Molecular and Agro-physiological Study Associated with Net Blotch Resistance at Seedling and Adult Plant Stages in Some Egyptian Barley Genotypes

Net blotch infection is the most widespread and harmful disease for barley that caused substantial losses grain yield and quality, in this study Greenhouse and field experiments were carried out to recorded the net blotch reaction at seedling and adult stage of twenty barley genotypes during two growing seasons 2020/2021 and 2021/2022 .Start Codon Targeted (SCoT) markers were used to study the genetic variances and relationships among barley genotypes against net blotch reaction. The expression of severity to net blotch infection based on agro- physiological traits and net blotch reaction studied showed that Line 3 and Giza 2000 genotypes appeared the highest net blotch infection response that had lowest phenol content, chlorophyll fluorescence (FV/FM ratio) and total chlorophyll content SPAD were (42.52 mg/100g 0.510, 39. 53 SPAD reading and 43.76 mg/100g, 0.543 and 40.50 SPAD reading) respectively. However Giza 132, Giza 134, Giza 137, Giza 136, Line 4, line 5 and line 7 were proved to be the most resistant genotypes for net blotch that showed high average mean performance values for all studied agro- physiological traits over all the tested barley genotypes and scrod one under greenhouse at seedling stage with lowest net blotch infection that they were related to type R. Genetic changeability and associations among 20 barley genotypes based on using ten SCoT markers showed 77 amplified fragments, out of them 61 (77.92%) were polymorphic. The primer (SCoT -9) was highly informative marker which had higher values of total number of bands, number of polymorphic bands, polymorphism percentage, Polymorphism information content, diversity index, marker index and discriminating power DP were ( 10 ,9, 90.0, 0.389, 0.489, 0.499 and 0.692 ) respectively, so we could consider that useful primer to confirm the genetic differences among barley genotypes for net blotch reaction. The dendrogram based on SCoT showed clear pattern of clustering among the twenty barley genotypes with the resistant and susceptible for net blotch. These results could be useful for barley improvement in terms of biodiversity protection and design of new crosses for disease resistance to net blotch resistance in Egypt.