Genomic, Morphological and Biological Traits of the Viruses Infecting Major Fruit Trees

Abstract

Banana trees, citrus fruit trees, pome fruit trees, grapevines, mango trees, and stone fruit trees are major fruit trees cultured worldwide and correspond to nearly 90% of the global production of woody fruit trees. In light of the above, the present manuscript summarizes the viruses that infect the major fruit trees, including their taxonomy and morphology, and highlights selected viruses that significantly affect fruit production, including their genomic and biological features. The results showed that a total of 163 viruses, belonging to 45 genera classified into 23 families have been reported to infect the major woody fruit trees. It is clear that there is higher accumulation of viruses in grapevine (80/163) compared to the other fruit trees (each corresponding to less than 35/163), while only one virus species has been reported infecting mango. Most of the viruses (over 70%) infecting woody fruit trees are positive-sense single-stranded RNA (+ssRNA), and the remainder belong to the -ssRNA, ssRNA-RT, dsRNA, ssDNA and dsDNA-RT groups (each corresponding to less than 8%). Most of the viruses are icosahedral or isometric (79/163), and their diameter ranges from 16 to 80 nm with the majority being 25–30 nm. Cross-infection has occurred in a high frequency among pome and stone fruit trees, whereas no or little cross-infection has occurred among banana, citrus and grapevine. The viruses infecting woody fruit trees are mostly transmitted by vegetative propagation, grafting, and root grafting in orchards and are usually vectored by mealybug, soft scale, aphids, mites or thrips. These viruses cause adverse effects in their fruit tree hosts, inducing a wide range of symptoms and significant damage, such as reduced yield, quality, vigor and longevity.

Variability of some isolates of Prunus necrotic ringspot virus and Prune dwarf virus infecting sour and sweet cherry in Ukraine

“…According to the preliminary data, prevalence of these viruses in mother plant orchard of cherries in Ukraine is 11.8 % for PNRSV and 8.7 % for PDV (Pavliuk et al, 2018). Both viruses belong to Ilarvirus genus, Bromoviridae family (Pallas et al, 2012). In fruit trees, infection by these viruses leads to a variety of symptoms, the manifestation of which depends on climatic conditions and the type of host plant (Kamenova et al, 2019).…”

“…In addition to transmission by grafting and other agronomic measures, spreading by pollen is a typical way of transmission (Çağlayan et al, 2011;Pallas et al, 2012). Due to their ability to transmit by pollen, PDV and PNRSV can spread rapidly in stone crop orchards and cause significant economic damage (Amari et al, 2007;Çağlayan et al, 2011;Kamenova et al, 2019;Nemeth, 1986;Umer et al, 2019).…”

Is There a “Biological Desert” With the Discovery of New Plant Viruses? A Retrospective Analysis for New Fruit Tree Viruses

“…For example, the plum pox virus (PPV, genus Potyvirus) causes "sharka" disease, the most devastating viral disease of stone fruit trees worldwide, which causes severe damages, estimating a total cost at 10 billion Euros worldwide in 30 years (García et al, 2014;Rimbaud et al, 2015). Citrus tristeza virus (CTV; genus Closterovirus) is probably the most economically important virus infecting citrus, causing a decline of sour orange rootstock, yellow seedling of lemon and grapefruit, and stem pitting in grapefruit and sweet orange (Moreno et al, 2008;Umer et al, 2019). The disease has led to the death of millions of citrus trees all over the world and has rendered millions of others useless for production (Lee, 2015).…”

High-Throughput Sequencing Application in the Diagnosis and Discovery of Plant-Infecting Viruses in Africa, A Decade Later

“…This discovery, which also marked the start of the discipline of plant virology, was made from various studies that pinpointed tobacco mosaic virus as the causal agent of a mosaic disease on tobacco plants [ 1 ]. Thenceforth, viruses have been identified in most plants including vegetables [ 2 , 3 ], legumes [ 4 , 5 ], cereals [ 6 , 7 ], fruit crops [ 8 ], ornamentals [ 9 ] and wild species [ 10 ] and constitute approximately one-third of plant disease-causing agents. Plant virus particles, frequently referred to as virions, vary in shapes and sizes.…”