Title : Uncovering the diversity of viruses infecting leafy vegetables in South Africa, and their impact on the fresh and dry weight of the leaves
Abstract:
Smallholder and emerging farmers of South Africa depend on leafy vegetables such as Swiss chard, Brassica species (mustard spinach and rape), beet greens and Amaranth for household consumption and income generation. Viruses belonging to the Luteoviridae, Potyviridae, etc. were reported to infect these vegetables in other countries. The study aimed at identifying and genetically characterizing viruses affecting leafy vegetable production in the Gauteng Province of South Africa and to determine their impact on fresh and dry weight of Swiss chards and mustard spinach. Samples were collected in Gauteng Province (City of Tshwane, Randfontein and Germiston) using a W-pattern method of sampling, and symptomatic and non-symptomatic samples were collected. Samples were analysed using reverse transcription polymerase chain reaction (RT-PCR), cloning and sequencing part of the genomes and the use of High throughput sequencing to generate complete genome sequences of viruses detected. A preliminary trial was conducted to determine the effects of viruses on the leaf weight by planting glasshouse trials with Swiss chard and mustard spinach and mechanically inoculating plants with virus treatments. Symptoms induced by virus treatments post inoculation was recorded and data (fresh and dry leaf weight) was collected and statistically analysed. Molecular detection methods detected and confirmed viruses such as Turnip mosaic virus (TuMV), Beet mosaic virus (BtMV), Beet western yellows virus (BWYV), Beet chlorosis virus (BChV), etc. in samples collected. The fresh weight of the virus treated mustard spinach was affected and significant difference was observed. The fresh weight of Swiss chard was moderately affected by the virus treatments. These findings contribute to the development and implementation of control strategies, crucial for sustainable leafy vegetable production in South Africa.
