SUMMARY The yellow mosaic diseases of a number of legumes across Southern Asia are caused by four species of whitefly‐transmitted geminiviruses (genus Begomovirus, family Geminiviridae): Mungbean yellow mosaic virus, Mungbean yellow mosaic India virus, Dolichos yellow mosaic virus and Horsegram yellow mosaic virus. They cause losses to a number of important pulse crops, a major source of dietary protein in the region. The viruses have host ranges limited to plants of the family Fabaceae and efforts to limit losses are hampered by limited availability of conventional resistance sources and/or the lack of durability of the resistance that has been identified. There is ample evidence for genetic interaction between these begomoviruses within the legumes, in the form of both classical recombination and component exchange, but little evidence for interaction with viruses that infect other plants. This is indicative of genetic isolation, the viruses in legumes evolving independently of the begomoviruses in plant species of other families. This has implications for the development of engineered resistance in legumes, which holds the promise of durability but has yet to be transferred to the field. Taxonomy:   The viruses causing yellow mosaic diseases of legumes across southern Asia, four of which have been identified so far, are bipartite begomoviruses (genus Begomovirus, family Geminiviridae): Mungbean yellow mosaic virus, Mungbean yellow mosaic India virus, Horsegram yellow mosaic virus and Dolichos yellow mosaic virus. Physical properties:   The legume yellow mosaic viruses (LYMVs), like all members of the Geminiviridae, have geminate (twinned) particles, 18–20 nm in diameter, 30 nm long, apparently consisting of two incomplete T = 1 icosahedra joined together in a structure with 22 pentameric capsomers and 110 identical protein subunits. Disease symptoms:   Symptoms caused by LYMVs are largely dependent on host species and susceptibility. Initially symptoms appear as small yellow specks along the veins and then spread over the leaf. In severe infections the entire leaf may become chlorotic. In blackgram the chlorotic areas sometimes turn necrotic. Infections of French bean usually do not produce a mosaic but instead induce a downward leaf curling. Disease control:   Control is based mainly on preventing the establishment of the whitefly vector, Bemisia tabaci, in the crop by application of insecticides. Changes in agricultural practices, such as moving the cropping period out of periods of high vector incidence (the wet period in late summer) to times of low vector incidence (dry season in early summer) have met with some, albeit short‐term, benefits. The use of natural, host plant resistance is efficacious, although the available sources of resistance in most legume crops are limited. In mungbean the resistance is attributed to two recessive genes which are used effectively to control the disease. Useful websites:   http://www.danforthcentre.org/iltab/geminiviridae/, http://www.iwglvv.org/

BackgroundHepatitis B virus (HBV) infection is a serious health problem in the developing countries including Pakistan. Various risk factors are responsible for the spread of this infectious disease. Prevalence of HBV infection in apparently suspected individual of Punjab province of Pakistan was analyzed during January 2008 to December 2010. Current study was aimed to investigate the epidemiology and risk factors of HBV infection.MethodologyFour thousand eight hundred and ninety patients suffering from chronic liver disease were screened for the presence of HBV DNA using qualitative Real Time PCR methodology to confirm their status of infection. A predesigned standard questionnaire was filled for all the patients that included information about the possible risk factors.ResultsA total of 4890 ELISA positive patients were screened for Hepatitis B virus infection. Of these 3143 were positive for HBV, includes 68.15% males and 31.85% females. Male were observed to be more frequently infected as compared to the female with a positivity ratio of 2.14: 1. The rate of infection increases with the passage of time in the course of three years. Highest frequency of infection was found in the age of 21-30 was 34.93% followed by 23.83% in 31-40. Only (13.39%) were belonging to the age group 11-20 year. The rate of infection declines with increasing age as shown by age groups 41-50 (16.13%) and 51-60 (7.09%). While children aged 0-10 and very old >60 age groups were very less frequently 1.49% and 1.65% infected respectively. Important risk factors contributing to HBV spread include barber risk (23.60%), blood transfusion (4.04%), History of injection 26.19%, Reuse of syringes 26.60%, dental risk (11.20%) and surgical procedure (4.26%). Among the entire respondents trend sharing personal items was very common. History of injection, barber risk, surgery and dental procedure and reuse of syringes appear as major risk factors for the transmission.ConclusionMale were more frequently exposed to the risk factors as compared to female. Similarly the younger age group had high rate of infection as compared to the children's and the older age groups. Reuse of syringes', barber risk and History of injection were main risk identified during the present study. To lower HBV transmission rate Government should take aggressive steps towards massive awareness and vaccination programs to decrease the burden of HBV from the Punjab province of Pakistan.

Grain legumes are an important source of dietary protein across southern Asia, but they suffer extensive losses due to several viruses that are members of the genus Begomovirus (family Geminiviridae), which are collectively known as legume yellow mosaic viruses (LYMVs). Despite their economic importance, little attention has been paid to LYMVs in Pakistan and only partial sequences of virus isolates originating from this country are available in the databases. Here, a survey of LYMVs occurring across Pakistan is described. Complete sequences of 44 components (23 DNA-A, 19 DNA-B and 2 betasatellites) were determined. The results show that only the mungbean yellow mosaic India virus (MYMIV) is of agricultural significance in Pakistan having been isolated from all cultivated grain legumes examined. Mungbean yellow mosaic virus, a significant crop pathogen in India, was only identified in a weed, which together with a novel species of LYMV we reported earlier, represents the first LYMV identified in non-cultivated plants. MYMIV was shown to occur as two types in Pakistan that show phylogeographical segregation. Additionally, two begomovirus species not considered pathogens of legumes and a betasatellite were isolated. This is of grave concern since it suggests that the presumed genetic isolation of the LYMVs in legumes may be being breached. LYMVs show little, if any, evidence of interspecific recombination with non-legume infecting begomoviruses. Thus, either recombination with non-legume viruses or interaction with betasatellites, which are host range and pathogenicity determining satellites of begomoviruses, could lead to the appearance of more aggressive virus variants/strains affecting legumes.

Cassava brown streak disease (CBSD) threatens food and economic security for smallholder farmers throughout East and Central Africa, and poses a threat to cassava production in West Africa. CBSD is caused by two whitefly-transmitted virus species: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (Genus: Ipomovirus, Family Potyviridae). Although varying levels of tolerance have been achieved through conventional breeding, to date, effective resistance to CBSD within East African cassava germplasm has not been identified. RNAi technology was utilized to integrate CBSD resistance into the Ugandan farmer-preferred cassava cultivar TME 204. Transgenic plant lines were generated expressing an inverted repeat construct (p5001) derived from coat-protein (CP) sequences of CBSV and UCBSV fused in tandem. Northern blots using probes specific for each CP sequence were performed to characterize 169 independent transgenic lines for accumulation of CP-derived siRNAs. Transgenic plant lines accumulating low, medium and high levels of siRNAs were bud graft challenged with the virulent CBSV Naliendele isolate alone or in combination with UCBSV. Resistance to CBSD in the greenhouse directly correlated to levels of CP-derived siRNAs as determined by visual assessment of leaf and storage root symptoms, and RT-PCR diagnosis for presence of the pathogens. Low expressing lines were found to be susceptible to CBSV and UCBSV, while medium to high accumulating plant lines were resistant to both virus species. Absence of detectable virus in the best performing p5001 transgenic lines was further confirmed by back-inoculation via sap or graft challenge to CBSD susceptible Nicotiana benthamiana and cassava cultivar 60444, respectively. Data presented shows robust resistance of transgenic p5001 TME 204 lines to both CBSV and UCBSV under greenhouse conditions. Levels of resistance correlated directly with levels of transgene derived siRNA expression such that the latter can be used as predictor of resistance to CBSD.

SummaryStorage roots of cassava (Manihot esculenta Crantz), a major subsistence crop of sub‐Saharan Africa, are calorie rich but deficient in essential micronutrients, including provitamin A β‐carotene. In this study, β‐carotene concentrations in cassava storage roots were enhanced by co‐expression of transgenes for deoxy‐d‐xylulose‐5‐phosphate synthase (DXS) and bacterial phytoene synthase (crtB), mediated by the patatin‐type 1 promoter. Storage roots harvested from field‐grown plants accumulated carotenoids to ≤50 μg/g DW, 15‐ to 20‐fold increases relative to roots from nontransgenic plants. Approximately 85%–90% of these carotenoids accumulated as all‐trans‐β‐carotene, the most nutritionally efficacious carotenoid. β‐Carotene‐accumulating storage roots displayed delayed onset of postharvest physiological deterioration, a major constraint limiting utilization of cassava products. Large metabolite changes were detected in β‐carotene‐enhanced storage roots. Most significantly, an inverse correlation was observed between β‐carotene and dry matter content, with reductions of 50%–60% of dry matter content in the highest carotenoid‐accumulating storage roots of different cultivars. Further analysis confirmed a concomitant reduction in starch content and increased levels of total fatty acids, triacylglycerols, soluble sugars and abscisic acid. Potato engineered to co‐express DXS and crtB displayed a similar correlation between β‐carotene accumulation, reduced dry matter and starch content and elevated oil and soluble sugars in tubers. Transcriptome analyses revealed a reduced expression of genes involved in starch biosynthesis including ADP‐glucose pyrophosphorylase genes in transgenic, carotene‐accumulating cassava roots relative to nontransgenic roots. These findings highlight unintended metabolic consequences of provitamin A biofortification of starch‐rich organs and point to strategies for redirecting metabolic flux to restore starch production.