Zafar Iqbal

Management of plant viruses can succeed with a stacked, diversified resistance strategy. This chapter combines non-transgenic and engineered techniques into a useful, field-based paradigm. We begin by examining non-transgenic approaches that distribute selection pressure across several loci, and induce resistance (SAR/ISR), emphasizing how these layers influence infection, titer, and epidemic progression within the confines of actual cropping conditions. Next, we look at transgenic and genome-engineering methods, such as post-transcriptional gene silencing (RNAi/PTGS) and transcriptional gene silencing (TGS/RdDM) for DNA viruses. These methods include design rules for multiplex targeting and promoter methylation to make it harder for viruses to escape; CRISPR pathways that either edit host susceptibility factors or damages directly the viral genome; and protein-mediated options (coat-protein/replicase constructs, plantibodies, and new receptor engineering). We combine host features that make it harder for vectors to spread – with selective management of insect and behavioral interference on particular landscape. Recent developments in the host were reviewed including multilayer stacking and SIGS with details of carriers for stability enhancement. We stress stewardship, risk of resistance erosion, region-specific adoption paths for smallholder and commercial systems, and outcome indicators (incidence, viral load, yield) throughout. When taken as a whole, the chapter offers decision-making resources and cutting-edge examples for creating reliable, escape-resistant programs that convert lab advancements into solid field performance.

Bemisia tabaci is a globally destructive agricultural pest and an efficient vector of begomoviruses, which cause recurrent epidemics across South Asia, including cotton leaf curl disease in Pakistan. Increasing evidence shows that bacterial endosymbionts play a central role in shaping whitefly biology, population dynamics, and vector competence. However, the distribution of these symbionts remains poorly resolved in Pakistan, a region where begomoviruses are persistent and widespread. This study investigated the cryptic species diversity, secondary endosymbiont composition and their infection frequency in B. tabaci populations collected from major agricultural regions of Pakistan. A total of 274 adult whiteflies belonging to Asia II-1 (n = 199), MEAM-1 (n = 67), Asia I (n = 7), and Asia II-8 (n = 1) were screened using a symbiont-specific PCR assay for six endosymbionts. The primary endosymbiont Candidatus Portiera aleyrodidarum was detected in all individuals, whereas five secondary endosymbionts (Arsenophonus, Cardinium, Hamiltonella, Wolbachia and Rickettsia) were identified with distinct cryptic species- and region-specific patterns. Notably, Arsenophonus was the most prevalent endosymbiont, occurring in 68% of Asia II-1, 100% of Asia I, and 21% of MEAM-1 individuals, with the highest regional prevalence in Punjab (80%) and Khyber Pakhtunkhwa (77%). Logistic regression analyses confirmed significantly higher infection probabilities in indigenous Asia II-1 populations. Network analysis revealed structured co-occurrence patterns, including strong negative associations between Arsenophonus and Hamiltonella. Phylogenetic analyses revealed close relatedness of Pakistani Arsenophonus strains to those reported from neighboring regions, indicating regional community rather than unique local diversification. The dominance of Arsenophonus in Pakistani whitefly populations is of particular significance, given its role in protecting begomoviruses within the insect vector and its implication in facilitating virus persistence and transmission. This study, for the first time in Pakistan, provides a comprehensive assessment of endosymbiont–cryptic species associations in Pakistani B. tabaci populations and highlights the dominant prevalence of Arsenophonus as a potential key player in local virus vector dynamics.

The use of nanotechnology-based delivery systems along with growth regulators of plants is a promising approach to increase the quality of fruits postharvest. This experiment was aimed at determining the impact of sonicated nanoemulsions containing methyl jasmonate (MeJA) and 1-naphthaleneacetic acid (NAA) on the quality of postharvest Tango mandarin. The findings showed the samples treated improved fruit weight, diameter, firmness and juice percentage significantly compared to the control sample. TMJ4 (10.0 µM L⁻¹) was the most effective treatment at preserving the fruit firmness, whereas TMJ3 (7.5 µM L⁻¹) was the best treatment at improving the internal quality characteristics, such as total soluble solids, sugar–acid ratio, phenolics, flavonoids, flavonols, and antioxidant activity. Reduction in titratable acidity and a subsequent increase in sugar-to-acid ratio indicated a better maturation behavior and flavor profile of the fruit. The augmented retention of bioactive compounds implies the stimulation of secondary metabolite pathways and stress tolerance. The results suggest that nanoemulsion delivery of methyl jasmonate and NAA by sonication is an efficient method of enhancing the quality of the postharvest and prolonging the shelf life of Tango mandarin.

Plant viruses pose a persistent and escalating threat to global agriculture and food security, inflicting over $30 billion in annual losses – a challenge acutely felt in Saudi Arabia as it strives for agricultural self-sufficiency under Vision 2030. This is the first comprehensive review which presents seven decades of plant virology research in the Kingdom, from early symptom-based diagnosis to advanced molecular, genomic, and bioinformatics advances. A total of ~81 plant viral species infecting 46 plant host species have been documented across the major agroecological regions, dominated by positive-sense single-stranded RNA viruses (~70%). Among these viruses, some are economically most destructive—including alfalfa mosaic virus, cucumber mosaic virus, soilborne cereal mosaic virus, tomato yellow leaf curl virus, zucchini yellow mosaic virus, watermelon chlorotic stunt virus, and barley mild mosaic virus—posing recurrent challenges to key crops such as alfalfa, cucurbits, and tomatoes. Network analysis of virus distribution revealed strong epidemiological linkages among central and western agricultural regions, possibly driven by intensive cultivation and vector ecology. The review highlights emerging management strategies including CRISPR–Cas diagnostics, RNA interference, AI-based detection, nanotechnology, and plant growth promoting rhizobacteria. Gaps persist in genomic surveillance, vector ecology, and biosecurity enforcement. The review concludes with future research priorities emphasizing innovation, interdisciplinary collaboration, and the development of a national plant virus genomic and surveillance framework to secure sustainable agriculture in line with Vision 2030.

Antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) have emerged as critical environmental contaminants posing serious ecological and public health concerns. The widespread occurrence and proliferation of ARB and ARGs in wastewater treatment plants (WWTPs) and reclaimed wastewater (RWW) used for irrigation represent major pathways for their dissemination into the environment. Current knowledge indicates that ARGs from the environmental resistome can be transferred among diverse microbial communities, including clinically relevant human pathogens. Numerous studies have also linked the expansion of the environmental resistome to anthropogenic activities. Therefore, preventing and mitigating the spread of antibiotic resistance in the environment requires a deeper understanding of how resistance genes evolve, transfer, and persist across ecological compartments. This review synthesizes the current state of knowledge on the occurrence, prevalence, and detection of antibiotics, ARB, and ARGs in various environmental matrices, providing essential insights for developing preventive strategies and promoting the sustainable management of ecosystems.

Biofuels represent a sustainable alternative to fossil fuels, with non-food feedstock offering particular promise. This study evaluated Pongamia pinnata seeds as a dual feedstock for biodiesel and bioethanol production. Moisture content was determined at 8.0%, favorably lower than most lignocellulosic biomasses. FTIR analysis confirmed the presence of cellulose, hemicellulose, and lignin, indicating its suitability for biofuel production. Biodiesel was produced via alkaline transesterification, with the highest conversion (70%) obtained at a 5:1 alcohol-to-oil ratio. The de-oiled seed cake, rich in carbohydrates and low in lignin, was optimized for glucose release through Response Surface Methodology. Optimal conditions (100°C, 2.5 g substrate, 1.75% H ₂ SO ₄ , 60 min) yielded 429 mg g ⁻¹ glucose. Enzymatic hydrolysis further enhanced sugar release, with maximum glucose (118.21 mg g ⁻¹ ) achieved at 72 h with a 2.0 mL enzyme load. Subsequent fermentation with Saccharomyces cerevisiae produced 6.71% ethanol. These findings highlight the potential of P. pinnata as a feedstock for integrated biorefineries, supporting sustainable biofuel production.

Watermelon chlorotic stunt virus (WmCSV), a bipartite begomovirus, poses a severe and expanding threat to global cucurbit and watermelon production, driving an urgent need to unravel its genetic diversity indices and evolutionary complexities. To elucidate its evolutionary history, this study investigated the genetic diversity, evolutionary dynamics, and global dispersal of its genomic components, DNA-A (WmA) and DNA-B (WmB). The analyses uncovered striking contrasts between the components. WmB exhibited markedly greater genetic diversity (π = 0.0508 vs. 0.0119 for WmA), a slightly faster evolutionary rate (1.26 × 10⁻⁴ vs. 1.44 × 10⁻³ substitutions/site/year), and a far more complex recombination profile, with 34 events detected compared to only one in WmA. The abundance of recombination breakpoints in WmB underscores its central role in shaping genomic variability and adaptive potential. Phylogenetic analyses of both components unveil eight robustly supported clades per segment, predominantly shaped by geographical boundaries, hinting at localized evolutionary trajectories with constrained long-distance gene flow, with the exception of Oman. Bayesian time-scaled phylogenies and phylogeographic reconstructions further illuminate distinct dissemination pathways, suggesting an intriguing origin, with WmA likely emerging from the United States and WmB tracing back to Saudi Arabia, while the Middle East emerges as a dynamic epicenter for regional spread and subsequent incursions into the Americas. Together, these findings reveal contrasting evolutionary forces driving WmCSV diversification and provide critical insights into its origins and ongoing global emergence.

The application of organic manure/substances in soil can directly alter soil structure and influence the soil organic carbon (SOC), soil aggregate stability, and aggregate-associated nitrogen (N).

Date Fruit Unripening Syndrome (DFUS), a very recently observed phenomenon, is a devastating non-ripening disorder hindering the Rutab-to-Tamar transition. While observed sporadically since 2019, DFUS became prominent in 2024, disproportionately affecting the economically important Khalas cultivar (40%), followed by Sheshi (19%), Reziz and Ghur (16%), and Shahal (10%) in Al-Ahsa. With the highest incidence in Al-Ahsa (20-30%), followed by Riyadh (10-15%) and Al-Qassim (5-10%), DFUS significantly reduces fruit quality and yield, threatening farmers’ livelihoods and the socio-economic stability of date palm-dependent communities. This pioneering study investigated the impact of environmental factors—temperature, relative humidity, solar UV index, heat units, and irradiance—on date palm fruit ripening in Al-Ahsa, Saudi Arabia, from 2019 to 2024, employing ANOVA (p ≤ 0.05) and Duncan’s Multiple Range Test for robust statistical analysis. Significant inter-annual temperature variations, including daytime extremes up to 48 °C during Kimri and Khalal stages, potentially disrupted fruit metabolism and ripening. Relative humidity (RH) ranged widely (5-96%), with the Khalal stage particularly sensitive to low humidity, while high RH during the Rutab stage (2023/2024) may have hindered the necessary moisture loss thus negatively impacting the fruit ripening. Increased solar UV exposure, particularly during the Khalal and Rutab stages, may have contributed to DFUS by disrupting fruit pigment synthesis and inducing oxidative stress. Total heat unit accumulation peaked in 2024, while total irradiance declined, potentially hindering sugar conversion and softening during Rutab. Through meticulous field observations and environmental data analysis, we identified critical stressors—such as temperature fluctuations, elevated heat units, and high solar UV indices—as key drivers of DFUS. These findings provide crucial insights into the mechanisms behind DFUS, enabling the development of targeted interventions, such as optimized agricultural practices and potentially genetic solutions, to mitigate the syndrome and protect palm productivity.