Plant Virus Transmission: Modes and Vectors

Abstract

Viruses are tiny, obligate intracellular parasites that, by definition, carry either an RNA or DNA genome enclosed within a protective protein shell encoded by the virus itself. Plant viruses are obligate intracellular parasites that depend on various transmission methods, presenting major challenges to global agriculture and food security. The study aims to examine the modes and vectors of plant virus transmission. They cause over $30 billion in crop losses annually and are responsible for nearly half of all emerging plant diseases (Hilaire et al., 2022). Transmission involves spreading viruses from infected to healthy hosts (Gresikova, 2022), with approximately 1,600 plant viruses transmitted through various mechanisms (Peter, 2024). Transmission occurs via horizontal and vertical modes. Horizontal transmission includes mechanical means, vegetative propagation, and vectors. Examples include Tobacco Mosaic Virus (mechanical sap transmission) and Citrus Tristeza Virus (vegetative propagation). Vector-mediated transmission, the most significant pathway, involves fungi, nematodes, and insects, with over 75% of known phytoviruses transmitted through insect carriers such as aphids, whiteflies, and leafhoppers (Bragard et al., 2013). These relationships are divided into three classes according to transmission duration: non-persistent, semi-persistent, and persistent exemplified by The whitefly Bemisia tabaci serves as a vector for Tomato Yellow Leaf Curl Virus persistently, and Myzus persicae spreads Banana Bunchy Top Virus. Other vectors include dodders (Cuscuta spp.), fungi, and soil nematodes like NEPO Virus and NETU Virus (e.g., Xiphinema spp., Trichodorus spp.), which carry viruses externally or on spores. Vertical transmission, by contrast, occurs through seeds or pollen, allowing viruses to infect progeny directly. The diversity of transmission methods complicates the management of plant viral diseases. Mechanical transmission, for example, involves physical damage to plant cells. Vegetative transmission, such as through grafting or cuttings. Moreover, seed-borne and pollen-mediated transmission play crucial roles in spreading plant viruses over long distances, sometimes without obvious symptoms in the host. Understanding these pathways and vector-virus interactions is critical for developing integrated management strategies, reducing virus-induced crop losses, and supporting sustainable agricultural practices. Given the global nature of agricultural trade and the movement of plant material, it is imperative to implement comprehensive measures, including quarantine protocols, vector control, and the use of resistant plant varieties, to mitigate the impact of plant viruses and safeguard food production systems worldwide.