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2017 - 201912020 - 20211
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Subject: Plant Pathology × Author: Harmandeep Kaur × End date: 2022 ×
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    ThesisItemOpen Access
    Pathological and molecular variation in Puccinia triticina the incitant of leaf/brown rust of wheat and host resistance
    (Punjab Agricultural University, Ludhiana, 2021) Harmandeep Kaur; Jaspal Kaur
    Leaf/brown rust of wheat, caused by Puccinia triticina (Pt), is one of the most important diseases of wheat worldwide. To study the virulence pattern/ diversity of P. triticina, the surveys for leaf rust occurrence were conducted in Punjab during 2018-2021. SBS Nagar (Saroya block) Ludhiana west, Rupnagar (Anandpur sahib) and Gurdaspur were observed as hot spot areas for leaf rust of wheat and disease severity recorded was in the range of 5-40S at different locations. From virulence profiling of the leaf rust infected samples collected from Punjab, it was found that Pt pathotypes 77-5, 77-9, 77-13 (121R60-1,7 ) and 1R 31 are known to occur in Punjab with varied frequencies. Out of which the prevalence of pathotype 77-9 was maximum (62.85%) followed by 121R60-1,7(31.42%). The genetic diversity among Pt isolates was studied using SSR markers which demonstrated that the new pathotype (121R60-1, 7) is more closely related to the pathotype77-9. To know the effectiveness of Lr genes, the leaf rust differentials (Indian and in Thatcher background) and commercial wheat cultivars/ known Lr gene lines were scored against P. triticina infection at four different locations of Punjab (Ludhiana, Gurdaspur, SBS Nagar & Abohar). The lines carrying Lr genes; Lr 9, Lr 19, Lr 24, Lr 25, Lr 28, Lr 29, Lr 32, Lr 42, Lr 45, Lr 47, Lr 52, Lr 57, Lr 58, Lr 76 exhibited resistance against the most prevalent pathotypes (77-5, 77-9 and 121R60-1, 7) of P. triticina in Punjab. One hundread and ninty seven wheat germplasm lines were evaluated at the seedling stage as well as at the adult plant stage against these pathotypes. Based on the seedling reaction test and adult plant response at Ludhiana and Gurdaspur during 2018-2021, it was inferred that thirty six lines showed highly resistant reaction whereas twenty six lines were highly susceptible with AUDPC value >400 and FRS value >40S. DNA of all these test lines was amplified with Lr gene specific markers to identify the gene(s) present in these lines. Based on the molecular data and race specific infection response at seedling as well as at adult plant stage; the leaf rust resistance genes Lr 9, Lr19, Lr24, Lr25, Lr 28, Lr29, Lr32, Lr42, Lr45, Lr47, Lr52, Lr57, Lr58 and Lr76 were postulated in these lines. All stage resistance was imparted by the genes; Lr9, Lr19, Lr24 and Lr28 against prevalent Pt pathotypes in Punjab. The F3 and F5 generation of seven populations were evaluated against P. triticina from 2018-2021 under field conditions at PAU (Ludhiana). The genotypic ratio 1:2:1 and 1:1 for F3 and F5 population respectively fit significantly on the phenotypic data. For gene mapping the resistant and susceptible bulks along with resistant and susceptible parents were genotyped with 90K SNP chip Ilumina array. The SNPs located on the chromosome 5A for population (IC 321853 X HD 3086); 7B for population (IC 549520 X HD 3086); 1B,1D and 6A for population (IC 252609 X HD 3086); 1A, 1D, 3B, 4B and 5A for population (IC 252742 X HD 3086) and 1A, 1B, 2B, 3B and 7A for population (IC 539316 X HD 3086) were selected for designing the KASP markers.
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    Virulence spectrum of puccinia striiformis f. Sp. Tritici in Punjab
    (Punjab Agricultural University, Ludhiana, 2017) Harmandeep Kaur; Jaspal Kaur
    Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating disease of wheat worldwide. The purpose of this research was to survey Punjab fields to determine the prevalence of stripe rust, characterize the race structure of Pst on the basis of virulence and to know the molecular diversity of the pathogen population. During the year 2014-2015 disease severity was in the range of 5-60 per cent in Rupnagar while 10-20 per cent in other areas. During the crop season 2015-16 maximum disease severity was in the month of December i.e.10-40 per cent in Rupnagar followed by traces to 40 per cent in SBS Nagar and 20 per cent in Hoshiarpur, Gurdaspur, Fatehgarh Sahib and 10 per cent in Ludhiana, Patiala on different cultivars. Race characterization was done by inoculating differential lines carrying known resistance genes along with 15 supplemental cultivars with 12 Pst isolates collected from hot spot areas of Punjab along with pathotypes 78S84, 46S119 and 110S119 obtained from IIWBR, Regional station, Flowerdale, Shimla. On the basis of their reaction on differentials, 3 races namely 46S119, 110S119 and 238S119 were identified. Genes Yr1, Yr5, Yr10 conditioned resistance against all isolates tested on differentials and all isolates were virulent on Yr2, Yr3, Yr4, Yr6, Yr7, Yr8, Yr9. Variation for virulence was observed among isolates on YrSD, YrSU and Yr9+. Out of fifteen (15) supplement genotypes, six (6) genotypes namely PBW729 (Yr15), PBW730 (Yr10), BWL2763 (Yr15), BWL3277 (Yr5), BWL3558 (Yr5), BWL4405 (Yr10) having resistance genes Yr5, Yr10, Yr15 were recorded highly resistant. PBW 343 showed ‘highly susceptible’ reaction against all isolates of Pst with maximum disease severity of 80 per cent and minimum incubation period of 8-9 days. Molecular diversity (based on SSR polymorphism) showed that isolates collected from Punjab were more diverse than isolates obtained from IIWBR, Regional station, Flowerdale, Shimla. On the basis of SSR primers (SOB, PAU, Ludhiana) result revealed that previous year isolates were genetically different than current isolates.