Shelf-life and microbiological safety studies of refrigerated petha sweet.

This study was conducted at Indian Institute of Vegetable Research, Varanasi (I.I.V.R.), Uttar Pradesh from 2006 to 2009 for evaluating comparative physico-chemical, microbiological and sensory attributes of crystallized and Kashi petha at refrigerated storage (4 ± 1 °C) condition up to 90 days. The petha were manufactured using 2 varieties of ash gourd developed at I.I.V.R. i.e.; Kashi Dhawal and Kashi Ujwal, selected based on different parameters suitable for petha sweet preparation. The used packaging materials for storage studies were laminated pouch, low density polyethylene, high density polyethylene. The physiochemical analysis and sensory evaluation were performed at 15 days interval upto 90 days for storage study in both Kashi Petha and crystallized petha, while microbial observation was recorded up to 90 days in crystallized petha and up to 50 days Kashi Petha. Physico-chemical analysis exhibited the continuous increase in moisture (25.79-26.80 % and 31.68-32.63 %) and titratable acidity (0.022-0.029 %) and (0.022-0.030 %) and reduction in ascorbic acid content (5.50-5.00 mg/100 g and 5.12-4.84 mg/100 g), respectively in crystallized and Kashi petha. The increasing trend in microbial population was more pronounced in Kashi petha in comparison to crystallized petha. The spoilage bacteria included Bacillus spp., Staphylococcus spp. and lactic acid bacteria while Aspergillus, Penicillium and Saccharomyces were observed among fungal contaminants. The bacteria, yeast and mold were identified on the basis of cultural, morphological and biochemical characterization with respect to storage period. On the basis of the overall findings of comparative physico-chemical, microbiological and sensory evaluation, 30 and 50 days of storage was considered as safe for the consumption of Kashi and crystallized petha, respectively under refrigerated environment (4 ± 1 °C).

The population genomics of begomoviruses: global scale population structure and gene flow.

BACKGROUND: The rapidly growing availability of diverse full genome sequences from across the world is increasing the feasibility of studying the large-scale population processes that underly observable pattern of virus diversity. In particular, characterizing the genetic structure of virus populations could potentially reveal much about how factors such as geographical distributions, host ranges and gene flow between populations combine to produce the discontinuous patterns of genetic diversity that we perceive as distinct virus species. Among the richest and most diverse full genome datasets that are available is that for the dicotyledonous plant infecting genus, Begomovirus, in the Family Geminiviridae. The begomoviruses all share the same whitefly vector, are highly recombinogenic and are distributed throughout tropical and subtropical regions where they seriously threaten the food security of the world's poorest people. RESULTS: We focus here on using a model-based population genetic approach to identify the genetically distinct sub-populations within the global begomovirus meta-population. We demonstrate the existence of at least seven major sub-populations that can further be sub-divided into as many as thirty four significantly differentiated and genetically cohesive minor sub-populations. Using the population structure framework revealed in the present study, we further explored the extent of gene flow and recombination between genetic populations. CONCLUSIONS: Although geographical barriers are apparently the most significant underlying cause of the seven major population sub-divisions, within the framework of these sub-divisions, we explore patterns of gene flow to reveal that both host range differences and genetic barriers to recombination have probably been major contributors to the minor population sub-divisions that we have identified. We believe that the global Begomovirus population structure revealed here could facilitate population genetics studies into how central parameters of population genetics namely selection, recombination, mutation, gene flow, and genetic drift shape the global begomovirus diversity.

Detection and frequency of recombination in tomato-infecting begomoviruses of South and Southeast Asia.

BACKGROUND: Tomato-infecting begomoviruses are widely distributed across the world and cause diseases of high economic impact on wide range of agriculturally important crops. Though recombination plays a pivotal role in diversification and evolution of these viruses, it is currently unknown whether there are differences in the number and quality of recombination events amongst different tomato-infecting begomovirus species. To examine this we sought to characterize the recombination events, estimate the frequency of recombination, and map recombination hotspots in tomato-infecting begomoviruses of South and Southeast Asia. RESULTS: Different methods used for recombination breakpoint analysis provided strong evidence for presence of recombination events in majority of the sequences analyzed. However, there was a clear evidence for absence or low Recombination events in viruses reported from North India. In addition, we provide evidence for non-random distribution of recombination events with the highest frequency of recombination being mapped in the portion of the N-terminal portion of Rep. CONCLUSION: The variable recombination observed in these viruses signified that all begomoviruses are not equally prone to recombination. Distribution of recombination hotspots was found to be reliant on the relatedness of the genomic region involved in the exchange. Overall the frequency of phylogenetic violations and number of recombination events decreased with increasing parental sequence diversity. These findings provide valuable new information for understanding the diversity and evolution of tomato-infecting begomoviruses in Asia.

Inheritance of gynoecism in bitter gourd (Momordica charantia L.).

The inheritance of sex expression in cucumber (Cucumis sativus) and other cucurbits is well documented; however, the genetics of female sex (gynoecism) expression in bitter gourd (Momordica charantia) has not been described. Inheritance of gynoecism in bitter gourd was studied in a 100% gynoecious line (Gy263B). The F(2) and testcross segregation data revealed that gynoecism in Gy263B is under the control of a single, recessive gene. Following the gene nomenclature of cucurbits, it is proposed that the gene symbol, gy-1, be assigned for the expression of gynoecism in bitter gourd.