Emerging evidence of seed transmission of begomoviruses: implications in global circulation and disease outbreak

Virus-Induced Genome Editing (VIGE): One Step Away from an Agricultural Revolution

There is currently a worldwide trend towards deregulating the use of genome-edited plants. Virus-induced genome editing (VIGE) is a novel technique that utilizes viral vectors to transiently deliver clustered regularly interspaced short palindromic repeat (CRISPR) components into plant cells. It potentially allows us to obtain transgene-free events in any plant species in a single generation without in vitro tissue culture. This technology has great potential for agriculture and is already being applied to more than 14 plant species using more than 20 viruses. The main limitations of VIGE include insufficient vector capacity, unstable expression of CRISPR-associated (Cas) protein, plant immune reaction, host specificity, and reduced viral activity in meristem. Various solutions to these problems have been proposed, such as fusion of mobile elements, RNAi suppressors, novel miniature Cas proteins, and seed-borne viruses, but the final goal has not yet been achieved. In this review, the mechanism underlying the ability of different classes of plant viruses to transiently edit genomes is explained. It not only focuses on the latest achievements in virus-induced editing of crops but also provides suggestions for improving the technology. This review may serve as a source of new ideas for those planning to develop new approaches in VIGE.

Variable infection mechanisms of mungbean yellow mosaic India virus in diverse Vigna species: New insights from differential gene expression

The extent of viral infection significantly shapes disease susceptibility. Yellow mosaic disease induced by the begomovirus pathogen mungbean yellow mosaic India virus (MYMIV), revealed varying infection levels in both compatible and incompatible interactions across three distinct Vigna species such black gram, green gram, and rice bean. Differential gene expression analysis focused on MYMIV coat protein (AV1) and replication protein (AC1) highlighted elevated AV1 expression in the susceptible green gram genotype SML1082 compared to the black gram genotype KUG253. Conversely, AC1 showed higher expression in black gram than green gram, illustrating complex infection mechanisms among compatible MYMIV-Vigna interactions. A novel infection pathway, termed "Lack of Efficient Assembly (LEA)," has been hypothesized in MYMIV-Vigna interactions. Additionally, a whitefly-mediated artificial transmission model for begomoviruses, named Transparent Airflow Stress-free Container (TASC), has been designed and demonstrated for the efficient transmission of MYMIV. This study enhances the understanding of begomovirus infection dynamics in diverse Vigna species, offering insights into disease management strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01547-9.

Cucurbit Leaf Crumple Virus Is Seed Transmitted in Yellow Squash (Cucurbita pepo)

The traditional understanding of begomovirus transmission exclusively through the whitefly Bemisia tabaci (Gennadius) has shifted with findings of seed transmission in some begomoviruses over the last decade. We investigated the seed transmissibility of cucurbit leaf crumple virus (CuLCrV), a bipartite begomovirus that has recently emerged as a severe constraint for yellow squash (Cucurbita pepo L.) production in the southeastern United States. We found a high concentration of CuLCrV in the male and female flower tissues of infected squash, including the pollen and ovules. The virus infiltrated the fruit tissues, including the endocarp and funiculus, which are anatomically positioned adjacent to the seeds. In seeds, CuLCrV was detected in the endosperm and embryo, where there are no vascular connections, in addition to the seed coat. The virus was detected in the radicle, plumule, cotyledonary leaves, and true leaves of seedlings grown from seeds collected from infected fruits. In the grow-out test conducted, CuLCrV infections ranged from 17 to 56% of the progeny plants. To ensure that partial viral genome fragments were not being mistaken for replicative forms of the virus, we performed rolling circle amplification PCR and amplified complete DNA-A and DNA-B of CuLCrV from seed tissues, seedlings, and progeny plants of CuLCrV-infected squash. Near-complete DNA-A and DNA-B sequences of CuLCrV were recovered from a progeny plant, further validating our findings. Our results demonstrate that CuLCrV can translocate from vegetative to reproductive tissues of yellow squash, persist within the seeds, and subsequently induce infection in progeny plants, confirming its capacity for seed transmission.

An improved DNA extraction method in okra for rapid PCR detection of Okra enation leaf curl virus from diverse Indian regions

The extraction of DNA from okra (Abelmoschus esculentus) is challenging due to its high mucilage and polysaccharide content, which can hinder both the yield and quality of DNA. In this study, an improved DNA isolation method is described incorporating a key modification being the use of solution I (1 M NaCl and 2% Sarcosyl) as a pre-treatment before applying the CTAB buffer, resulting in high-purity genomic DNA in just 1 h and 45 min., making it suitable for handling large sample sizes due to its rapid processing capabilities. This enhanced DNA extraction method was crucial for the accurate and rapid molecular detection of Okra enation leaf curl virus (OELCuV), a monopartite begomovirus that has spread across various regions of India. Transmitted by the whitefly (Bemisia tabaci), OELCuV causes leaf curling, enations, and stunted growth in okra, leading to significant yield losses. The surveys conducted during the 2020-21 and 2021-22 sowing seasons revealed disease incidence ranging from 14.03 to 67.57%. The extracted DNA via the improved DNA extraction method enhanced the speed of PCR based molecular identification of OELCuV, using virus-specific coat protein primers. The amplified CP genes were cloned and sequenced to study the CP gene based diversity among OELCuV isolates from different states of India. The CP gene nucleotide identity among the studied OELCuV isolates ranged from 95.57 to 99.27%, while comparison with previously reported Indian OELCuV CP sequences, the nucleotide identity ranged from 89.35 to 98.83%. The successful application of this optimized DNA extraction method sped up the detection process but also holds promise for broader use in the molecular study of okra and other mucilaginous crops, particularly in the rapid and reliable identification of begomoviruses. The optimized DNA extraction method significantly accelerated the detection of OELCuV, demonstrating its efficiency and reliability. This method shows strong potential for broader applications in the molecular study of okra and other mucilaginous crops, making it a valuable tool for future research and disease management.