Muhammad Yussouf Saleem

Occurrence of Cucumber mosaic virus Subgroup IA in tomato in Pakistan

Infection of tomato in Faisalabad, Pakistan with subgroup IA strain of Cucumber mosaic virus (CMV) is reported for the first time. The virus was detected by Rt-PCR using genus-specific single pair of primers and was transmitted by Myzus persicae in the non-persistent manner.ZusammenfassungMit der Untergruppe IA des Gurkenmosaikvirus infizierte Tomaten wurden erstmals in Pakistan nachgewiesen. Das Virus wurde mit einem einzelnen genusspezifischen Primer-paar mittels RT-PCR nachgewiesen. Die Übertragung durch Myzus persicae erfolgte nicht-persistent.

Effect of cucumber mosaic virus infection on morphology, yield and phenolic contents of tomato

Ten tomato genotypes were screened for their resistance against cucumber mosaic virus (CMV) and its vector Myzus persicae under natural infection in field, using aphids M. persicae under net-house and mechanical inoculation under greenhouse. Large differences were observed among genotypes for infection percentage (IP) and severity index (SI) among the testing methods used. All genotypes showing tolerance to CMV in the field or through aphid inoculation, however, become susceptible and highly susceptible after mechanical inoculation. All the test genotypes also showed susceptibility to the aphid M. persicae population. Plants inoculated with CMV showed substantial decrease in yield and yield-contributing parameters which varied with cultivars that probably depended upon its genetic make up. All the test genotypes exhibited 0.97–30.19% decrease in plant height, 11.47–52.65% decrease in root length, 46.56–95.56% decrease in fresh plant weight, 65.78–92.84% decrease in root fresh weight, 19.97–87.65% decrease in the dry weight of plants, 75.63–95.43% decrease in dry root weight, 69.51–95.65% reduction in the number of fruits and 89.04–99.89% decrease in yield per plants. After 15 days of inoculation, the quantitative analysis using double beam spectrophotometer showed an increase in total phenolics in CMV-inoculated plants as compared to un-inoculated plants among genotypes. Similarly the thin layer chromatography (TLC) on silica gel G indicated that the number of phenolic compounds was increased in most of the inoculated genotypes while in others they were either decreased or remained same.

EVALUATION OF TOMATO GENOTYPES FOR LATE BLIGHT RESISTANCE USING LOW TUNNEL ASSAY

Late blight (LB) caused by Phytophthora infestans is one of the major bottlenecks of low productivity of tomato worldwide including Pakistan. Transfer of resistance into elite lines is the principal way to combat this problem. However, lack of reliable methods to screen and evaluate plant resistance prior to breeding has been a limiting factor in the development of tomato varieties resistant to LB. In the present study, we screened 285 tomato genotypes of diverse genetic pool using a low tunnel assay for the first time to the best of our knowledge and confirmed that it is not an established method in use for the same purpose. Results over the multiyear (2013-2015) elucidated one resistant genotype LO6122 (Solanum arcanum) and 31 moderately resistant genotypes (one of S. arcanum and 30 of S. lycopersicum) to LB. Rest of the genotypes including mutants and differential plants having major LB resistant genes (Ph1, Ph2, Ph3 and Ph2 + Ph3) were ranged from susceptible to highly susceptible. Strong resistance conferred by LO6122 points out the presence of an alternate source of genes resistant to LB. Therefore, this line can possibly be used as a donor parent of resistance against virulent strains of P. infestans. This study also showed that low tunnel assay is practicable, efficient, simple, and cost effective in terms of space and pathogen inoculum required. It gives high output results to distinguish resistant and susceptible genotypes even when screening of large number of genotypes and breeding populations against LB is exercised.

Convolvulus arvensis, a new host for Alternaria solani causing early blight of Solanum lycopersicum in Pakistan

In March–April 2011, a severe outbreak of early blight disease caused by Alternaria solani was observed on Solanum lycopersicum (cultivated tomatoes) at the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan. A similar type of symptoms was also observed on Convolvulus arvensis (field bindweed, lehli). Based on disease symptoms, morphological characteristics and pathogenicity test, it has been confirmed that the A. solani could infect C. arvensis. To the best of our knowledge this is the first report of A. solani infecting C. arvensis in Pakistan.

Assessment of Genetic Diversity in Tinda Gourd Through Multivariate Analysis

There is insufficient information available concerning the genetics and association of yield components in Tinda gourd (Citrullus vulgaris var. fistulosus Stocks). Sixteen genotypes of Tinda gourd were used to estimate genetic variability, strength and direction of association, and direct/indirect effects of morphological traits on fresh fruit yield. Considerable genetic variability occurred among genotypes for all traits. The majority of variation was genetic in nature as indicated by similar values of genotypic and phenotypic coefficients of variation. High heritability coupled with low genetic advance for leaf area, fruit length, fruit diameter, number of vines per plant, number of fruit per plant, and fruit yield indicated nonadditive gene action. Fruit weight had additive gene action as indicated by high heritability and genetic advance. Fruit length, fruit diameter, fruit weight, and number of fruit per plant had a strong positive association; numbers of vines per plant were negatively correlated with yield at genotypic and phenotypic levels. Fruit weight had the most direct effect on yield, followed by fruit diameter and stem diameter. Four principal components (PCs) explained 81.19% of total observed variation. PC1 and PC2 were defined as variations attributed to nonadditive genes and variations due to additive genes and environment. Six genotypes were selected for use in breeding based upon cluster analysis.

Association of chili leaf curl betasatellite with tomato leaf curl disease

Leaf samples of Solanum lycopersicum exhibiting the tomato leaf curl disease (ToLCD) symptoms were collected from different genotypes. PCR amplifications confirmed the presence of Tomato leaf curl New Delhi virus (ToLCNDV) and betasatellite. Molecular analysis of betasatellite nucleotide sequences showed high level of sequence identity (99%) with chili leaf curl betasatellite (ChLCB) previously reported from chili in Pakistan. To the best of our knowledge, this is the first natural occurrence of ChLCB with ToLCD in Pakistan. Therefore, the association of ToLCNDV with ChLCB is also a component of begomovirus-betasatellite complex that may also affect other cropping systems.

Time-course analysis of the phenols in cucumber mosaic virus-resistant, -tolerant and -susceptible tomato genotypes

In this study, changes in quantity and quality of phenolic compounds were compared in cucumber mosaic virus (CMV)-inoculated and -un-inoculated plants of nine resistant, tolerant, susceptible and highly susceptible genotypes at three different time intervals. Total phenolic contents and the number of phenolic compounds were generally increased in CMV-inoculated plants. Maximum per cent increase in total phenolic contents over un-inoculated controls was observed as 77.55% in resistant genotype TMS-1, 84.17% in tolerant genotype L06238 and 82.88% in resistant genotype L02223 after 10, 20 and 30 days of inoculation, respectively. Thin layer chromatography of inoculated and un-inoculated plants indicates that in most of the tested genotypes, the number of phenolic compounds varied from cultivar to cultivar and within the same cultivar, depending upon the status of plants and growth stages. However, the trend of increase in quantity and quality of phenolic compounds in the tested units was not constant to draw a meaningful conclusion.