effect on DNA variation of C.indica strains in varying degrees yielding 58 bands including 40 polymorphic bands. Polymorphic information content (PIC) was estimated for each primer and ranged from 0.10 for primer HB- 15 to 0.356 for primer 49A , with a mean value of 0.23 . Jaccard’s similarity index of sample pairs varied from 0.510 between genotypes CI2(10gy) and CI2(1000gy) to 0.896 between genotypes CI2(750gy) and CI3(250gy) suggesting high level of genetic variability in the strains and their mutants. Results obtained from SSR analysis showed that, a total of 19 alleles were detected; of which 18 (94.7%) were polymorphic. Polymorphic information content (PIC) values ranged from 0.36 to 0.75 with a mean of 0.53 showed existence of high genetic variation between mushroom isolates. Based on cluster analysis , mushroom samples could be divided into three major groups whereas, milky mushroom strains (CI1 , CI2 and CI-3) could constitute one group. The SSR amplified alleles can be used as markers for identification of mushrooms and the information on the genetic relatedness presented here will be useful for breeding programmers for detection of duplicate sample and selection of parent strains to avoid inbreeding depression. This study indicated that 1) the strains of Calocybe indica and their mutants show abundant diversity in morphological, genetic diversity and chemical analysis, 2) DNA polymorphism detected by ISSR analysis offered a useful molecular marker for the identification of strains and mutants in gamma radiation-treated mushroom and that 3) mushroom microsatellite markers can be used to efficiently distinguish mushroom genotypes and to estimate their genetic diversity.