Gemini Viruses-emerging threat to crops

Abstract

Geminiviruses represent a new threat to global food security and sustainability by causing heavy losses on food, feed and cash crops. During the last two decades, epidemics of re-emerging and newly emerging geminiviruses have caused huge crop losses and threatened crop production, particularly in the tropics and subtropics region. Geminiviruses (family Geminiviridae) are a large group of plant viruses that possess small circular single-stranded (ss)DNA genomes that are encapsidated in twinned virions. Geminiviridae is second largest family of plant viruses. Begomoviruses have emerged as major problems in crops like cassava, cotton, grain legumes and vegetables. These geminiviruses cause economically important diseases of food, feed and fiber crops worldwide and the extent of yield loss caused by geminiviruses can reach up to 100 per cent. Epidemics caused by re‐emerging and newly emerging geminiviruses are becoming frequent even in regions that were earlier free from these viruses. Major contributory factors for the emergence and spread of new geminivirus diseases are the evolution of variants of the viruses, appearance of the whitefly ‘B’ biotype and the increase in the vector population. Management of geminiviruses is a worldwide challenge because of the widespread distribution of economically important diseases. Application of insecticide to manage vectors is the most widely used measure but can cause undesirable effect on environmental and human health. Management is most effective with an integrated pest management (IPM) approach.