The Role of Satellites in the Evolution of Begomoviruses

Abstract

Begomoviruses have emerged as destructive pathogens of crops, particularly in the tropics and subtropics, causing enormous economic losses and threatening food security. Epidemics caused by begomoviruses have even spread in regions and crops that were previously free from these viruses. The most seriously affected crops include cassava; cotton; grain legumes; and cucurbitaceous, malvaceous, and solanaceous vegetables. Alphasatellites, betasatellites, and deltasatellites are associated with the diseases caused by begomoviruses, but begomovirus-betasatellite complexes have played significant roles in the evolution of begomoviruses, causing widespread epidemics in many economically important crops throughout the world. This article provides an overview of the evolution, distribution, and approaches used by betasatellites in the suppression of host plant defense responses and increasing disease severity.

Keywords: alphasatellites; betasatellites; deltasatellites; economic losses; global warming; whitefly-transmitted diseases.

Figure 1

Global spread of betasatellites based on >2400 sequences submitted to date from different countries (indicated by numbers); the countries that have submitted <10 sequences are shaded blue, those that have submitted <100 sequences are shaded brown, and those that have submitted >100 sequences are shaded red; the countries shaded red are hotspots for betasatellites, representing 87% of the total sequences submitted so far; 11% of the sequences have been submitted by the countries shaded brown; and the remaining 2% of sequences have been submitted by countries shaded blue. The numbers in circles indicate the sequences submitted by the connected countries.

Figure 2

The average annual rise in surface temperatures above the pre-industrial average (1850–1900) since mid-1960s, coincides with the increase in the number of begomovirus species from <30 in 1970 to 445 species in 2023, and the number of betasatellite species from 7 in 2000 to 120 species in 2023 (modified from Nature Briefing, 15 January 2024).