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Thesis

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2020 - 202122
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Subject: Plant Pathology × End date: 2021 × Start date: 2020 × Type: Thesis ×
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    Epidemiology and Management of Post harvest diseases of Kinnow mandarin
    (Punjab Agricultural University, Ludhiana, 2021) Gurwinder Kaur; Raheja, Sandeep
    Surveys were conducted periodically (twice in a month) from January to March during 2019 and 2020 to record the incidence and prevalence of major post-harvest rots of Kinnow mandarin and pathogens associated with it in South-western Punjab. Highest incidence of post-harvest rot of Kinnow mandarin 20.21 and 12.59 percent was observed in the month of March during the year 2019 and 2020, respectively. Penicillium digitatum and Penicillium italicum causing green and blue mould rots were found to be two most prevalent post-harvest pathogens with their prevalence of 30.88 and 26.44 percent, respectively during 2019 and 32.44 and 24.88 percent, respectively, during 2020. Temperature of 25˚C favoured maximum radial growth (84.67 mm) of both test pathogens also, maximum percent disease index of green (95.00 percent) and blue mould rot (90.00 percent) was recorded at 25˚C. The pH 5.5 and 6.0 supported maximum radial growth of P. italicum by 90.00 & 88.66 mm and of P. digitatum by 88.67 & 87.67 mm, respectively and were found to be at par with each other. Among different GRAS chemicals and botanicals evaluated against test pathogens, copper sulphate, boric acid, sodium bicarbonate and sodium carbonate at 100mM and above concentrations among chemicals and garlic extract at 10 per cent and above concentration among botanicals showed complete inhibition (100.0 percent) of both test pathogens under in vitro, whereas, under in vivo garlic extract at the concentration of 15 percent showed complete inhibition of green (100.0 percent) and of blue mold rot (92.22 percent). Boric acid at the concentration of 4 percent showed complete inhibition (100.0 percent) of both the test pathogens.
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    Management of Sclerotinia stem rot of rapeseed mustard using plant defense inducers
    (Punjab Agricultural University, Ludhiana, 2021) Sudam, Shelke Saraswati; Sandhu, P.S.
    The stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the major diseases of rapeseed-mustard. In this study, plant defense inducers salicylic acid and sodium propionate, fungicide azoxystrobin, carbendazim and bio-control agents Trichoderma harzianum and Pseudomonas fluorescens were evaluated for the management of Sclerotinia stem rot of rapeseed-mustard. These treatments were given as seed cum foliar treatment and foliar sprays alone. In field trials conducted during 2019 and 2020, the highest per cent reduction in mean lesion length was in carbendazim @0.2 per cent as seed treatment cum foliar spray, which was 56.76 and 80.81 per cent during 2019 and 2020, respectively. It was followed by application of 100 ppm azoxystrobin as seed treatment cum foliar spray that gave 35.14 and 64.18 per cent reduction during 2019 and 2020, respectively. Under in vitro conditions carbendazim completely inhibited the growth of the pathogen at all tested concentrations followed by 150 ppm salicylic acid which inhibited growth by 49.44 per cent. The bio-control agent T. harzianum showed antagonistic activity against S. sclerotiorum and restricted growth by 45.19 per cent. The biochemical studies showed that application of 150 ppm salicylic acid as seed cum foliar spray resulted in increased activity of POD which was 217.61 units/ min/ gfw and SOD activity which was 60.09 units/ min/ gfw at 72 hours after inoculation. The PAL enzyme activity was found to be highest at 120 hours after inoculation which was 765.05 µg-t-cinnamic acid formed/ hour/ gfw. The lignin content and total phenol content was increased at 168 hours after inoculation which was 24.40 mg/g and 1.82 mg/g respectively. In quantitative expression analysis, the significant increase in activity of BjPAL and POD genes was observed at 72 hours after inoculation when compared with control. This suggests that seed treatment and foliar application of plant defense inducers are effective for induction of defense responses against S. sclerotiorum in rapeseed-mustard.
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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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    Understanding virulence spectrum of Rhizoctonia solani under rice-potato cropping system
    (Punjab Agricultural University, Ludhiana, 2021) Thakur, Ajaysingh; Lore, Jagjeet Singh
    Sheath blight of rice, caused by Rhizoctonia solani is significantly reduces grain yield and quality of rice. The pathogen is a soil borne having wide host range which infect potato causing black scurf. Field surveys were conducted in different districts of Punjab during year 2019-20. The survey revealed that severity of rice sheath blight found maximum in Ludhiana and minimum in Hoshiarpur district. The main aim of the study was to find out the cross infectivity of the pathogen and to study the variations occurring in the pathogen with respect to morphological, pathological and molecular aspects. Fifty Rhizoctonia isolates showed large variation with respect to morphological and cultural characteristics which were grouped into seven major clusters. For pathological characterization, all Rhizoctonia isolates were inoculated on rice genotypes viz Tetep, J-85, D-256, D-6766, PR-108, PR-126 and Te-Qing and potato varieties namely Kufri Pukhraj and Kufri Jyoti. Five different groups were identified based on virulence pattern such as avirulent, least virulent, moderately virulent, virulent and highly virulent. Two isolates P-1 and P-2 belonged to group A were avirulent on rice genotype. Group E consisted of twelve isolates which showed highly virulent with disease severity of 53.9 to 70.0 per cent. Tetep showed the lower disease severity of 38.5 per cent. Molecular characterization of Rhizoctonia isolates was done using species specific markers, AG subgroup specific markers and ISSR primers. Out of three Rhizoctonia species (R. solani, R. oryzae-sativae and R. oryzae), R. solani was found dominant in Punjab state. The Rhizoctonia isolates collected from rice sheath blight, belonged to AG1-IA and two isolates from potato were classified as AG3-PT. Genetic diversity of Rhizoctonia isolates using ISSR primers found higher degree of PIC value ranging from 0.69 to 0.90. On the basis of genetic diversity and marker index, primer R25 considered as highly informative and R19 as least informative marker. On the basis of morphology and virulence, re isolates from potato showed greater variation with original rice isolates. The genetic structure of Rhizoctonia isolates and species in mixed infection is being thoroughly investigated for better understanding of pathogen adaption to facilitate in the disease resistant breeding program.
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    Biology of Ustilaginoidea virens (Cooke.) Takahashi and mapping QTL for resistance to false smut in rice (Oryza sativa L.)
    (Punjab Agricultural University, Ludhiana, 2021) Kamboj, Ishwinder; Lore, Jagjeet Singh
    The false smut of rice is caused by fungus Ustilaginoidea virens (Villosciclava virens). The disease causes 0.2-49% yield losses besides qualitative losses. The knowledge of disease cycle about the pathogen and the availability of resistant sources for false smut is lacking. The present study was conducted with various treatments for seed-borne, soil-borne and air-borne nature of primary inoculum in pot experiment. The disease incidence and percent infected panicles was more in case of plants with uncovered panicles (10-36%) than covered panicles (0-9%), in infected soil (9-33%) than in sterilized soil (8-13%) and in case of plants raised from infected seed (0-10%) than from healthy seed (0%). The percent infection was the highest in case of air-borne experiment in plants with uncovered panicles than in plants grown in infected soil whereas the plants raised from infected seeds reported only 5% infection. In another experiment, screening of 212 rice accessions against false smut disease under field conditions resulted in selection of 27 resistant lines. These lines were further screened under artificial conditions against the disease along with susceptible checks (GSR123 and PR116) resulted in selection of 19 resistant lines. Out of 19, the lines CANAROXA and IAC 47 with good agronomic trait were used as donors for preparing crosses with PR126 and PR116, respectively. Out of 78 SSR markers, the markers which show polymorphism in PR116  IAC 47 includes RM16493, RM18457, RM25149 and RM28404 on chromosome 4, 5, 10 and 12, respectively. On the other hand, the polymorphic markers in case of PR126  CANAROXA includes RM104, RM289, RM7434, RM8243, RM264, RM25149, RM10 and RM26643 on chromosome 1, 5, 6, 8, 10 and 11, respectively. These polymorphic markers were used to identify genetic diversity in the mapping population. However, the identified polymorphic markers in this study fail to depict the association between the marker and false smut resistance gene due to lack of definite pattern of markers at loci. Further analysis in next generation will help us to uncover the association between the marker and the false smut resistance gene.
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    ThesisItemOpen Access
    Yellow mosaic disease resistance in Vigna species and potential green bridges for legumoviruses in Punjab
    (Punjab Agricultural University, Ludhiana, 2021) Rohan Kumar; Sirari, Asmita
    Yellow Mosaic Disease (YMD) is reported to be the most destructive viral disease on mungbean caused by Yellow mosaic Virus belonging to genus Begomovirus of the family Geminiviridae. Development of YMD resistance in cultivated mungbean varieties remained unsuccessful due to highly variable nature of pathogen. In present study, 12 wild accession of mungbean and various weeds were collected. In different wild accession level of resistance were analysed in natural field condition and in artificial condition, samples were subjected to specific primers of LYMV (MYMV/MYMIV) out of 12 wild accession 4 accession were showing HR (high resistance) Vigna umbellata (GP1), V. radiata var satulosa (GP11) V. sublobata (GP2) and V. sublobata (GP12). All accessions showed presence of whitefly but count on HR accession (Vigna umbellata (GP1)(11.66), V. radiata var satulosa (GP11)(9.33), V. sublobata (GP2)(10.00) and V. sublobata (GP12)(12.13)) was less than susceptible check(SML 1082)(23.66). 36 weeds were collected from different locations of Punjab and were subjected to RCA and out of 36 samples 9 samples were amplified specific band size 2.8kb afterward these sample subjected to LYMV specific primer (MYMV/MYMIV). All 9 samples showed presence of MYMIV virus but MYMV virus was not present in any sample. Then to know the presence other virus in these 9 samples. Keeping this in view, in present study, the degenerate primers PALIc1960 and PARIv72 were used to amplify the RCA enriched DNA of weeds. All nine weeds showed association of Begomoviruses, confirmed with amplicon of ~1.2bp. Further, these amplicons were sequenced for characterization of Begomoviruses harbouring in weeds during off season by outsourcing from Agri Genome Pvt. Ltd. The nucleotide-BLAST results of sequences revealed the presence of Tomato leaf curl Palampur virus in Baru (Sorghum halepense), Ivy gourd, (Coccinia grandis), Leh, (Cirsium arvense), Button weed, (Malva parviflora), Jangli halon (Coronopus didymus), Maina (Medicago polymorpha) and Tik weed (Tridax procubens), while Billygoat weed (Ageratum conyzoides) and Sadabahar (Catharanthus roseus) showed presence of Ageratum enation virus and Papaya leaf curl virus respectively.
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    ThesisItemOpen Access
    Epidemiology and Management of Post harvest diseases of Kinnow mandarin
    (Punjab Agricultural University, Ludhiana, 2021) Gurwinder Kaur; Raheja, Sandeep
    Surveys were conducted periodically (twice in a month) from January to March during 2019 and 2020 to record the incidence and prevalence of major post-harvest rots of Kinnow mandarin and pathogens associated with it in South-western Punjab. Highest incidence of post-harvest rot of Kinnow mandarin 20.21 and 12.59 percent was observed in the month of March during the year 2019 and 2020, respectively. Penicillium digitatum and Penicillium italicum causing green and blue mould rots were found to be two most prevalent post-harvest pathogens with their prevalence of 30.88 and 26.44 percent, respectively during 2019 and 32.44 and 24.88 percent, respectively, during 2020. Temperature of 25˚C favoured maximum radial growth (84.67 mm) of both test pathogens also, maximum percent disease index of green (95.00 percent) and blue mould rot (90.00 percent) was recorded at 25˚C. The pH 5.5 and 6.0 supported maximum radial growth of P. italicum by 90.00 & 88.66 mm and of P. digitatum by 88.67 & 87.67 mm, respectively and were found to be at par with each other. Among different GRAS chemicals and botanicals evaluated against test pathogens, copper sulphate, boric acid, sodium bicarbonate and sodium carbonate at 100mM and above concentrations among chemicals and garlic extract at 10 per cent and above concentration among botanicals showed complete inhibition (100.0 percent) of both test pathogens under in vitro, whereas, under in vivo garlic extract at the concentration of 15 percent showed complete inhibition of green (100.0 percent) and of blue mold rot (92.22 percent). Boric acid at the concentration of 4 percent showed complete inhibition (100.0 percent) of both the test pathogens.
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    Molecular mapping of resistance gene(s) for cereal cyst nematode in bread wheat (Triticum aestivum L.)
    (Punjab Agricultural University, Ludhiana, 2021) Ashish; Koulagi, Ramanna
    Wheat is one of the most important human food grains and it’s a staple food of the maximum population of the world. Heterodera avenae causing Molya disease in northern and northwestern plain zones is responsible for an annual loss of 8967.52 million rupees per year in India. To overcome this resistant breeding is the most economical and eco-friendly approach. The introgression lines were derived in background of PBW343 by crossing AUS15895. Phenotypic data was recorded for two consecutive cropping seasons (2019-20 and 2020-21). The phenotypic results revealed from both cropping seasons (2019-20 and 2020-21) that among 116 introgression lines 68 were found resistant and 10 were moderately resistant, 14 were moderately susceptible and 24 were susceptible. Upon calculation of chi square test, the BC1F6 population followed resistant 1:1 susceptible segregation ratio. Six SSR (Xwmc382, Cre5, Cre8, Cre1, CreX and Cre3) markers were employed in this study to survey the polymorphism in parents. Among the six, four markers (Xwmc382, Cre5, Cre8 and Cre1) showed the polymorphism on parents as well as on introgression lines. The marker Xwmc382 is tightly linked to resistance with highest correlation coefficient (0.1). Markers efficacy was calculated to know the efficacy rate of the markers, these results followed the same trend of marker correlation coefficient Xwmc382 is more efficient to determine the resistance against Ludhiana population of cereal cyst nematode, Heterodera avenae with 66% efficacy.
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    Detection and transmission of phytoplasma/virus(es) infecting brinjal (Solanum melongena L.) in Punjab
    (Punjab Agricultural University, Ludhiana, 2021) Sen, Bheem; Sharma, Abhishek
    Phytoplasma/virus disease complex is a major obstruction against brinjal production. In present study, survey conducted in major brinjal growing areas of Punjab and observed that phytoplasma/virus disease complex was present in all surveyed areas having disease incidence ranging from 8-21 per cent causing different type of symptoms viz. yellow mosaic, mottling, wavy margin, puckering, leafroll, little leaf, giant calyx, big bud, phyllody, virescence, stunting and withes’ broom. Under Punjab conditons association of five RNA viruses viz. PepMoV, PLRV, PVX, PVYn, PVYo/c, ssDNA virus (Begomovirus) and phytoplasma (Aster yellows phytoplasma) were revealed with this disease complex. The begomoviruses associated with this disease complex were identified as Tomato leaf curl New Delhi virus and Tomato leaf curl Palampur virus. Under transmission studies whitefly was confirmed as the vector of begomoviruses. Histopathological studies of leaf lamella (showing little leaf), flower petal (showing phyllody) and giant calyx divulged many ultrastructural changes in dermal, ground and vascular tissues. In search of host plant resistance 135 cultivated genotypes and six wild relative species of brinjal were screened against phytoplasma/virus disease complex, under open field conditions. Out of these 24 cultivated genotypes and three wild species were screened against begomovirus, under artificial screening conditions. Screening results revealed that brinjal genotype P-67 and two wild species viz. Solanum sisymbrifolium and S. torvum were showing resistance against begomovirus however, in PCR assay using PALIc1960/PARIv722 primers all 24 genotypes were showing positive reaction for presence of begomovirus. But S. sisymbrifolium and S. torvum were showing negative reaction in PCR.