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Variability among isolates of Alternaria solani Ell. And Mart, causing Alternaria blight of tomato and induction of resistance against the disease under controlled condition

KrishiKosh

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Title Variability among isolates of Alternaria solani Ell. And Mart, causing Alternaria blight of tomato and induction of resistance against the disease under controlled condition
 
Creator Nishant Prakash
 
Contributor Vishunavat, Karuna
 
Subject variability, isolates, alternaria solani, fungal diseases, tomatoes, blight, disease resistance, germplasm, induction, uttarakhand
 
Description Thesis-PhD
Early blight is one of the devastating disease of tomato causing upto 78% yield loss. The present investigation is carried out to (i) study the variability of A.solani population in Uttarakhand, (ii) screening of tomato germplasm for field resistance and (iii) induction of resistance in tomato seedlings using resistance inducing treatments, SA (Salicylic acid), abcissic acid (ABA) and Pseudomonas fluorescens strain-2(Psf).
The symptom of early blight of tomato appears on leaves, stem and fruit. A.solani produces grayish white colonies on culture media which later turns to grayish black. The mycelium was filamentous, branched, septate and hyaline to light brown. Conidia are muriform (60-30x12-19 μm). A total of 28 isolates of A.solani,have been isolated from different agroclimatic zone of Uttarkhand. Often A.solani looses sporulation on subculturing.
Thirteen different growth media was screened to find the best media supporting sporulation and mycelial growth of A.solani. Maximum mycelial growth of 90 mm of A.solani recorded on PDA, Phytone agar and Czapeck’s Dox agar. Out of three incubation condition, viz., T1(21+10C in dark period for 14 days), T2 (One week continuous florescent light at 25+10C followed by one week period dark at 21+10C) and T3 (12 h alternate light period and dark period at 25+10C temperature), T2 incubation condition supported sporulation in all seven isolates with varying degree (profuse, moderate, poor and very poor). Pearl-millet CaCO3 media found to be best media which support sporulation in most of isolates of A.solani with varying degree under T2 incubation condition. A comparative study of radial growth of A.solani isolates was studied on three different media (PDA, V8 and Czapecck’s Dox agar). Maximum mycelial growth was recorded on PDA followed by Czapeck’s Dox agar.
Conidial morphology at 40X varies from 39.4 to 76.5 μm in length and 8.16-27.05 μm in width. Isolate As-6
exhibited maximum sporulation while As-2 minimal. A.solani isolates produces circular colony on PDA while irregular colony on Czapeck’s Dox agar medium. Most of the isolates produces irregular colon y on V8 except As- 2, As-11 and As-19.On inoculation of A.solani isolates on Arka Vikas, isolate As-2 showed shortest (5 days) incubation period while isolate As-24 with the longest (15 days) mean incubation period. As-2 rated as highly virulent (PDI 78.26%) while As-1 as least virulent (PDI 38.64%). Genetic variability was studied using SSR markers. Isolate As-2 and As-7 was found highly diverse from rest of the A.solani isolates. Twenty three tomato lines/cultivar were screened against two diverse A.solani isolates As-2 and As-9. None of the entry showed complete resistance against Early blight isolate As2 and As-9. Lines C-12, C13 and C-23 gave moderately resistant reaction against both the isolates As-2 and As-9.
Screening of tomato under cultivars under field condition was performed in the year 2011-12 and 2012-13. Entry C-1, C-6, C-11 to C-13and C-23 showed moderately susceptible reaction while C-2 to C-5, C-8 to C-10, C-16, C-17, C-20 and C-21 showed susceptible reaction and C-7, C-14, C-15 and C-22 showed high susceptible reaction against early blight diease.
30days old seedlings was treated with resisstance inducing treatments, Salicylic acid (SA), abcissic acid (ABA) and P.fluorescens strain-2 (Psf), against early blight of tomato. All the three treatment showed significant reduction in Per cent disease index under glasshouse condition. On biochemical analysis, significant increase in PAL (Phenyl Ammonia Lyase), PPO (Polyphenol oxidase), POD (Peroxidase) and total phenol content was recorded in SA, ABA and Psf treatment as compared to check. The expressionof defense gene viz., PR-1 and GLU was upregulated in SA and ABA treatment as compared to check while no expression of PR-1 and GLU gene was recorded in case of Psf confirming that Psf could not induce PR protein genes. Hence it can be concluded that SA, ABA and Psf can play significant role in reduction of early blight disease.
 
Date 2016-06-10T11:21:21Z
2016-06-10T11:21:21Z
2014-06
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67155
 
Language en_US
 
Format application/pdf
 
Publisher G.B. Pant University of Agriculture & Technology, Pantnagar - 263145 (Uttarakhand)