“MOLECULAR CHARACTERIZATION OF TOMATO (Solanum esculentum) GENOTYPES FOR LEAF CURL VIRUSES (ToLCV)”. 2342
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2017-06
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Abstract
Key words: Tomato, Genetic diversity, Disease severity scoring, Molecular markers.
Tomato is one of the most widely grown vegetable crops and popular due to its high nutritive value, taste and versatile use. Tomato leaf curl is one of the most devastating viral diseases of cultivated tomato in tropical and subtropical regions worldwide, and losses of up to 100% are frequent. Molecular screening are essential for future breeding programmers to find out a resistance varieties against diseases.
The present investigation on “Molecular characterization of tomato (Solanum esculentum) genotypes for leaf curl viruses (ToLCV)” was conducted at Department of Biotechnology, Junagadh Agricultural University, Junagadh during October 2016 to February 2017 with objectives, to study the genetic diversity of different tomato cultivars against leaf curl virus using PCR based molecular markers, to find out the phylogenic relationship among different tomato genotypes and to screen resistant and susceptible tomato cultivars against leaf curl virus using resistance gene specific marker. The research work consists total 22 cultivars, 20 primers in each molecular markers viz, RAPD, ISSR, SSR and also 6 gene specific primers are used. Disease scoring was done for three replications in natural conditions.
From the total 22 varieties the variety Arka rakshak selected as resistant variety were remain free from leaf curl virus infection in natural condition. The highest disease percentage (91.7) was observed in case of genotype JTL-15-71 which remains statistically at par with local susceptible check variety JT-3(86.7%) which was followed by genotype JTL-15-05 (83.3%). Arka vikas variety showed 73.3% disease sevearity in present experiment.
Abstract
Total 20 RAPD primer were amplified 231 bands where polymorphic bands were 206 with the average value 10.3 per primer includes 179 total shared polymorphic bands and 27 unique bands. PIC value ranges from 0.70 to 0.93 with an average value 0.8665. 20 ISSR primers yields 221 bands with 200 polymorphic bands produced average value 10 per primer. It embrace 171 shared and 19 unique patterns. PIC value ranges from 0.6880 to 0.9338 with average value 0.65651 and 20 SSR primers yields 41 bands, contains 25 polymorphic bands with the average value 1.13 per primer includes 17 and 8 total shared and unique patterns respectively. PIC value ranges from 0 to 0.7466 with an average value 0.255655.
Jaccard’s similarity coefficient from RAPD marker revealed that the lowest similarity (29%) was recorded between NTL-12-01 and Punjab chhuhara. Both the varieties showed wide and statistically variation in case of ToLCV infection in the present study also. The highest Genetic similarity (85%) was noticed between GT-1 and JTL-15-71.Jaccard’s similarity coefficient of ISSR marker revealed that the lowest similarity occur between JTL-12-11 and Punjab chhuhara (27%). The highest (90%) similarity was noticed between Bhagya and H-24. Similarity coefficient of SSR revealed that the lowest similarity occur between JTL-15-05 and ATL-11-05 (61%), while highest similarity (95%) was noticed between NTL-12-06 and NTL-12-07 varieties. The result revealed from gene specific marker that the common bands were obtained in PCR products and products after restriction digestion indicated the presence of resistance gene in all the variety screened. However the incidence of variable ToLCV infestation in all the variety suggested that the infection was governed by the genes other than the resistance genes governing susceptibility of the plants.
Therefore from the present investigation, we can conclude the data generated might be useful to some extent for the identification of the genetic diversity of different tomato cultivars against leaf curl virus, to screen resistant and susceptible tomato cultivars against leaf curl virus and also helpful for the evolutionary analysis from phylogenic relationship among different tomato genotypes which are essential for collection, conservation and its utilization in future breeding programmers.
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BIOTECHNOLOGY